Progress in Neuro-Psychopharmacology and Biological Psychiatry

Published by Elsevier
Print ISSN: 0278-5846
1. In 33 patients with a depressive syndrome the effects of partial SD restricted to the 2 hours between 3:00 and 5:00 in the morning was compared to that of no SD (= undisturbed sleep, n = 17) and total SD (n = 16) in a balanced crossover design. 2. Partial SD had a moderate antidepressant effect which is, however, clearly inferior to that of total SD. 3. Reasons for the scarceness of the effect may be an inappropriate timing of this 2-hr SD period (which seems improbable), too short a duration of SD, or the resumption of sleep at 5 o'clock. 4. "Intermediate" SD in the form it was used here represents no therapeutic advantage as we had expected. Its moderate effects lend support to the hypothesis that sleep disturbance is a sign of (mostly insufficient) restorative or self-healing efforts of the depressive organism.
Benztropine (BZT) analogs, a family of agents with high affinity for the dopamine transporter have been postulated as potential treatments in stimulant abuse due to their ability to attenuate a wide range of effects evoked by psychomotor stimulants such as cocaine and amphetamine (AMPH). Repeating administration of drugs, including stimulants, can result in behavioural sensitization, a progressive increase in their psychomotor activating effects. We examined in mice the sensitizing effects and the neuroplasticity changes elicited by chronic AMPH exposure, and the modulation of these effects by the BZT derivative and atypical dopamine uptake inhibitor, JHW007, a candidate medication for stimulant abuse. The results indicated that JHW007 did not produce sensitized locomotor activity when given alone but prevented the sensitized motor behavior induced by chronic AMPH administration. Morphological analysis of medium spiny neurons of the nucleus accumbens revealed that JHW 007 prevented the neuroadaptations induced by chronic AMPH exposure, including increments in dendritic arborization, lengthening of dendritic processes and increases in spine density. Furthermore, data revealed that AMPH produced an increase in the density of asymmetric, possibly glutamatergic synapses in the nucleus accumbens, an effect that was also blocked by JHW007 pretreatment. The present observations demonstrate that JHW007 is able to prevent not only AMPH-induced behavioural sensitization but also the long-term structural changes induced by chronic AMPH in the nucleus accumbens. Such findings support the development and evaluation of BZT derivatives as possible leads for treatment in stimulant addiction.
1. The authors have determined the effect of TJS-010, a new prescription of oriental medicine, on the locomotor activity in rats. 2. Tetrabenazine(TBZ) decreased the spontaneous locomotion in rats, and attenuated the contents of amines and increased their metabolism in various regions in rat brain. 3. TJS-010 inhibited the locomotor suppression induced by TBZ: however, neither amine contents nor their metabolism was not altered, which suggested that TJS-010 postsynaptically modulated the transmission or transduction. 4. Imipramine also inhibited the decrease in locomotion induced by TBZ. 5. These results suggest a possibility that TJS-010 has an antidepressive effect.
Current views on the pathogenesis of psychiatric disorders focus on the interplay between genetic and environmental factors, with individual variation in vulnerability and resilience to hazards being part of the multifactorial development of illness. The aim of the study is to investigate the effect of glutamate transporter polymorphism SLC1A2-181A>C and exposure to Adverse Childhood Experiences (ACE) on hippocampal gray matter volume of patients with bipolar disorder (BD). Patients exposed to higher levels of ACE reported lower gray matter volume. The effect of SLC1A2-181A>C revealed itself only among patients exposed to lower levels of ACE, with T/T homozygotes showing the lowest, and G/G the highest, gray matter volume. The greatest difference between high and low exposure to ACE was observed in carriers of the G allele. Since the mutant G allele has been associated with a reduced transcriptional activity and expression of the transporter protein, we could hypothesize that after exposure to highest levels of ACE G/G homozigotes are more vulnerable to stress reporting the highest brain damage as a consequence of an excess of free glutamate.
Alcohol-induced psychotic disorder (AIPD), also known as alcohol hallucinosis, is a rare complication of alcohol abuse. The underlying pathophysiology is poorly understood, and the disorder needs to be differentiated from alcohol withdrawal delirium and schizophrenia. No brain-imaging studies in AIPD have been reported to date. Case reports of brain imaging in AIPD suggest possible dysfunction in the thalamus, basal ganglia, frontal lobes and cerebellum. Our aim was to prospectively compare resting brain perfusion (rCBF) in patients with AIPD, uncomplicated alcohol dependence, schizophrenia and healthy volunteers. Single photon emission computed tomography (SPECT) was utilized to compare rCBF in patients with AIPD (n=19), schizophrenia (n=16), uncomplicated alcohol dependence (n=20) and healthy volunteers (n=19). Increased rCBF was demonstrated in the right calcarine area in patients with AIPD compared to healthy volunteers, with a trend towards increased rCBF to the frontal and temporal lobes and the right pallidum. Decreased left sided rCBF to the putamen, parietal, mid-frontal and mid-temporal lobes and heterogenous flow to the cerebellum were demonstrated in patients with AIPD when compared to patients with uncomplicated alcohol dependence. The left posterior cingulate and right cerebellum showed higher and lower rCBF respectively in patients with AIPD compared to patients with schizophrenia. Our findings implicate the right occipital lobe and possibly the cerebellum in the pathogenesis of AIPD and have similarities with those previously reported in alcohol withdrawal. Reduced rCBF to the frontal lobes, thalamus and basal ganglia in AIPD as suggested in previous case reports could not be confirmed.
1) The imidazoline, moxonidine (MOX), injected icvt into the anterior lateral ventricle of NZW rabbits induced ocular hypotension (> 7.0 mmHg) that persisted for two hrs. 2) L-659, 066 injected i.v. or icvt inhibited MOX-induced ocular hypotension, significantly. 3) L-657, 743, injected icvt at 100-fold lower concentration than icvt L-659, 066, significantly inhibited MOX-induced ocular hypotension. 4) Alpha-2-adrenoceptors, located in the CNS, play a role in MOX-induced ocular hypotension, as evidenced by the ability of the relatively selective alpha-2 antagonists, L-659, 066 and L-657, 743 to inhibit icvt MOX-induced ocular hypotension.
1. The influence of 7-methoxytacrine (7-MEOTA) on the non epileptic myoclonus of the Papio papio baboon was studied in 5 animals. 2. This type of myoclonus is thought to depend on a cholinergic system dysfunction since it can be induced by atropine and blocked by physostigmine. 3. 7-MEOTA, a tacrine derivative, is believed to display a conspicuous anticholinesterase activity but, surprisingly, it here potentiated the non epileptic myoclonus occuring either spontaneously or induced by atropine. 4. In baboons not spontaneously presenting the non epileptic myoclonus, 7-MEOTA induced the myoclonus in a fashion similar to atropine; such a myoclonus was blocked by physostigmine. 5. These data indicate a possible antagonist action of tacrine on the muscarinic acetylcholine receptor. From these data, it is suggested that caution is necessary when introducing a tacrine derivative in clinical practice.
