[Show abstract][Hide abstract] ABSTRACT: The interaction between antinociception induced by CB1 agonist and muscarinic receptor modulators has not been studied yet. In the present study, the effect of pilocarpine (a muscarinic agonist) and atropine (a muscarinic antagonist) on arachidonylcyclopropylamide (ACPA, a CB1 agonist) induced antinociception was studied in mice. In this study the antinociceptive effect of intracerebroventricular administration of ACPA (0.001–2 μg/mice) or intraperitoneal injection of pilocarpine (2.5–20 mg/kg) or atropine (1 and 5 mg/kg) were studied individually. Then the effect of co-administration of pilocarine (2.5 mg/kg) or atropine (5 mg/kg) and ACPA (0.001–2 μg/mice) were studied as well. ACPA and pilocarpine induced antinociception in mice but atropine did not. Pilocarpine potentiated but atropine antagonized the antinociceptive effect of ACPA. It is concluded that ACPA induced antinociception is influenced by muscarinic receptor modulators in mice.
[Show abstract][Hide abstract] ABSTRACT: Background: Sleep deprivation (SD) is emerging as a hot topic due to its health concerns. There are compelling reasons for a tremendous interest in neuroscience of sleep in recent years.Objectives: We aimed to evaluate how total sleep deprivation (TSD) and chronic partial sleep restriction (CPSR) might affect memory,
anxiety-related behaviors, and the serum level of neurochemical markers such as brain-derived neurotrophic factor (BDNF) and corticosterone in a rat model.Materials and Methods: The disk-over-water (DOW) apparatus was employed to induce TSD and CPSR in male Wistar rats. The six study arms were as follows: cage control, 48 hours; cage control, seven days; DOW control, 48 hours; DOW control, seven days, TSD, and CPSR. Elevated plus-maze (EPM) was used to measure parameters (percentage of OAT, percentage of OAE, and locomotor activity) corresponding to anxiety and aversive memory. To measure serum BDNF and corticosterone levels using the ELISA method, blood samples were drawn from all rats on the fourth day at 5 P.M.Results: Our results demonstrated that TSD (P < 0.001) and CPSR (P < 0.001) induce memory impairment while exert anxiolytic-like effects in comparison with controls. Data showed that CPSR causes more memory impairment and anxiolytic-like effect in comparison to TSD (P < 0.001).These interventions however, did not alter the locomotor activity. Serum corticosterone level raised dramatically in CPSR rats in comparison to TSD and controls. Although the difference in serum BDNF level between TSD and CPSRarms was insignificant, it was markedly decreased in comparison to corresponding controls (P < 0.001).Conclusions: Our findings suggest the more pronounced effect of CPSR rather than TSD in impairing aversive memory and reducing anxiety. Decreased BDNF and peaked corticosterone level in TSD and CPSR suggest the probable inflammatory processes involved in possible insults to the brain caused by SD.
[Show abstract][Hide abstract] ABSTRACT: Background: There is evidence that cognitive functions are affected by some liver diseases such as cholestasis. Bile duct ligation induces cholestasis as a result of impaired liver function and cognition. This research investigates the effect of cholestasis progression on memory function in bile duct ligation rats.
Materials and Methods: Male Wistar rats were randomly divided into five groups, which include: control group for BDL-7, control group for BDL-21, sham group (underwent laparotomy without bile duct ligation), BDL-7 group (7 days after bile duct ligation), and BDL-21 group (21 days after bile duct ligation). Step-through passive avoidance test was employed to examine memory function. In all groups, short-term (7 days after foot shock) and long-term memories (21 days after foot shock) were assessed.
Results: Our results showed that liver function significantly decreased with cholestasis progression (P < 0.01). Also our findings indicated BDL-21 significantly impaired acquisition time (P < 0.05). Memory retrieval impaired 7 (P < 0.05) and 21 days (P < 0.001) after foot shock in BDL-7 and BDL-21 groups, respectively.
Conclusion: Based on these findings, liver function altered in cholestasis and memory (short-term and long-term memory) impaired with cholestasis progression in bile duct ligation rats. Further studies are needed to better insight the nature of progression of brain damage in cholestatic disease.
