[show abstract][hide abstract] ABSTRACT: Autophagy is an evolutionary conserved mechanism that allows for the degradation of long-lived proteins and entire organelles which are driven to lysosomes for digestion. Different kinds of stressful conditions such as starvation are able to induce autophagy. Lithium and rapamycin are potent autophagy inducers with different molecular targets. Lithium stimulates autophagy by decreasing the intracellular myo-inositol-1,4,5-triphosphate levels, while rapamycin acts through the inhibition of the mammalian target of rapamycin (mTOR). The correlation between autophagy and cell death is still a matter of debate especially in transformed cells. In fact, the execution of autophagy can protect cells from death by promptly removing damaged organelles such as mitochondria. Nevertheless, an excessive use of the autophagic machinery can drive cells to death via a sort of self-cannibalism. Our data show that lithium (used within its therapeutic window) stimulates the overgrowth of the rat Pheochromocytoma cell line PC12. Besides, lithium and rapamycin protect PC12 cells from toxic compounds such as thapsigargin and trimethyltin. Taken together these data indicate that pharmacological activation of autophagy allows for the survival of Pheochromocytoma cells in stressful conditions such as high-density cultures and exposure to toxins.
International Journal of Cell Biology 01/2014; 2014:135908.
[show abstract][hide abstract] ABSTRACT: In the present study we investigated the effect of two different exercise protocols on fibre composition and metabolism of two specific muscles of mice: the quadriceps and the gastrocnemius. Mice were run daily on a motorized treadmill, at a velocity corresponding to 60% or 90% of the maximal running velocity. Blood lactate and body weight were measured during exercise training. We found that at the end of training the body weight significantly increased in high-intensity exercise mice compared to the control group (P=0.0268), whereas it decreased in low-intensity exercise mice compared to controls (P=0.30). In contrast, the food intake was greater in both trained mice compared to controls (P<0.0001 and P<0.0001 for low-intensity and high-intensity exercise mice, respectively). These effects were accompanied by a progressive reduction in blood lactate levels at the end of training in both the exercised mice compared with controls (P=0.03 and P<0.0001 for low-intensity and high-intensity exercise mice, respectively); in particular, blood lactate levels after high-intensity exercise were significantly lower than those measured in low-intensity exercise mice (P=0.0044). Immunoblotting analysis demonstrated that high-intensity exercise training produced a significant increase in the expression of mitochondrial enzymes contained within gastrocnemius and quadriceps muscles. These changes were associated with an increase in the amount of slow fibres in both these muscles of high-intensity exercise mice, as revealed by the counts of slow fibres stained with specific antibodies (P<0.0001 for the gastrocnemius; P=0.0002 for the quadriceps). Our results demonstrate that high-intensity exercise, in addition to metabolic changes consisting of a decrease in blood lactate and body weight, induces an increase in the mitochondrial enzymes and slow fibres in different skeletal muscles of mice, which indicates an exercise-induced increase in the aerobic metabolism.
Biology of Sport 12/2013; 30(4):301-309. · 0.42 Impact Factor
[show abstract][hide abstract] ABSTRACT: Formation, aggregation and transmission of abnormal proteins are common features in neurodegenerative disorders including Parkinson's disease, Alzheimer's disease, amyotrophic lateral sclerosis, and Huntington's disease. The mechanisms underlying protein alterations in neurodegenerative diseases remain controversial. Novel findings highlighted altered protein clearing systems as common biochemical pathways which generate protein misfolding, which in turn causes protein aggregation and protein spreading. In fact, proteinaceous aggregates are prone to cell-to-cell propagation. This is reminiscent of what happens in prion disorders, where the prion protein misfolds thus forming aggregates which spread to neighbouring cells. For this reason, the term prionoids is currently used to emphasize how several misfolded proteins are transmitted in neurodegenerative diseases following this prion-like pattern. Histochemical techniques including the use of specific antibodies covering both light and electron microscopy offer a powerful tool to describe these phenomena and investigate specific molecular steps. These include: prion like protein alterations; glycation of prion-like altered proteins to form advanced glycation end-products (AGEs); mechanisms of extracellular secretion; interaction of AGEs with specific receptors placed on neighbouring cells (RAGEs). The present manuscript comments on these phenomena aimed to provide a consistent scenario of the available histochemical approaches to dissect each specific step.