MPTP given to mice in 4 daily doses (20 mg/kg s.c.) resulted in 56-70% depletion of striatal dopamine 1 week after the last dose. Pretreatment with deprenyl or MD 240928, selective inhibitors of monoamine oxidase type B, or with amfonelic acid or nomifensine, selective inhibitors of dopamine uptake, prevented the depletion of striatal dopamine. In contrast, pretreatment with alpha-methyl-tyrosine, Ro 4-1284 or haloperidol did not prevent the depletion of striatal dopamine by MPTP. The results are compatible with the view that dopamine itself is not involved in the neurotoxic effect of MPTP but that MPP+, a metabolite of MPTP formed by MAO-B and accumulated by the dopamine uptake carrier, is responsible for the neurotoxicity.
We previously reported that C57 black mice were more sensitive than several other strains of mice to the neurotoxic actions of MPTP. We now report that a significantly higher amount of the 1-methyl-4-phenylpyridinium species, a very toxic metabolite of MPTP, was found in the brains of C57 black mice than in the brains of CF-W or CD-1 mice, two strains of mice which are less sensitive to MPTP. In addition, we also found that there were strain differences in the response of mice to the neurotoxic actions of methamphetamine with CF-W mice being more sensitive to methamphetamine than C57 black mice.
Representative autoradiograms of brain sections of monkey showing (A) 3 H-CGP39653 (an NMDA antagonist selective for NR1/NR2A assembly) total binding, along with (B) nonspecific binding with 500 mM NMDA; (C) 3 H-Ro 25-6981 (an NMDA antagonist selective for NR1/ NR2B assembly) total binding along with (D) nonspecific binding including 10 mM Ro 04-5595 in the incubation buffer and (E) in situ hybridization with 35 S-dATP-labeled oligonucleotides specific for NR1 subunit mRNA and (F) nonspecific hybridization obtained with the addition of a 100-fold excess of cold oligonucleotides.
Comparison of 3 H-L-glutamate, 3 H-AMPA, 3 H-CGP39653, 3 H-glycine and 3 H-Ro 25-6981 specific binding to glutamate receptors and NR1 subunit expression as well as glutamine, glutamate and glycine concentrations in the striatum between dyskinetic (n = 2) and nondyskinetic (n = 4) MPTP monkeys, which showed good antiparkinsonian response following treatment with pulsatile SKF-82958 or cabergoline. Values are expressed as the percentage mean ± S.E.M. of saline-treated MPTP monkeys (see Tables 1 -3 for control values). Statistical analyses were performed using an one-factor ANOVA followed by post-hoc pairwise comparisons with Scheffé's test.
Effect of chronic treatment of MPTP monkeys with the D 1 agonist SKF-82958 by injections (SKF-82958 pulsatile) or through osmotic minipumps (SKF-82958 continuous) or with injections of cabergoline as compared to saline-treated MPTP and control monkeys on 3 H-glutamate, 3 H-AMPA, 3 H-glycine, 3 H-Ro 25-6981 and 3 H-CGP39653 specific binding to glutamate receptors in the caudate and putamen
The effects of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced nigrostriatal lesion and dopaminomimetic treatment on parameters of glutamatergic activity within the basal ganglia of monkeys were studied in relation with the development of dyskinesias. Drug-naive controls, saline-treated MPTP monkeys, as well as MPTP monkeys treated with either a long-acting D2 agonist (cabergoline) or a D1 agonist (SKF-82958) given by intermittent injections or continuous infusion, were included in this study. 3H-L-glutamate, 3H-alpha-amino-3-hydroxy-5-methylisoxasole-4-propionate (AMPA), 3H-glycine, 3H-CGP39653 (an N-methyl-D-aspartate, NMDA, antagonist selective for NR1/NR2A assembly) and 3H-Ro 25-6981 (an NMDA antagonist selective for NR1/NR2B assembly), specific binding to glutamate receptors, the expression of the NR1 subunit of NMDA receptors and glutamate, glutamine and glycine concentrations were studied by autoradiography, in situ hybridization and high-performance liquid chromatography (HPLC), respectively. Pulsatile SKF-82958 and cabergoline treatment relieved parkinsonian symptoms, whereas animals continuously treated with SKF-82958 remained akinetic. Pulsatile SKF-82958 induced dyskinesias in two of the three animals tested, whereas cabergoline did not. MPTP induced no significant changes of striatal specific binding of the radioligands used, NR1 mRNA expression and amino acid concentrations. In the putamen, pulsatile SKF-82958 treatment was associated with decreased content of glycine and glutamate, whereas only glycine was decreased in cabergoline-treated monkeys. Cabergoline and continuous administration of SKF-82958 led to lower levels of NR1 mRNA in the caudate in comparison to pulsatile SKF-82958 administration. The development of dyskinesias following a D1 agonist treatment was associated with an upregulation of 3H-glutamate [+49%], 3H-AMPA [+38%], 3H-CGP39653 [+ 111%], 3H-glycine [+ 26%, nonsignificant] and 3H-Ro 25-6981 [+ 33%] specific binding in the striatum in comparison to nondyskinetic MPTP monkeys. Our data suggest that supersensitivity to glutamatergic input in the striatum might play a role in the pathogenesis of dopaminomimetic-induced dyskinesias and further support the therapeutic potential of glutamate antagonists in Parkinson's disease.
In vitro studies with rat striatal and liver mitochondria have shown that the neurotoxic compound MPTP (0.5 mM) has very little effect on mitochondrial energy transduction. With pyruvate-malate (P/M), mitochondria from striatum and liver exhibited state 3 oxygen consumption rates of 101.5 +/- 21.3 and 53.6 +/- 14.8, respectively. On the other hand, MPP+ (0.5 mM) inhibited the NAD-linked substrate (P/M) oxidation in both tissue preparations. MPP+ failed to influence oxidative phosphorylation when succinate was used as the substrate. Mitochondria from liver and striatum exhibited low levels of 45Ca uptake in the absence of Mg.ADP. This was increased by about 3-fold in the presence of Mg.ADP. MPP+ under either condition had very little effect on 45Ca uptake by these organelles.
1. The tetrahydropyridine trans-1-methyl-4-[4-dimethylaminophenylethenyl]-1,2,3,6-tetrahydropyridine (t-THP), like MPTP, can undergo monoamine oxidase (MAO)-mediated conversion to a dihydropyridinium intermediate and subsequent metabolism to a pyridinium species. t-THP is also a better substrate for MAO B than MAO A. In contrast to the metabolism of MPTP, the pyridinium ion derived from t-THP is highly fluorescent. This endows t-THP with potential as an in vivo visual probe for localizing the substrates of MPTP-like neurotoxicity. As a prelude to in vivo labeling studies, we examined the metabolism and uptake kinetics of t-THP and its metabolites in mouse striatal and cortical synaptosomes. 2. T-THP was found to induce a concentration-dependent and saturable fluorescence within striatal and cortical synaptosomes that was also MAO-dependent. Like MPP+, the fluorescent pyridinium ion t-P+, derived from t-THP, inhibited the uptake and facilitated the release of monoamines from synaptosomes in a concentration-dependent fashion. The ion did not rely on sodium-dependent membrane transporters for its concentration-dependent uptake into synaptosomes, although it may have an irreversible affinity for the dopamine transporter. 3. These data suggest that t-THP could be appropriate for use as a visual marker for microenvironments where MPTP-like compounds are taken up and converted to potentially neurotoxic pyridinium species. Such a marker could be employed to address some of the issues regarding the selectivity of MPTP-induced neurotoxicity.