[Show abstract][Hide abstract] ABSTRACT: In the present study, we investigated the possible role of the dorsal hippocampal dopamine D1 receptors on scopolamine-induced amnesia as well as scopolamine state-dependent memory in adult male Wistar rats. Animals were bilaterally implanted with chronic cannulae in the CA1 regions of the dorsal hippocampus, trained in a step-through type inhibitory avoidance task, and tested 24 h after training for their step-through latency. Results indicated that pre-training or pre-test intra-CA1 administration of scopolamine (1.5 and 3 μg/rat) dose-dependently reduced the step-through latency, showing an amnestic response. The pre-training scopolamine-induced amnesia (3 μg/rat) was reversed by the pre-test administration of scopolamine, indicating a state-dependent effect. Similarly, the pre-test administration of dopamine D1 receptor agonist, SKF 38393 (1, 2 and 4 μg/rat, intra-CA1), could significantly reverse the scopolamine-induced amnesia. Interestingly, administration of an ineffective dose of scopolamine (0.25 μg/rat, intra-CA1) before different doses of SKF 38393, blocked the reversal effect of SKF 38393 on the pre-training scopolamine-induced amnesia. Moreover, while the pre-test intra-CA1 injection of the dopamine D1 receptor antagonist, SCH 23390 (0.1 and 0.5 μg/rat, intra-CA1), resulted in apparent memory impairment, microinjection of the same doses of this agent inhibited the scopolamine-induced state-dependent memory. These results indicate that the dorsal hippocampal (CA1) dopamine D1 receptors may potentially play an important role in scopolamine-induced amnesia as well as the scopolamine state-dependent memory. Furthermore, our results propose that dopamine D1 receptor agonist, SKF 38393 reverses the scopolamine induced amnesia via acetylcholine release and possibly through the activation of muscarinic receptors.
[Show abstract][Hide abstract] ABSTRACT: Anxiety-related behaviors increase histamine and dopamine release in the brain. On the other hand, central histamine counteracts reward and reinforcement processes mediated by the mesolimbic dopamine system. We investigated the effects of the histaminergic system and dopamine D2 receptors agents and their interactions on anxiety-related behaviors using the elevated plus-maze (EPM). The intra-hippocampal (Intra-CA1) microinjection of histamine (10μg/mouse) decreased the percentage of open arm time (%OAT) and open arm entries (%OAE) but not the locomotor activity, indicating an anxiogenic-like response. Quinpirole (0.5 and 2μg/mouse) or sulpiride (0.3 and 1μg/mouse) when injected into the dorsal hippocampus also induced anxiety-like behavior, however, the drugs reversed the anxiogenic response induced by the effective dose of histamine (10μg/mouse). Taken together and under the present experimental design, our results indicate that activation of the dorsal hippocampal histaminergic receptors causes anxiety-like behaviors altered by dopamine D2 receptor agonist and antagonist. Histamine can decrease dopaminergic tone in the dorsal hippocampus through decreasing the endogenous dopamine release, whereas quinpirole does the same via the postsynaptic DA receptors' activation. Sulpiride however renders the same effect through autoreceptors' blockade and potentiated dopamine transmission. Thus, quinpirole and sulpiride seem to compensate the effects of the intra-CA1 injection of exogenous histamine, and tend to exert anxiolytic effects in the presence of histamine.
[Show abstract][Hide abstract] ABSTRACT: BACKGROND: The amygdala is the key brain structure for anxiety and emotional memory storage. We examined the involvement of β-adrenoreceptors in the basolateral amygdala (BLA) and their interaction with morphine in modulating these behaviors.
The elevated plus-maze has been employed for investigating anxiety and memory. Male Wistar rats were used for this test. We injected morphine (4, 5, and 6 mg/kg) intraperitoneally, while salbutamol (albuterol) (1, 2, and 4 μg/rat) and propranolol (1, 2, and 4 μg/rat) were injected into the BLA. Open- arms time percentage (%OAT), open- arms entry percentage (%OAE), and locomotor activity were determined by this behavioral test. Retention was tested 24 hours later.
Intraperitoneal injection of morphine (6 mg/kg) had an anxiolytic-like effect and improvement of memory. The highest dose of salbutamol decreased the anxiety parameters in test session and improved the memory in retest session. Coadministration of salbutamol and ineffective dose of morphine presenting anxiolytic response. In this case, the memory was improved. Intra-BLA administration of propranolol (4 μg/rat) decreased %OAT in the test session, while had no effect on memory formation. Coadministration of propranolol and morphine (6 mg/kg) showed an increase in %OAT. There was not any significant change in the above- mentioned parameter in the retest session. Coadministration of morphine and propranolol with the effective dose of salbutamol showed that propranolol could reverse anxiolytic-like effect.