European journal of histochemistry: EJH 01/2013; 57(1):e5. · 2.41 Impact Factor
[show abstract][hide abstract] ABSTRACT: Mutations in the PTEN-induced putative kinase1 (PINK1) represent the second most frequent cause of autosomal recessive Parkinson's disease. The PINK1 protein mainly localizes to mitochondria and interacts with a variety of proteins, including the pro-autophagy protein beclin1 and the ubiquitin-ligase parkin. Upon stress conditions, PINK1 is known to recruit parkin at the surface of dysfunctional mitochondria and to activate the mitophagy cascade. Aim of this study was to use a simple and highly reproducible catecholamine cell model and transmission electron microscopy to characterize whether PINK1 could affect mitochondrial homeostasis, the recruitment of specific proteins at mitochondria, mitophagy and apoptosis. Samples were analyzed both in baseline conditions and following treatment with methamphetamine (METH), a neurotoxic compound which strongly activates autophagy and produces mitochondrial damage. Our data provide robust sub-cellular evidence that the modulation of PINK1 levels dramatically affects the morphology and number of mitochondria and the amount of cell death. In particular, especially upon METH exposure, PINK1 is able to increase the total number of mitochondria, concurrently recruit beclin1, parkin and ubiquitin and enhance the clearance of damaged mitochondria. In the absence of functional PINK1 and upon autophagy stress, we observe a failure of the autophagy system at large, with marked accumulation of dysfunctional mitochondria and dramatic increase of apoptotic cell death. These findings highlight the strong neuroprotective role of PINK1 as a key protein in the surveillance and regulation of mitochondrial homeostasis.
Archives italiennes de biologie 06/2012; 150(2-3):194-217. · 1.43 Impact Factor
[show abstract][hide abstract] ABSTRACT: The effects of training are dependent on complex, adaptive changes which are induced by acute physical exercise at different levels. In particular, evidence shows that the hypothalamus-pituitary-adrenocortical axis, as well as the sympatho-adrenomedullary system, is mainly involved in mediating the physiological effects of physical exercise. The aim of the present study was to investigate, through a morphological and biochemical approach, the effects of training on the adrenal gland of mice, following two different protocols consisting of either low- or high-intensity training. Mice were run daily on a motorised treadmill for 8 weeks, at a velocity corresponding to 60% (low-intensity exercise) or 90% (high-intensity exercise) of the maximal running velocity previously determined by an incremental exercise test. We found that physical exercise produced an increase in the adrenal gland size compared with the control (sedentary) mice. The increase was 31.04% for mice that underwent high-intensity exercise and 10.08% for mice that underwent low intensity exercise, and this appeared to be the result of an increase in the area of both the adrenal cortex and adrenal medulla. Morphological analysis of the adrenal cortex showed that both types of exercise produced an increase in cytoplasmic vacuoles in steroidogenic cells, appearing more abundant after high-intensity exercise. No change was found in the reticulate zone. In the adrenal medulla, despite the absence of morphological changes, immunohistochemistry for tyrosine hydroxylase, dopamine β-hydroxylase and phenyl-ethanolamine-N-methyltransferase demonstrated an increased immunopositivity for these cathecolamine-synthesizing enzymes after intense exercise. These results were confirmed by immunoblot accompanied by densitometric analysis.
Histology and histopathology 06/2012; 27(6):753-69. · 2.28 Impact Factor
[show abstract][hide abstract] ABSTRACT: Capecitabine plus oxaliplatin combination (XELOX) is the first-line treatment in metastatic colorectal cancer. Here we report a case of acute, severe but substantially reversible, neuromuscular and cardiac toxicity following XELOX chemotherapy. Muscle biopsy findings were consistent with a toxic myopathy with necrotizing features and vacuolar changes; COX-negative fibers were also present. The time course could support a main role for capecitabine, which may have some neurotoxic effects (more frequently central), but a detrimental interaction between the two drugs cannot be ruled out and further studies are needed.
[show abstract][hide abstract] ABSTRACT: Trimethyltin (TMT) is a triorganotin compound which determines neurodegeneration of specific brain areas particularly damaging the limbic system. Earlier ultrastructural studies indicated the formation of autophagic vacuoles in neurons after TMT intoxication. However, no evaluation has been attempted to determine the role of the autophagic pathway in TMT neurotoxicity. To assess the contribution of autophagy to TMT-induced neuronal cell death, we checked the vulnerability of neuronal cultures to TMT after activation or inhibition of autophagy. Our results show that autophagy inhibitors (3-methyladenine and L-asparagine) greatly enhanced TMT neurotoxicity. Conversely, known activators of autophagy, such as lithium and rapamycin, displayed neuroprotection against this toxic compound. Due to its diverse targets, the action of lithium was complex. When lithium was administered according to a chronic treatment protocol (6 days pretreatment) it was able to rescue both hippocampal and cortical neurons from TMT (or from glutamate toxicity used as reference). This effect was accompanied by an increased phosphorylation of glycogen synthase kinase 3 which is a known target for lithium neuroprotection. If the pre-incubation time was reduced to 2 h (acute treatment protocol), lithium was still able to counteract TMT toxicity in hippocampal but not in cortical neurons. The neuroprotective effect of lithium acutely administered against TMT in hippocampal neurons can be completely reverted by an excess of inositol and is possibly related to the inactivation of inositol monophosphatase, a key regulator of autophagy. These data indicate that TMT neurotoxicity can be dramatically modified, at least in vitro, by lithium addition which seems to act through different mechanisms if acutely or chronically administered.