The in vitro autoradiographic distribution of calcium channel antagonist binding sites for 1,4-dihydropyridine and phenylalkylamine has been investigated in rat, guinea pig and human brain. 1,4-dihydropyridine ([3H] (+) PN200-110) and phenylalkylamine ([3H] (-) D-888) binding sites are identically distributed in the brain of the three mammalian species studied. High densities of calcium antagonist binding sites are present in brain areas enriched in synaptic contacts such as the hippocampus, cortex and striatum. Low to moderate densities of sites are found in other regions such as the thalamus, hypothalamus and brain stem. These data demonstrate the existence of specific calcium antagonist binding sites in mammalian brain including man. These sites are discretely distributed with highest concentrations present in the hippocampus and cortex. Moreover, the similar distribution of binding sites for [3H] (+) PN200-110 and [3H] (-) D-188 suggests that 1,4-dihydropyridine and phenylalkylamine bind to the same receptor site complex in mammalian brain.
Retinoic acid-induced differentiation of SH-SY5Y human neuroblastoma cells results in the development of extensive neurite processes as well as changes in cell body morphology toward a neuronal phenotype. The authors have examined concurrent regulation of beta-amyloid precursor protein (APP) and inositol 1,4,5-trisphosphate receptor (insP(3)R) gene expression in SY5Y cells during neuronal differentiation. Of the multiple APP mRNA transcripts expressed in this cell line, retinoic acid treatment significantly increased the expression of APP(695) transcript while the level of total APP remained unchanged. In the same time course, neuronal differentiation decreased the expression of insP(3)R at both the mRNA and protein levels. These findings demonstrate an inverse relationship between APP and insP(3)R gene expression during neuronal differentiation of SH-SY5Y cells and suggest a possible change in intracellular calcium homeostasis.
1. Polychlorinated biphenyls (PCB) were released into the environment through improper disposal for decades, causing widespread contamination. Slow biodegradation and lipophilic properties of PCB caused its persistence and concentration through food webs. Exposure to these environmental contaminants through maternal transfer during early development has been associated with neurological and endocrinological alterations in several different organisms. 2. The present study extended a preliminary investigation which suggested low level exposure to PCB altered acetylcholine biosynthesis enzyme, choline acetyltransferase (ChAT), activity in the hippocampus and basal forebrain and caused aberrations in thyroid hormone and behavior. 3. Dietary exposure of 15-day-old animals to 1.25 ppm of Aroclor 1254 (LPCB) during gestation and lactation significantly elevated ChAT activity in both areas of the brain. Animals exposed to 12.5 ppm of Aroclor 1254 (HPCB) until 15 days of age demonstrated significant elevations of ChAT activity in the basal forebrain. Thyroxine (T4) concentrations were slightly elevated in 15-day-old LPCB animals and significantly depressed in HPCB exposed pups; triiodothyronine (T3) concentrations were not altered. 4. At 30 days both LPCB and HPCB treatment groups displayed significantly depressed ChAT activity in both areas of the brain. T3 and T4 concentrations were subnormal, although T4 was not significantly depressed in LPCB animals. 5. In the Morris water maze all animals, when tested between 25 and 29 days of age, improved their latency time to the platform over 10 spatial learning trials. However, when combined means of trials 8-10 were compared, HPCB exposed animals had significantly increased latency time to the podium compared to control and LPCB animals.
Our previous study described the synthesis of 4-amine derivatives of 10,11-dihydro-5H-dibenzo-alkylamine-cycloheptane, 4-amine (3-N,N-dimethylpropylamine)-10,11-dihydro-5H-dibenzo[a,d] cycloheptane-5-one (ADDCH1), and 1,2,3,4,8,9-hexahydro-dibenzocycloheptane[4,4a,5-ef]1,4-diazepin (ADDCH2), and the characterization of their antidepressant-like effect in the forced swimming test in mice. This study investigated the involvement of monoaminergic pathways in the antidepressant-like effect of these compounds in mice evaluated in the tail suspension test (TST), another animal model to screen antidepressant drugs. Our results show that the immobility time in the TST was significantly reduced by ADDCH1 (15 to 50 mg/kg, i.p.) or ADDCH2 (30 and 50 mg/kg, i.p.). The antidepressant-like effect of ADDCH1 (30 mg/kg, i.p.) in the TST was prevented by pre-treatment of mice with methysergide (2 mg/kg, i.p.), a non-selective serotonin receptor antagonist, p-chlorophenylalanine methylester (pCPA, 100 mg/kg, i.p.), an inhibitor of serotonin synthesis, prazosin (62.5 microg/kg, i.p.), an alpha1-adrenoceptor antagonist, or yohimbine (1 mg/kg, i.p.), an alpha2-adrenoceptor antagonist. In contrast, the antidepressant-like effect of ADDCH2 was antagonized only by yohimbine (1 mg/kg) or haloperidol (50 microg/kg, i.p.), a dopamine D2/D3/D4 receptor antagonist, and was not affected by methysergide, pCPA or prazosin. Altogether, the present results strongly suggest the differential involvement of monoaminergic systems, serotonin/noradrenaline (ADDCH1) and noradrenaline/dopamine (ADDCH2) pathways, respectively, in the antidepressant-like effect of dibenzosuberone compounds.
1. The effects of the 5-HT1A receptor agonist, (8-OH-DPAT), alone and in combination with the selective 5-HT1A antagonist, WAY-100635, were assessed in Fischer-344 rats in an 8-arm radial maze. 2. At a dose of 1.0 mg/kg, 8-OH-DPAT significantly reduced both efficiency of performance (% correct arm entries) and response rate (arms/min) compared with the saline condition. 3. These effects were completely blocked by WAY-100635 which by itself had no effect on efficiency or response rate. 4. WAY-100635 inhibits 8-OH-DPAT-induced impairment in radial maze performance.
Many antipsychotic drugs cause QT prolongation, although the effect differs based on the particular drug. We sought to determine the potential for antipsychotic drugs to prolong the QTc interval (>470 ms in men and >480 ms in women) using the Bazett formula in a "real-world" setting by analyzing the electrocardiograms of 1017 patients suffering from schizophrenia. Using logistic regression analysis to calculate the adjusted relative risk (RR), we found that chlorpromazine (RR for 100 mg=1.37, 95% confidence interval (CI)=1.14 to 1.64; p<.005), intravenous haloperidol (RR for 2 mg=1.29, 95% CI=1.18 to 1.43; p<.001), and sultopride (RR for 200 mg=1.45, 95% CI=1.28 to 1.63; p<.001) were associated with an increased risk of QTc prolongation. Levomepromazine also significantly lengthened the QTc interval. The second-generation antipsychotic drugs (i.e., olanzapine, quetiapine, risperidone, and zotepine), mood stabilizers, benzodiazepines, and antiparkinsonian drugs did not prolong the QTc interval. Our results suggest that second-generation antipsychotic drugs are generally less likely than first-generation antipsychotic drugs to produce QTc interval prolongation, which may be of use in clinical decision making concerning the choice of antipsychotic medication.