We found that opioidergic and β-adrenergic systems have the same effects on anxiety and memory in the BLA; but these effects are independent of each other.
Archives of Iranian medicine 05/2013; 16(5):281-7. · 1.11 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Background: Experimentally-induced total sleep deprivation (TSD) and chronic partial sleep restriction (CPSR) leads to the emergence of cognitive impairments. This is hypothesized to result from a consequent neuroinflammation which may also hasten the neurodegenerative processes. Neuroinflammatory markers such as tumor necrosis factor-alpha (TNFα) are thought to be potential culprits in SD-induced neurodegeneration. Methods: The effect of TSD and CPSR on memory and anxiety-related behaviors (using the Elevated Plus-Maze test-retest protocol) and serum level of brain derived neurotrophic factor (BDNF) and corticosterone were assessed in male Wistar rats subjected to the modified disk-over-water (DOW) apparatus. In addition, an immunohistochemical (IHC) study was done to possibly detect the amyloid-beta (Aβ) and hyper-phosphorylated tau protein (HPτ) deposition in the dentate gy-rus (DG) of the examined rats’ hippocampi. Histomorphology and neuronal numerical density assessments were done at the same level across control and experimental animals. We also studied the above parameters in rats after intraperitoneal injection of the TNFα neutralizing antibody, infliximab (IFX). Results: Rats subjected to TSD and CPSR which did not receive IFX, showed a more pronounced impairment of memory, elevated serum corticosterone and decreased BDNF levels. CPSR rats which underwent delayed brain excision following behav-ioral testing, showed deposition of the HPτ and revealed the least numerical density in the hippocampal DG neurons. Meanwhile, IHC study revealed no Aβ deposition in the hippo-campal DG of all examined rats. Interestingly, treatment with IFX, abrogated sleep re-striction-induced cognitive decline, biochemical changes and the immunohistopathology in the hippocampal DG. Conclusions: Taken together, our findings indicated that CPSR (the SD model mimicking shift work) induces not only cognitive and biochemical changes, but also pathology in the hippocampal DG. This is possibly via activation of the inflammatory mecha-nisms in part through TNFα-dependent pathways.
[Show abstract][Hide abstract] ABSTRACT: Bile duct ligation (BDL) is an animal model used in cholestatic disease research. Both opioidergic and nitrergic systems are known to be involved in cholestasis. The aim of this study was to investigate the possible interaction between these two systems in BDL-induced memory formation and exploratory behaviors in mice. Male mice weighing 25-30 g were divided into nonoperated controls, sham-operated, and BDL groups. One-trial step-down and hole-board paradigms were used to assess memory acquisition and exploratory behaviors, respectively. Cholestasis did not alter memory acquisition while increasing exploratory behaviors 7 days after BDL. A pretraining intraperitoneal injection of L-arginine (50, 100, and 200 mg/kg), L-NG-nitroarginine methyl ester (L-NAME) (5, 10, 20, and 40 mg/kg), or naloxone (0.125, 0.25, and 0.5 mg/kg) did not alter memory acquisition or exploratory behaviors, whereas morphine (5 and 7.5 mg/kg) decreased memory acquisition in sham-operated animals. Moreover, although injection of L-NAME and naloxone exerted no effect on memory acquisition in the 7 days post-BDL mice, L-arginine (100 and 200 mg/kg) and morphine (2.5, 5, and 7.5 mg/kg) injection reduced it. In contrast, L-NAME and naloxone, but not morphine or L-arginine, reduced the BDL-induced exploratory behaviors. Coadministration of subthreshold doses of morphine (1.25 mg/kg) and L-arginine (50 mg/kg) caused a memory deficit in 7 days post-BDL mice. However, the memory deficit induced by the effective doses of morphine (2.5 mg/kg) or L-arginine (200 mg/kg) in these mice was restored by the administration of either naloxone (0.5 mg/kg) or L-NAME (40 mg/kg). In addition, naloxone and L-NAME reduced the exploratory behaviors in L-arginine-pretreated mice but not in morphine-pretreated mice. We conclude that there appears to be a synergistic effect between opioidergic and nitrergic systems on memory acquisition and exploratory behaviors in cholestatic mice.
[Show abstract][Hide abstract] ABSTRACT: BACKGROUND: Nucleus accumbens (NAc) and prefrontal cortex (PFC) dopaminergic and glutamatergic systems are involved in fear/anxiety-related behaviors; meanwhile NAc dopaminergic system activity is mediated by PFC via NAc glutamatergic projections. This study has investigated the involvement of NAc shell dopaminergic system in prelimbic NMDA-induced anxiolytic-like behaviors. METHOD: elevated plus-maze apparatus was employed to test parameters of anxiety-like behaviors in male Wistar rats. RESULTS: unilateral intra-prelimbic injection of NMDA (0.9 μg/μl) but not D-AP7 (NMDA receptor antagonist; 0.25, 0.5 and 1 μg/μl) induced anxiolytic-like behaviors which was blocked by D-AP7. Moreover, unilateral infusion of SCH23390 (dopamine D1 receptor antagonist; 0.25, 0.5 and 1μg/μl) and quinpirole (dopamine D2 receptor agonist; 0.125, 0.25 and 0.5 μg/μl) into the left NAc shell, did not alter anxiety-like behaviors. However, injection of SKF38393 (dopamine D1 receptor agonist; 3 μg/μl) and sulpiride (dopamine D2 receptor antagonist; 0.4 and 0.6 μg/μl) into the left NAc shell, likewise induced anxiolytic-like behaviors which were blocked by SCH23390 (0.25μg/μl) and SKF96365 (Ca-channel blocker; 0.125 μg/μl)/SCH23390 (0.25 μg/μl), respectively. Furthermore, infusion of the subthreshold dose of SCH23390 (0.25 μg/μl) or quinpirole (0.25 μg/μl) into the left NAc shell, reduced while did not alter intra- prelimbic NMDA-induced anxiolytic-like behaviors, respectively. In addition, intra-NAc shell administration of the subthreshold dose of SKF38393 (1 μg/μl) or sulpiride (0.2 μg/μl), potentiated the lower dose response, while decreased the higher dose intra-left prelimbic NMDA response. CONCLUSION: our results suggested a modulatory effect of the NAc shell dopaminergic system on prelimbic NMDA-induced anxiolytic-like behaviors.
[Show abstract][Hide abstract] ABSTRACT: BACKGROUND AND AIM: Numerous investigations have indicated that hepatic encephalopathy (HE) alters the levels of various neurotransmitters. However, comprehensive data regarding the effects of CA1 opioidergic and dopaminergic (DAergic) systems on HE-induced amnesia are still lacking. METHODS: Following intra-dorsal hippocampal (CA1) injection of mu opioid and dopamine D1- and D2-like receptors antagonists in male mice, one-trial step-down and hole-board paradigms were used to assess memory and exploratory behaviors, respectively. RESULTS: Our data demonstrated that HE impairs memory 24 days after bile duct ligation (BDL). Furthermore, while the higher dose of DA D1-like receptor antagonist (SCH23390, 0.5 μg/mouse) induced amnesia and anxiogenic-like behaviors, mu receptor antagonist (naloxone: 0.0125, 0.025 and 0.05 μg/mouse) and DA D2-like receptor antagonist (sulpiride: 0.0625, 0.125 and 0.25 μg/mouse) by themselves, could not exert an effect on memory performance in passive avoidance task. On the other hand, pre-test injection of all drugs reversed the HE-induced amnesia 24 days after BDL, while having no effect on exploratory behaviors. Pre-test co-administration of the subthreshold dose SCH23390 (0.25 μg/mouse) and sulpiride (0.0625 μg/mouse) or naloxone (0.0125 μg/mouse) could likewise reverse the BDL-induced amnesia. However, when the subthreshold sulpiride plus naloxone were co-administered, BDL-induced amnesia was not blocked. CONCLUSIONS: Memory performance is impaired 24 days post BDL and CA1 mu opioid and DA D1-like receptors antagonist synergistic effects are likely involved in this phenomenon.