Abnormal brain structure of frontal and temporal brain regions has been suggested to occur in patients with schizophrenia who have frequent auditory verbal hallucinations (AVH). However, it is unknown whether this is specific to this patient subgroup. This study tested the hypothesis that frontotemporal gray matter volume changes would characterize patients with persistent AVH (pAVH) in contrast to healthy controls and patients without AVH. Using structural magnetic resonance imaging at 3T, we studied 20 patients with schizophrenia and 14 matched healthy controls. Ten patients were classified as having chronic and treatment resistant AVH, whereas the remaining 10 patients either never had AVH in the past or were in full remission with regard to AVH (nAVH). Using a multivariate statistical technique for structural data, i.e. "source-based morphometry" (SBM), we investigated naturally grouping patterns of gray matter volume variation among individuals, the magnitude of their expression between-groups and the relationship between gray matter volume and AVH-specific measures. SBM identified a reduction of medial and inferior frontal, insular and bilateral temporal gray matter volume between pAVH and nAVH. This pattern did not differ between nAVH patients and controls and was associated with "physical" AVH characteristics (such as symptom duration, location, frequency and intensity) in the pAVH patient group. These results suggest that a pattern of lower gray matter volume in medial frontal and bilateral temporal cortical regions differentiates between patients with persistent AVH and non-hallucinating patients. Moreover, the data support a specific role of this neural pattern in AVH symptom expression.
The selective serotonin reuptake inhibitors (SSRIs) have emerged as a major therapeutic advance in psychopharmacology. As a result, the discovery of these agents marks a milestone in neuropsychopharmacology and rational drug design, and has launched a new era in psychotropic drug development. Prior to the SSRIs, all psychotropic medications were the result of chance observation. In an attempt to develop a SSRI, researchers discovered a number of nontricyclic agents with amine-uptake inhibitory properties, acting on both noradrenergic and serotonergic neurons with considerable differences in potency. A given drug may affect one or more sites over its clinically relevant dosing range and may produce multiple and different clinical effects. The enhanced safety profile includes a reduced likelihood of pharmacodynamically mediated adverse drug-drug interactions by avoiding affects on sites that are not essential to the intended outcome. SSRIs were developed for inhibition of the neuronal uptake pump for serotonin (5-HT), a property shared with the TCAs, but without affecting the other various neuroreceptors or fast sodium channels. The therapeutic mechanism of action of SSRIs involves alteration in the 5-HT system. The plethora of biological substrates, receptors and pathways for 5-HT are candidates to mediate not only the therapeutic actions of SSRIs, but also their side effects. A hypothesis to explain these immediate side effects is that 5-HT is increased at specific 5-HT receptor subtypes in discrete regions of the body where the relevant physiologic processes are regulated. Marked differences exist between the SSRIs with regard to effects on specific cytochrome P450 (CYP) enzymes, and thus the likelihood of clinically important pharmacokinetic drug-drug interactions. Although no clear relationship exists between the clinical efficacy, plasma concentration of SSRIs, nor any threshold that defines toxic concentrations, but therapeutic drug monitoring (TDM) may be useful in special populations, such as in elderly patients, poor metabolizers (PM) of sparteine (CYP2D6) or mephenytoin (CYP2C19), and patients with liver and kidney impairment. Several meta-analyses have reviewed the comparative efficacy of TCAs and SSRIs, and concluded that both TCAs and SSRIs have similar efficacy in the treatment of depression. SSRIs have demonstrated better efficacy and tolerability in the treatment of obsessive compulsive disorder (OCD). They have also been found to be effective in the treatment for social anxiety disorder both in reducing total levels of social anxiety and in improving overall clinical condition. The benefit of SSRIs in anorexia nervosa (AN) is apparently short-term unless medication is given in the context of nutritional or behavioral therapy. No single antidepressant can ever be recommended for every patient, but in a vast majority of patients, SSRIs should be considered as one of the first-line drugs in the treatment of depression.
1. The presence of Alzheimer-type neurofibrillary pathology and amyloid deposits within the brains of 27 aged non-demented subjects was investigated by immunoblotting and immunohistochemistry using antibodies directed against pathological Tau proteins 55, 64 and 69 and beta A4 respectively. 2. The abnormal Tau triplet, a biochemical marker of neurofibrillary degeneration was quantified by western blot and densitometric analysis in several cortical areas including the entorhinal cortex (EC), hippocampus and Brodmann areas (BA) 38, 20, 22, 35, 9, 44 and 39. 3. The abnormal Tau triplet was detected in the EC and the hippocampus of most of the controls aged over 70 years. In few control cases abnormal Tau proteins were also detected in the isocortex, in BA38 alone or also in BA20. Some cases and especially those with Tau pathology in the temporal lobe contained numerous senile plaques (SP) in the neocortex. 4. The authors conclude that control cases with Tau pathology in the temporal lobe and numerous SP in the neocortex were likely to be subclinical stages of AD whereas others with Tau pathology exclusively detected in the EC and hippocampus and without or few SP in the neocortex were related to normal aging.
Elderly, community residing subjects (N = 106; mean age = 70.6 +/- 6.02 years) with cognitive functioning consistent with normal aging or dementia of the Alzheimer's type (DAT), were followed over a 3.6 year mean interval (range = 2.78 to 5.12 years). All subjects were assessed at baseline on the Global Deterioration Scale (GDS), a global clinical instrument reflecting the continuum of cognitive dysfunction from normal aging to severe DAT. At follow-up subjects were reassessed with respect to mortality, institutionalization and clinical change, defined as at least a two-point change on the 7-point GDS. Our results suggest that patients at deterioration levels GDS greater than or equal to 4, are more likely to show negative outcomes, specifically, institutionalization (Ps less than .001), death (Ps less than .01), or, for the community residing remainder, clinical deterioration (Ps less than .05), than subjects from less impaired (GDS = 2 or GDS = 3) subject groups. Seventy-six per cent of subjects at deterioration levels four or greater (N = 34) had negative outcomes at follow-up, whereas ninety percent of subjects with deterioration levels less than four (N = 72) did not.
This review describes the animal behavior models that provide insight into the mechanisms underlying the critical differences between the actions of typical vs. atypical antipsychotic drugs. Although many of these models are capable of differentiating between antipsychotic and other psychotropic drugs, only a few seem to be able to differentiate between typical and atypical antipsychotics, such as the paw test and the phencyclidine (PCP)-induced disruption of prepulse inhibition (PPI) of startle in rats. Moreover, there is an urgent need for animal models focusing more on the negative and the cognitive symptoms. Hence, improved animal models are crucial for developing better treatments for schizophrenia.