[Show abstract][Hide abstract] ABSTRACT: Dysfunctions in dopamine transmission system have been suggested to contribute to the pathogenesis of hepatic encephalopathy. In an experimental animal model, cholestasis induction through bile duct ligation may present several main pathological features of hepatic encephalopathy. Dopaminergic systems are shown to play pivotal roles in regulation of anxiety-like behaviors. The main bile duct in male Wistar rats, weighing 220-240g, was ligated using two ligatures plus duct transection in between. Anxiety-like behaviors were measured using the elevated plus maze task. Cholestasis increased the open arm time percentage (%OAT), 13 but not 10 days after bile duct ligation, indicating an anxiolytic-like effect. Sole intraperitoneal injection of apomorphine (dopamine D(1)/D(2) receptor agonist, 0.25mg/kg), SCH23390 (dopamine D(1) receptor antagonist, 0.005, 0.01 and 0.02mg/kg) or sulpiride (dopamine D(2) receptor antagonist, 0.125, 0.25 and 0.5mg/kg) did not alter %OAT, open arm entries percentage (%OAE) and locomotor activity in the sham-operated rats. Meanwhile, the higher dose apomorphine (0.5mg/kg) induced anxiolytic-like behaviors in this group. The subthreshold dose injection of SCH23390 or sulpiride, partially reversed the anxiolytic-like behaviors induced by cholestasis (13 days after bile duct ligation). On the other hand, subthreshold dose of apomorphine in cholestatic rats (10 days post bile duct ligation) induced anxiolytic-like effects which could be blocked by SCH23390 or sulpiride. The effective doses of above drugs did not alter locomotor activity, number of rearings, groomings and defections. These findings suggested that the dopaminergic system may potentially be involved in the modulation of cholestasis induced anxiolytic-like behaviors in rats.
European journal of pharmacology 01/2013; · 2.59 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The amnesic effect of morphine is well known in the laboratory animals. But, it is unclear that morphine at what times can exactly affect different phases of memory, including acquisition, consolidation, and retrieval. Therefore, we investigated the time profile of morphine's amnesic effect on passive (inhibitory) avoidance learning and memory in male Wistar rats.
In order to evaluate the outcomes of pre- and post-training administrations of morphine, the animals were trained in a step-through type of passive avoidance task at various time points, and were tested 24 h after training to measure memory retrieval.
The results showed that acquisition of memory was impaired in the animals that received a dose of 7.5 mg/kg of morphine (Intraperitoneally) at 0, 30 min, and 1 h before training, as evidenced by a decrease in step-through latency on the test day. Post-training administrations of morphine at 30 min and 1h, 4h except for the time immediately after training, did not impair memory consolidation. The results also showed that pre-test administrations of morphine at 0 and 30 min before the test, impaired retrieval of inhibitory avoidance memory.
Taken together, the results suggest that morphine, when injected at different time points before training, after training, or before testing affects different phases of inhibitory avoidance memory. With regard to the time of injections related to each phase, other experiments can be designed to investigate molecular mechanisms involved in the impairing effect of morphine in each phase.
Archives of Iranian medicine 01/2013; 16(1):34-7. · 1.11 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Benzodiazepines are useful drugs for treatment of sleep disorders, anxiety, seizure cases and skeletal muscle cramps. Some derivatives of 2-(2-Phenoxy) phenyl-1, 3, 4-oxadiazole were synthesized as benzodiazepine receptor agonists. Conformational analysis and superimposition of energy minima conformers of the compounds on estazolam, a known benzodiazepine agonist, reveal that the main proposed benzodiazepine pharmacophores were well matched. Anticonvulsant activity of the synthesized compounds, determined by pentylenetetrazole-induced lethal convulsion test, showed that the introduction of an amino substituent in position 5 of 1,3,4- oxadiazole ring generates compound 9 which has a respectable effect. The results are in agreement with SAR of benzodiazepine receptor ligands since the elimination of electronegative substituent in position 2 of phenoxy ring or position 4 of phenyl ring reduces the anticonvulsant activity.
Iranian journal of pharmaceutical research (IJPR) 01/2013; 12(Suppl):105-11. · 0.51 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The Cholinergic and GABAergic fibers of the medial septal/diagonal band of Broca (MS/ DB) area project to the hippocampus and constitute the septo-hippocampal pathway, which has been proven to play a role in learning and memory. In addition, the hippocampus has bidirectional connections with the septum so that to self-regulate of cholinergic input. The activity of septal and hippocampal neurons is modulated by several neurotransmitter systems including glutamatergic neurons from the entorhinal cortex, serotonergic fibers from the raphe nucleus, dopaminergic neurons from the ventral tegmental area (VTA), histaminergic cells from the tuberomammillary nucleus and adrenergic fibers from the locus coeruleus (LC). Thus, changes in the glutamatergic, serotonergic and other systems-mediated transmission in the MS/DB may influence cholinergic or GABAergic transmission in the hippocampus.
[Show abstract][Hide abstract] ABSTRACT: RATIONALE: Cannabinoids are shown to modulate the hippocampal memory processing through different neuronal systems such as GABAergic and glutamatergic. This study investigates the effects of dorsal hippocampal (CA1) GABA(A) receptors on spatial and non-spatial novelty detection deficit, induced by a selective CB1 receptor agonist (ACPA), during a non-associative task. METHODS: Male mice weighing 30-35 g were used. Open field paradigm was employed to assess the spatial and non-spatial memory retention. RESULTS: Our data showed that intraperitoneal injection of the higher doses of ACPA (0.005, 0.01 and 0.02 mg/kg) decreases spatial change detection as well as the reaction to non-spatial novelty. Moreover, isolated intra-CA1 injection of bicuculline (GABA(A) receptor antagonist) at 0.0625, 0.125 and 0.25 μg/mouse did not alter the spatial change detection and non-spatial novelty in saline treated mice. On the other hand, intra-CA1 injection of the higher doses of muscimol (GABA(A) receptor agonist) at 0.25, 0.5 and 1 μg/mouse, not only impaired the spatial change detection on its own, but also affected the reaction to non-spatial novelty. In addition, the subthreshold dose of bicuculline reversed the impaired spatial and non-spatial memory in mice which received post-training injection of ACPA effective dose (0.02 mg/kg). Meanwhile, co-administration of the subthreshold and effective doses of muscimol and ACPA (0.005 mg/kg) could only impair the spatial change detection ability but not the reaction to non-spatial novelty. CONCLUSION: Our results suggested that the ACPA induced impairment of memory retention, may occur through dorsal hippocampal (CA1) GABA(A) receptors thus, blockade of these receptors can possibly reverse this phenomenon.
Neurobiology of Learning and Memory 12/2012; · 4.04 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: This study was designed to investigate the involvement of β-adrenoceptors of the dorsal hippocampus (DH) in ethanol-induced state-dependent retrieval. We used a step-down type of inhibitory avoidance (IA) task to assess retrieval in male NMRI mice. Bilateral guide cannulae were implanted in the DH. The results showed that in the animals with pre-training injections of ethanol (1g/kg, i.p.) and pre-test saline treatment memory retrieval was impaired. Pre-test injections of ethanol (0.5 and 1g/kg, i.p.) also impaired memory retrieval in the animals that received saline before training. Ethanol (1 g/kg, i.p.), when injected in both time points of pre-training and pre-test, induced state-dependent retrieval. The results also revealed that intra- DH infusions of a β-adrenoceptor agonist salbutamol (0, 0.0025, 0.005, 0.01 and 0.02 μg/mouse) by itself had no significant effect, however, along with an ineffective dose of ethanol (0.25 g/kg) significantly improved memory retrieval. On the other hand, pre-test intra-DH infusions of different doses of a non-selective β-adrenoceptor antagonist propranolol (0, 0.1, 0.3 and 0.5μg/mouse) by itself had no effect on memory retrieval. But, pre-test intra-DH infusions of the same doses of propranolol (0, 0.1, 0.3 and 0.5μg/mouse) disrupted ethanol-induced state-dependent retrieval. Interestingly, intra-DH infusions of propranolol (0.05, 0.75 and 0.1 μg/mouse) inhibited the improving effect of salbutamol on state-dependent retrieval. In conclusion, the results support the existence of a functional involvement of β-adrenoceptors in the DH in ethanol-induced state-dependent retrieval.