A review of the history of antipsychotics reveals that while the therapeutic effects of chlorpromazine and reserpine were discovered and actively researched almost concurrently, subsequent drug development has been restricted to drugs acting on postsynaptic receptors rather than modulation of dopamine release. The fundamental property of atypical antipsychotics is their ability to produce an antipsychotic effect in the absence of extrapyramidal side effects (EPS) or prolactin elevation. Modulation of the dopamine D2 receptor remains both necessary and sufficient for antipsychotic drug action, with affinity to the D2-receptor being the single most important discriminator between a typical and atypical drug profile. Most antipsychotics, including atypical antipsychotics, show a dose-dependent threshold of D2 receptor occupancy for their therapeutic effects, although the precise threshold is different for different drugs. Some atypical antipsychotics do not appear to reach the threshold for EPS and prolactin elevation, possibly accounting for their atypical nature. To link the biological theories of antipsychotics to their psychological effects, a hypothesis is proposed wherein psychosis is a state of aberrant salience of stimuli and ideas, and antipsychotics, via modulation of the mesolimbic dopamine system, dampen the salience of these symptoms. Thus, antipsychotics do not excise psychosis: they provide the neurochemical platform for the resolution of symptoms. Future generations of antipsychotics may need to move away from a "one-size-fits-all polypharmacy-in-a-pill" approach to treat all the different aspects of schizophrenia. At least in theory a preferred approach would be the development of specific treatments for the different dimensions of schizophrenia (e.g., positive, negative, cognitive, and affective) that can be flexibly used and titrated in the service of patients' presenting psychopathology.
There is compelling evidence that impaired corticosteroid receptor function is the key mechanism in the pathogenesis of depression resulting in a dysfunctional stress hormone regulation, which can be most sensitively detected with the combined dexamethasone (dex)/corticotropin releasing hormone (CRH) test. Treatment with different kinds of antidepressants is associated with a reduction of the hormonal responses to the combined dex/CRH test suggesting normalization of impaired corticosteroid receptor signaling as the final common pathway of these drugs. Consequently, the combined dex/CRH test is suggested as a screening tool to decide whether new compounds designed as antidepressants provide sufficient efficacy to normalize corticoid receptor signaling in depressed patients. We summarize own data and findings from the literature suggesting that (1) the neuroendocrine response to the combined dex/CRH test is elevated during a major depressive episode, but (2) tends to normalize after successful treatment. (3) Favorable response to antidepressant treatment can be predicted by determining the dex suppresser status on admission. For optimal prediction of non-response to antidepressant treatment, however, the results of a second dex/CRH test are necessary. These findings, together with the fact that impaired corticosteroid receptor signaling is considered as key mechanism of the pathogenesis in depression, support the suitability of the combined dex/CHR test as a surrogate marker for treatment response in depression. In conclusion, the combined dex/CRH test is a promising candidate to serve as a screening tool for the antidepressive effects of new compounds in clinical drug trials. Furthermore, the test appears to be capable of predicting the individual likelihood to respond to a current antidepressant treatment. If a drug treatment fails to normalize the outcome of the combined dex/CRH test, a change of the treatment strategy is recommended. Further systematic research is required and already ongoing to confirm the suitability of the combined dex/CRH test as a surrogate marker in depression.
1. RNA was purified from postmortem human brains, and the poly A+ RNA was isolated by oligo dT cellulose. 2. Double stranded cDNA was synthesized using reverse transcriptase, RNAse H and DNA polymerase. 3. cDNA was cloned in the lambda GT 11 expression vector, and libraries containing between 1 and 2 millions clones were obtained. 92 to 98% of the plaques contained a recombinant phage. 4. Such libraries will allow the molecular characterization of cDNA and corresponding proteins which play a key role in brain functions and in particular which could be involved in the etiology of Alzheimer's dementia.
The chronic use of drugs, including psychostimulants such as cocaine and amphetamine, has been associated with low D2/3 dopamine receptor availability, which in turn has been linked to poor clinical outcome. In contrast, recent studies focused on the D3 receptor (a member of the D2-like receptor family) suggest that chronic exposure to stimulant drugs can up-regulate this receptor subtype, which, in preclinical models, is linked to dopamine system sensitization - a process hypothesized to contribute to relapse in addiction. In this mini review we present recent human data suggesting that the D3 receptor may contribute to core features of addiction, and discuss the usefulness of the PET imaging probe [(11)C]-(+)-PHNO in investigating this question.
1. In two open studies using patients with intractable epilepsy, the effects of CGP 11.952, a triazolyl benzophenone, on cognitive functioning were assessed by means of a computerized neuropsychological battery. 2. In the first study CGP 11.952 turned out to have a positive effect on information processing speed, perceptual sensitivity and preciseness of responses. 3. Negative effects were found on reaction time. 4. In the second study this latter effect was less clear. 5. A striking result was the less negative effect on memory consolidation under influence of CGP 11.952 in comparison with other benzodiazepines.
Depression is a frequently encountered non-motor feature of Parkinson's disease (PD) and it can have a significant impact on patient's quality of life. Considering the differential pathophysiology of depression in PD, it prompts the idea that a degenerated nigrostriatal system plays a role in depressive-like behaviors, whilst animal models of PD are employed. Therefore, we addressed the question of whether dopamine (DA) depletion, promoted by the neurotoxins 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), 6-hydroxydopamine (6-OHDA), lipopolysaccharide (LPS) and rotenone are able to induce depressive-like behaviors and neurotransmitters alterations similarly that encountered in PD. To test this rationale, we performed intranigral injections of each neurotoxin, followed by motor behavior, depressive-like behaviors, histological and neurochemical tests. After the motor recovery period, MPTP, 6-OHDA and rotenone were able to produce anhedonia and behavioral despair. These altered behavioral responses were accompanied by reductions of striatal DA, homovanillic acid (HVA) and 3,4-dihydroxyphenylacetic acid (DOPAC) restricted to the 6-OHDA group. Additionally, decreases on the hippocampal serotonin (5-HT) content were detected for the MPTP, 6-OHDA and rotenone groups. Notably, strong correlations were detected among the groups when 5-HT and DA were correlated with swimming (r=+0.97; P=0.001) and immobility (r=-0.90; P=0.012), respectively. Our data indicate that MPTP, 6-OHDA and rotenone, but not LPS were able to produce depressive-like behaviors accompanied primarily by hippocampal 5-HT reductions. Moreover, DA and 5-HT strongly correlated with "emotional" impairments suggesting an important participation of these neurotransmitters in anhedonia and behavioral despair after nigral lesions promoted by the neurotoxins.
Theoretically, central acetylcholinesterase inhibitors (CAIs) could alleviate at least some of the main symptoms of chronic traumatic brain injury (TBI). The aim of this report is to describe clinical experience of the treatment of chronic TBI with these drugs. GENERAL METHODS: From an outpatient clinic material, 111 patients were selected having chronic stable TBI with at least one of the following target symptoms: fatigue, poor memory, diminished attention or diminished initiation. Patients received in random donepezil, galantamine or rivastigmine. The evaluation of the treatment response was based on the subjective view of the patient. As first treatment, 27 patients received donepezil, 30 galantamine and 54 rivastigmine. Altogether 41 patients tried more than one drug, but only three patients tried all three alternatives. In total, 61% of patients had a marked positive response and 39% a modest or no response. The clearest effect was in almost all responders a better vigilance and attention causing better general function. About half of the patients (55%) wanted to continue therapy with one of these drugs. The therapeutic response became very quickly and at low doses. There were no significant differences between the three drugs either in effect or tolerability. The age, sex, type of injury, severity of TBI or elapsed time after injury did not affect the response. The mean dose in maintenance therapy was 7.2 mg od for donepezil, 5.0 mg bid for galantamine and 2.3 mg bid for rivastigmine. Side effects or inadequate therapeutic response were the main causes for discontinuation with nearly equal frequency. Paradoxical responses were seen in some patients. CAIs show a very promising therapeutic potential in the treatment of chronic TBI. There were no significant differences between the three drugs. Large-scale randomised double-blinded placebo-controlled studies are clearly needed.