Neurobiology of Learning and Memory 12/2012; · 4.04 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Nicotine, the major addictive substance in tobacco, increases the activity of the central amygdala (CeA). Amygdala is directly implicated in anxiety modulation and sends projections to the vicinity of midbrain dopamine neurons, including the ventral tegmental area (VTA) which is key area that controls nicotine dependence processes. In this study, the role of dopamine D(1) and D(2)/(3) receptors of the VTA on anxiogenic-like behavior induced with intra-CeA injection of nicotine has been investigated. Male Wistar rats with cannula aimed to the left CeA and the left VTA were submitted to the elevated plus-maze (EPM). The nicotine injection (1μg/rat) into the CeA decreased the percentage of open arm time and open arm entries, but not locomotor activity, indicating an anxiogenic-like response. Intra-VTA injection of a dopamine D1 receptor antagonist, SCH23390 (0.25μg/rat), and a dopamine D2/3 receptor antagonist, sulpiride (0.7μg/rat), inhibited the anxiogenic-like response caused by intra-CeA injection of nicotine. These results suggest that relationship between the VTA and the CeA may be involved in nicotine-induced anxiogenic-like behavior via dopamine D(1) and D(2)/(3) receptors. An understanding of these cellular processes will be crucial for the development of new intervention to combat nicotine effect.
Progress in Neuro-Psychopharmacology and Biological Psychiatry 11/2012; · 4.03 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Harmane (HA) is a β-carboline alkaloid derived from the Peganum harmala plant which induces memory impairment. On the other hand some of investigations showed that β-carboline alkaloids inhibit NO production. Thus, the aim of the present study was to investigate the role of nitrergic system of the dorsal hippocampus (CA1) in HA-induced amnesia in male adult mice. One-trial step-down passive avoidance and hole-board apparatuses were used for the assessment of memory retrieval and exploratory behaviors respectively. The data indicated that pre-training intraperitoneal (i.p.) administration of HA (12 and 16mg/kg) decreased memory acquisition. Sole pre-training or pre-testing administration of L-NAME, a nitric oxide synthesis inhibitor (5, 10 and 15μg/mice, intra-CA1) did not alter memory retrieval. On the other hand, pre-training (10 and 15μg/mice, intra-CA1) and pre-testing (5, 10μg/mice, intra-CA1) injections of L-NAME restored HA-induced amnesia (16mg/kg, i.p.). Furthermore, neither sole pre-training nor pre-testing administration of L-arginine, a NO precursor (3, 6 and 9μg/mice, intra-CA1), altered memory retrieval. In addition, pre-testing (6 and 9μg/mice, intra-CA1), but not pre-training, injection of L-arginine increased HA-induced amnesia (16mg/kg, i.p.). These results suggest that the nitrergic system of CA1 is involved in HA-induced amnesia.
[Show abstract][Hide abstract] ABSTRACT: Several investigations have indicated that cholestasis decreases opioid receptor expression in the brain following increased opioidergic neurotransmission. The opioidergic system plays an important role in regulation of reward circuits that may be produced via dopamine-dependent mechanisms. It has been suggested that the dopaminergic system of the nucleus accumbens is necessary in conditioned place preference (CPP). The aim of this study is, therefore, to test if cholestasis can alter the reward system and the involvement of opioidergic and dopaminergic systems in this phenomenon.
We used CPP and hole-board paradigms to measure the reward effect and exploratory behaviors, respectively, in mice. Cholestasis was induced by ligation of the main bile duct, using two ligatures and transecting the duct between them (BDL mice).
The data showed that morphine (1 and 2 mg/kg), sulpiride (80 mg/kg) and SKF38393 (20 mg/kg) produced CPP, while naloxone (1 mg/kg) and SCH23390 (1mg/kg) produced conditioned place aversion (CPA), whereas quinpirole had no effect in sham-operated mice. However, morphine (2 mg/kg, i.p.), sulpiride (40 mg/kg) and? SKF38393 (10 mg/kg) induced CPP in BDL mice compared to sham-operated mice. Naloxone- or SCH23390-induced CPA was reduced in BDL mice compared with the respective sham-operated mice. Quinpirole tended to induce aversion in BDL mice which was, however, not significant. In addition, quinpirole 1 mg/kg) and SCH23390 (1 mg/kg) increased head-dip exploratory behavior, whereas naloxone (2 mg/kg) caused a decrease in head-dip exploratory behavior in sham-operated mice. Morphine (2 mg/kg), SCH23390 (1 mg/kg) and quinpirole (0.25 and 0.5 mg/kg) induced anxiogenic-like behavior in BDL mice.
It can be concluded that cholestasis differentially alters the reward effects of opioidergic and dopaminergic agents.
Archives of Iranian medicine 10/2012; 15(10):617-24. · 1.11 Impact Factor