Although all currently used antipsychotic drugs act as dopamine (DA) D2 receptor antagonists, clozapine, the prototype for atypical antipsychotics, shows superior efficacy, especially regarding negative and cognitive symptoms, in spite of a significantly reduced central D2 receptor occupancy compared with typical (conventional) antipsychotic drugs. Clozapine, as well as several other atypicals, displays significant affinities also for several other neurotransmitter receptors, including other dopaminergic receptors, alpha-adrenergic receptors and different serotonergic and cholinergic receptors, which in several ways may contribute to the clinical effectiveness of the drugs. Preclinical and clinical results suggest a dysregulated mesocorticolimbic DA system in schizophrenia, with an impaired prefrontal DA projection, which may relate to negative and cognitive symptoms, concomitant with an overactive or overreactive striatal DA projection, with bearing on psychotic (positive) symptomatology. Available data suggest that blockage of alpha1-adrenoceptors by antipsychotics may contribute to suppress positive symptoms, especially in acute schizophrenia, whereas alpha2-adrenoceptor blockage, a prominent effect of clozapine and, to some extent, risperidone but not other antipsychotics, may rather be involved in relief of negative and cognitive symptoms. Whereas alpha1-adrenoceptor blockage may act by suppressing, at the presynaptic level, striatal hyperdopaminergia, alpha2-adrenoceptor blockage may act by augmenting and improving prefrontal dopaminergic functioning. Thus, the prominent alpha1- and alpha2-adrenoceptor blocking effects of clozapine may generally serve to stabilize dysregulated central dopaminergic systems in schizophrenia, allowing for improved efficacy in spite of a reduced central D2 receptor occupancy compared with typical antipsychotic drugs.
Addition of linoleic acid (50 microM) to culture medium significantly increases levels of polyunsaturated fatty acids (PUFA) in membrane phospholipids of NIE-115 neuroblastoma. Basal levels of cyclic AMP are elevated significantly in supplemented cells. Exogenous prostaglandins (PG) PGE1 and PGD2 stimulate cAMP formation in NIE-115 neuroblastoma. Supplemented cells produce higher levels of PGE and PGD than do control cultures. Inclusion of cyclooxygenase inhibitors in culture medium does not block elevation of cyclic nucleotide in supplemented cells. Endogenous PG production and receptor activation cannot account for increased cAMP in EFA-supplemented neuroblastoma.
Binding of [3H]methionine-enkephalin to intact N1E-115 neuroblastoma cells (competing ligand: naloxone) revealed a homogenous population of receptors with a density (Bmax) of 79.0 +/- 6.5 fmol/mg protein (mean SEM, N = 3) and an apparent Kd of 5.33 +/- 1.63 mM. The order of displacement of [3H]met-enkephalin was met-/leu-enkephalin greater than naloxone greater than morphine, suggesting that it is of the delta receptor class. Specific binding was heat-labile, stereospecific and sensitive to Na+. Adding met-enkephalin to intact neuroblastoma caused reductions of both basal and prostaglandin E1-stimulated levels of cyclic AMP (41.4 +/- 4.0% (N = 6) and 45.1 +/- 2.4% (N = 3) of control levels, respectively). Maximum inhibition (naloxone-reversible) was observed as low as 10(-7) M met-enkephalin. Preliminary results suggest that cells grown in cholesterol-supplemented medium show reduced binding of [3H]met-enkephalin.
Serotonin (5-HT)-receptor-based mechanisms have been postulated to play a critical role in the action of the new generation of antipsychotic drugs (APDs) that are usually referred to as atypical APDs because of their ability to achieve an antipsychotic effect with lower rates of extrapyramidal side effects (EPS) compared to first-generation APDs such as haloperidol. Specifically, it has been proposed by Meltzer et al. [J. Pharmacol. Exp. Ther. 251 (1989) 238] that potent 5-HT2A receptor antagonism together with weak dopamine (DA) D2 receptor antagonism are the principal pharmacologic features that differentiate clozapine and other apparent atypical APDs from first-generation typical APD. This hypothesis is consistent with the atypical features of quetiapine, olanzapine, risperidone, and ziprasidone, which are the most common treatments for schizophrenia in the United States and many other countries, as well as a large number of compounds in various stages of development. Subsequent research showed that 5-HT1A agonism may be an important consequence of 5-HT2A antagonism and that substitution of 5-HT1A agonism for 5-HT2A antagonism may also produce an atypical APD drug when coupled with weak D2 antagonism. Aripiprazole, the most recently introduced atypical APD, and a D2 receptor partial agonist, may also owe some of its atypical properties to its net effect of weak D2 antagonism, 5-HT2A antagonism and 5-HT1A agonism [Eur. J. Pharmacol. 441 (2002) 137]. By contrast, the alternative "fast-off" hypothesis of Kapur and Seeman [Am. J. Psychiatry 158 (2001) 360] applies only to clozapine and quetiapine and is inconsistent with the "slow" off rate of most atypical APDs, including olanzapine, risperidone and ziprasidone. 5-HT2A and 5-HT1A receptors located on glutamatergic pyramidal neurons in the cortex and hippocampus, 5-HT2A receptors on the cell bodies of DA neurons in the ventral tegmentum and substantia nigra and GABAergic interneurons in the cortex and hippocampus, and 5-HT1A receptors in the raphe nuclei are likely to be important sites of action of the atypical APDs. At the same time, evidence has accumulated for the important modulatory role of 5-HT2C and 5-HT6 receptors for some of the effects of some of the current APDs. Thus, 5-HT has joined DA as a critical target for developing effective APDs and led to the search for novel drugs with complex pharmacology, ending the exclusive search for single-receptor targets, e.g., the D3 or D4 receptor, and drugs that are selective for them.
Unstimulated production of interleukine-6 (IL-6) is known to be enhanced in patients affected by a major depressive episode. Recent studies supported a role for basal IL-6 levels in predicting response to antidepressant drug treatments. In a sample of 10 consecutively admitted drug-free bipolar depressed inpatients, we investigated the possible correlation between unstimulated pretreatment production of IL-6 and antidepressant response to a night of total sleep deprivation (TSD) followed by a night of sleep phase advance (SPA), a nonpharmacologic treatment which is known to rapidly improve depressive symptomatology. Changes in perceived mood during treatment were recorded with self-administered Visual Analogue Scales (VAS). We observed a significant inverse correlation between IL-6 serum levels and VAS scores after treatment, meaning that higher IL-6 values before treatment were associated with worse response. This finding is in agreement with previous studies about amitriptyline and lithium antidepressant treatments. Our preliminary finding confirms the clinical value of IL-6 baseline concentration as a predictor of response to antidepressant treatment.
Glutathione levels in the study groups. 
The activities of the RBC antioxidant enzymes in the study groups. 
There is substantial evidence found in the literature that supports the fact that the presence of oxidative stress may play an important role in the physiopathology of schizophrenia. Previous studies have reported the occurrence of impairments in the glutathione levels and the activities of the antioxidant enzymes in patients suffering from schizophrenia. However, most of these studies were performed on treated patients. The present study evaluated treated schizophrenic patients (n=52) along with neuroleptic-free or untreated schizophrenic patients (n=36) and healthy controls (n=46). The blood glutathione levels: total glutathione (GSHt), reduced glutathione (GSHr), and oxidized glutathione (GSSG) as well as the activities of the antioxidant enzymes: superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase (CAT) were measured. The psychopathology of the patients was assessed through the Clinical Global Impressions-severity (CGI-severity). The tests revealed that in comparison with the healthy controls, the schizophrenic patients showed significantly lower levels of GSHr, SOD, and CAT. Among the schizophrenic patients, the activities of the antioxidant enzymes SOD and CAT were recorded to be significantly lower in untreated patients than in the treated ones. In addition, the levels of both GSHt and GSHr were found to be inversely correlated with the obtained CGI-severity score. These results evidently suggest that a decrease in the glutathione levels and the activities of the antioxidant enzymes in patients diagnosed with schizophrenia is not related to neuroleptic treatment and could be considered as a biological indicator of the degree of severity of the symptoms of schizophrenia.
Limbic dysfunction and hypothalamo-pituitary-adrenocortical (HPA) axis dysregulation are key features of affective disorders. The following review summarizes our current understanding of the relationship between limbic structures and control of ACTH and glucocorticoid release, focusing on the hippocampus, medial prefrontal cortex and amygdala. In general, the hippocampus and anterior cingulate/prelimbic cortex inhibit stress-induced HPA activation, whereas the amygdala and perhaps the infralimbic cortex may enhance glucocorticoid secretion. Several characteristics of limbic-HPA interaction are notable: first, in all cases, the role of given limbic structures is both region- and stimulus-specific. Second, limbic sites have minimal direct projections to HPA effector neurons of the paraventricular nucleus (PVN); hippocampal, cortical and amygdalar efferents apparently relay with neurons in the bed nucleus of the stria terminalis, hypothalamus and brainstem to access corticotropin releasing hormone neurons. Third, hippocampal, cortical and amygdalar projection pathways show extensive overlap in regions such as the bed nucleus of the stria terminalis, hypothalamus and perhaps brainstem, implying that limbic information may be integrated at subcortical relay sites prior to accessing the PVN. Fourth, these limbic sites also show divergent projections, with the various structures having distinct subcortical targets. Finally, all regions express both glucocorticoid and mineralocorticoid receptors, allowing for glucocorticoid modulation of limbic signaling patterns. Overall, the influence of the limbic system on the HPA axis is likely the end result of the overall patterning of responses to given stimuli and glucocorticoids, with the magnitude of the secretory response determined with respect to the relative contributions of the various structures.
Iloperidone is a novel atypical antipsychotic compound currently under clinical development for the treatment of psychotic disorders. In radioligand binding studies, iloperidone binds with high affinity to serotonin (5-HT) 5-HT2A and noradrenaline alpha1 and alpha2C receptors [Neuropsychopharmacology (2001) 25, 904-914]. The human metabolism of iloperidone generates two major metabolites, P88-8991 and P95-12113. The aim of this study was to compare the receptor affinity profile of P88-8991 and P95-12113 with that of the parent compound. The receptor affinity profile of P88-8991 is comparable to that of iloperidone. This metabolite binds to the following monoamine receptors (pKi values in nM): serotonin 5-HT2A receptors (9.56), adrenergic alpha1 (8.08) and alpha2C (7.79) receptors, and D2A receptors (7.80). Lower affinity is seen for other dopamine, serotonin, alpha2-adrenergic and histamine H1 receptors. In contrast, P95-12113 shows affinity for 5-HT2A receptors (pKi 8.15; which is 60-fold lower than that of iloperidone), adrenergic alpha1 (7.67), alpha2C (7.32) and alpha2B (7.08) receptors. Given this affinity profile, and the observation that P95-12113 does not readily cross the blood-brain barrier, it is unlikely that this metabolite contributes to the therapeutic effect of iloperidone in patients with schizophrenia. However, the comparable receptor binding profile of P88-8991 indicates that it is likely to contribute to the clinical profile of iloperidone.
We have characterized and quantified specific binding of [3H]-flunitrazepam (FNZ; (benzodiazepine), [3H]-naloxone (NAL; (opiate) and [3H] CGP-12177(CGP; (beta-adrenergic) to thick slices (230-400 micron) of mouse and rat brain. The binding sites are stereospecific, saturable and of high affinity. In all cases, the binding of the ligands is readily reversible and demonstrates the appropriate drug specificity. In mouse brain [3H]-NAL binding is elevated by chronic treatment with naloxone (via capsules). We have been unsuccessful in quantifying beta adrenoreceptors with the archetypal ligand [3H]-dihydroalprenolol (DHA). However, the use of [3H]-CGP 12177 enabled us to detect high-affinity beta adrenoreceptors in brain slices. [3H]-CGP also permits the demonstration of rapid and reversible agonist-induced down-regulation (internalization) of beta binding sites. We have been successful in quantifying beta adrenergic sites in single pineal glands of rat and hamster.
1. Animal models of human behavior and disease are commonly used and have contributed significantly to progress in understanding the physiological mechanisms of both normal function and disease, and in the development of effective therapies. 2. Little attention has been given, however, to the scientific and ethical implications of choosing a particular animal model. 3. This paper discusses the rationale for the selection of particular animal models that have been chosen to study certain human diseases or behaviors, and provides examples to illustrate how underlying assumptions about methods and about physiological mechanisms and other relevant features of the disease or behavior of interest are embedded in the choice of an animal model. 4. Although these assumptions influence the direction of research, they are rarely analyzed explicitly, or evaluated empirically. The authors recommend that assumptions should be clearly stated and that, whenever possible, they be specifically and thoroughly evaluated empirically.
Altered serotonin (SERT) and dopamine transporter (DAT) densities have been recorded in major depression. Atypical depression (ATD) has been suggested to be connected to decreased serotonergic transmission, but no studies have been published on the association between brain serotonin transporter density and ATD. PATIENTS with depression (n=29) were divided into three groups according to DSM-IV criteria: atypically depressed, melancholic patients, and "undifferentiated" patients. Depressive symptoms were evaluated with the 29-item Hamilton Depression Rating Scale (HAM-D-29). Single photon emission computed tomography (SPECT) with [(123)I]nor-beta-CIT was used to evaluate serotonin transporter density (SERT) in the midbrain and dopamine transporter density (DAT) in the striatum of patients and healthy controls (n=18). All subgroups except those with undifferentiated depression had lower SERT densities compared to controls. No significant differences were found in the densities between the subgroups. Atypical scores of HAM-D-29 were associated with SERT densities in the midbrain (beta=-0.40, t=-2.3, p=0.03), even after adjustment for age, gender and HAM-D-21 scores (beta=-0.39, t=-2.32, p=0.03). The association between atypical scores of HAM-D-29 and midbrain SERT densities suggests a relationship between serotonergic dysfunction and ATD.
Objective: The aim of this study was to compare striatal dopaminergic D2 receptor occupancy (D2 RO) induced by ziprasidone and haloperidol and its relationship with clinical response and extrapyramidal side effects (EPS) in patients with acute psychosis exacerbation. Method: Twenty patients hospitalized with an acute psychosis exacerbation were randomised in a single-blind study to receive either ziprasidone (80-120 mg/day) or haloperidol (5-20 mg/day) for more than 2 weeks. When stable doses were achieved, data on 123I-IBZM single-photon emission computed tomography (SPECT), as well as data on clinical efficacy (positive and negative symptoms scale [PANSS]) and EPS (Simpson Angus scale [SAS]), were compared between the two groups of patients. Clinical response was defined as a percentage of change of >30% in PANSS. Striatal D2 RO and clinical data were also compared between responders and nonresponders on each treatment group. Results: All patients on haloperidol and four patients on ziprasidone showed EPS. Mean D2 RO was significantly higher in the haloperidol (74.7+/-3.5) than in the ziprasidone (60.2+/-14.4) group (Mann Whitney U-test [M-W U-test] 8.50; p=0.002). Five patients were responders, and five were nonresponders on each group of treatment. Haloperidol responders and nonresponders did not differ in D2 RO, duration of treatment, doses or EPS. Ziprasidone responders were on higher doses than nonresponders and showed higher D2 RO although below 74%. A positive correlation of ziprasidone D2 RO was found with dose (r Spearman 0.87; p=0.001) and with SAS scores (r Spearman 0.88; p=0.001). Conclusions: Ziprasidone induces lower D2 RO and EPS than haloperidol, which is consistent with an atypical antipsychotic profile. A direct relationship of ziprasidone D2 RO with dose, clinical efficacy and EPS has been found in this study. These data suggest that high ziprasidone doses might be more beneficial in patients with psychosis exacerbation and claim for caution regarding EPS appearance with such high dosages.
1. Previous experiments in this laboratory found that striatal [3H]WIN 35428 binding was increased in post mortem specimens from human cocaine users (Little et al, 1993a). Although structurally similar, preliminary studies have suggested that [3H]WIN 35428 and the related cocaine congener [125I]RTI-55 differ in some respects pharmacologically. 2. The present experiments tested the hypothesis that striatal [125I]RTI-55 binding would be increased, as was [3H]WIN 35428 binding, in post mortem specimens from cocaine users compared to matched controls. 3. However, computer-generated parameters derived from saturation experiments found only trends toward increased Bmax and decreased affinity (increased KD) in the cocaine users. The magnitude of the increases were notably smaller than the statistically significant increases previously found in high affinity [3H]WIN 35428 binding in these same subjects. 4. Evidence from the present and earlier experiments suggests that cocaine exposure may induce conformational changes in the dopamine transporter.
1. Binding sites for the R and S enantiomers of the 5HT2 agonist DOI (2,5-dimethoxy-4-iodophenylisopropylamine) were identified in rat brain using quantitative in-vitro autoradiography and compared with [125I]-LSD binding. 2. In most regions of the brain, binding density of the less active isomer [125I]S-DOI was 15 to 85% of that exhibited by the active [125I]R-DOI isomer. 3. Cortical membrane preparations exhibited two binding sites, of the enantiomers with high (KdH) and low (KdL) affinity constants of 1.2 +/- 0.02 nM and 29 +/- 7 nM for the [125I]R-DOI and 2.1 +/- 0.2 nM and 18 +/- 4 nM for [125I]S-DOI respectively. The respective high (BmaxH) and low (BmaxL) binding densities were 92 +/- 10 and 536 +/- 164 fmol/mg protein for the [125I]R-DOI and 67 +/- 19 and 245 +/- 60 fmol/mg protein for [125I]S-DOI. 4. Our results correlate with regional distribution of 5HT2 receptors reported in previous studies and indicate that DOI and its congeners have potential clinical applications for the in-vivo localization of 5HT2 receptors.
1. Antagonists at 5-HT3 receptors have shown activity in animal models of mental illness, however, few radiolabeled 5-HT3 ligands are available for preclinical studies. MIZAC, an analogue of the selective 5-HT3 antagonist, zacopride, binds with high affinity (1.3-1.5 nM) to CNS 5-HT3 sites. The authors report here the selectivity of MIZAC for these sites in rat brain homogenates. 2. Ninety-seven percent of total specific binding of [125I]MIZAC (0.1 nM) of was displaced by bemesetron (3 microM), a selective 5-HT3 antagonist. Competition studies using ligands with known affinities for 5-HT3 sites give a high correlation with reported pKi values (r2 0.98). Bemesetron displaceable binding has a regional distribution consistent with that of the 5-HT3 receptor, i.e. highest in cortex and hippocampus, and lowest in striatum and cerebellum. 3. Potent antagonists present at concentrations sufficient to occupy 95% of other 5-HT receptor populations (1A, 1B, 1D, 2A, 2B, 2C, 5A, 5B, 6, and 7) showed minimal ability to displace [125I]MIZAC binding (3 nM). Specificity studies using radioligand binding assays selective for 5-HT4, 5-HT6, and 5-HT7 receptors, and for binding sites of other neurotransmitters indicate a high degree of selectivity of [125I]MIZAC for the 5-HT3 receptor. 4. [125I]MIZAC binds to an apparent low affinity (benzac) site having a unique pharmacology. Low affinity binding was displaceable by benztropine, but not by other muscarinic agents nor inhibitors of dopamine uptake. The regional distribution of the low affinity site differed markedly from that of the high affinity site. The apparent affinity of [125I]MIZAC for the benzac site is two orders of magnitude lower than for the 5-HT3 receptor. Given its high selectivity for 5-HT3 binding sites, [125I]MIZAC appears to be a promising ligand for labeling 5-HT3 receptors in vitro and in vivo.
Unraveling the pathways and neurobiological mechanisms that underlie the regulation of physical and emotional stress responses in humans is of critical importance to understand vulnerability and resiliency factors to the development of a number of complex physical and psychopathological states. Dysregulation of central stress response circuits have been implicated in the establishment of conditions as diverse as persistent pain, mood and personality disorders and substance abuse and dependence. The present review examines the contribution of the endogenous opioid system and mu-opioid receptors to the modulation and adaptation of the organism to challenges, such as sustained pain and negative emotional states, which threaten its internal homeostasis. Data accumulated in animal models, and more recently in humans, point to this neurotransmitter system as a critical modulator of the transition from acute (warning signals) to sustained (stressor) environmental adversity. The existence of pathways and regulatory mechanisms common to the regulation of both physical and emotional states transcend classical categorical disease classifications, and point to the need to utilize dimensional, "symptom"-related approximations to their study. Possible future areas of study at the interface of "mind" (cognitive-emotional) and "body" (physical) functions are delineated in this context.
Top-cited authors
Michael Maes
  • King Chulalongkorn Memorial Hospital
Kenji Hashimoto
  • Abbott Laboratories
Flavio Kapczinski
  • Hospital de Clínicas de Porto Alegre
Masaomi Iyo
  • Chiba University
Yong-Ku Kim
  • Korea University