Journal of Neural Transmission 03/2012; 119(11):1295-305. · 3.05 Impact Factor
[show abstract][hide abstract] ABSTRACT: We investigated the genotype-dependency of morphological abnormalities in peripheral cells from Huntington disease (HD) patients. Cell cultures derived from skin and muscle biopsies showed a different set of abnormalities depending on the genotype (i.e. heterozygous and homozygous for CAG mutations) and the tissue (i.e. fibroblasts and myoblasts). In general, homozygotes' cell lines showed massive ultrastructural damage of specific cell organelles compared with age matched control. These consist of vacuolization, deranged crests and matrix found within giant mitochondria. In addition, enlarged endoplasmic reticulum and the occurrence of numerous autophagic vacuoles, which were similar to those occurring in neurons within affected brain areas, were described. Despite a comparable dose-dependency on mitochondrial changes, this kind of alterations differ in fibroblasts compared with myoblasts. In fact, the internal mitochondrial structure was merely lost in myoblasts, while it shows pathological re-organization within fibroblasts, where altered crests appear as multilamellar circles. These data indicate that ultrastructural abnormalities from peripheral tissues of HD patients can be used as potential disease markers which are easier to get than autoptic brains. Moreover, the occurrence of ultrastructural cell pathology reminiscent of neuronal degeneration in HD, suggests the use of human peripheral cells as a tool to investigate the pathogenic cascade subsequent to huntingtin dysregulation.
Journal of Neural Transmission 10/2009; 117(1):77-83. · 3.05 Impact Factor
[show abstract][hide abstract] ABSTRACT: A variety of neurodegenerative diseases leading to movement disorders such as Parkinson's disease (PD) are characterized by neuronal inclusions. Despite evidence of the presence of these intrusions, these intracellular bodies have been poorly investigated because of the technical limits of reproducing them in experimental models and the difficulties in isolating these ultrastuctures. Here, we describe a simple method for the isolation of single, purified inclusion bodies using immunomagnetic separation. We profited from the high number and maturation stage of inclusions produced in vitro by methamphetamine (METH) in cultured PC12 cells; in fact, this experimental condition is highly reproducible and has a limited number of experimental variables, while it is predictive of what is described in vivo in dopamine neurons.
Annals of the New York Academy of Sciences 11/2008; 1139:186-90. · 4.38 Impact Factor
[show abstract][hide abstract] ABSTRACT: Dopamine (DA) axons in the developing striatum cluster in discrete areas called "DA islands". During the third postnatal week, most DA islands are no-longer detectable and the DA innervation becomes uniform. In this study we explored the relationship between the pattern of DA innervation and the number of striatal tyrosine hydroxylase positive (TH+) cells during early postnatal development. By using dedicated stereology we found that the newborn striatum contains striatal TH+ cells, which cluster around newly sprouted DA axons. The number of these cells decreases when DA axons develop a full pattern of striatal innervation. This condition suggests a causal relationship between the amount of striatal DA innervation and the presence of striatal DA neurons. A better knowledge of the mechanisms regulating the ontogenesis of the nigrostriatal DA system may pave the way to strategies of neurorescue of the DA system.
Journal of Neural Transmission 09/2008; 115(10):1375-83. · 3.05 Impact Factor
[show abstract][hide abstract] ABSTRACT: Exposure of PC12 cells to metamphetamine (MA) induces the formation of multilamellar structures (whorls) resembling autophagic granules that subsequently develop as intracellular inclusions. These inclusions stain for a variety of antigens belonging to the ubiquitin proteasome pathway. Since MA-induced intracellular bodies require the presence of dopamine in the present study we analyzed the role of dopamine (DA) receptors in producing neuronal inclusions. Moreover, we investigated potential signaling pathways which could lead to ubiquitination in the presence of MA. Based on recent reports that ubiquitination of beta-adrenergic receptors is promoted by beta-arrestin which shuttles proteins from the plasma membrane to the ubiquitin proteasome system we investigated whether beta-arrestin is involved in MA-induced inclusion formation. Our experiments document that (i) beta-arrestin was associated with MA-induced intracellular bodies; (ii) MA induced a rapid and reversible ubiquitination of beta-arrestin; (iii) dopamine antagonists reduced both MA-induced beta-arrestin ubiquitination and intracellular whorls formation; (iv) the number of MA-induced intracellular bodies was reduced in cells transfected with the beta-arrestin dominant negative mutant, betaarrV53D and was increased by the persistently ubiquitinated beta-arrestin-ubiquitin fusion protein. In conclusion, the present study demonstrates the involvement of beta-arrestin in MA-induced intracellular bodies and the participation of dopamine receptors in this process.
Journal of Neurochemistry 07/2008; 105(5):1939-47. · 3.97 Impact Factor
[show abstract][hide abstract] ABSTRACT: Methamphetamine abuse is toxic to dopaminergic neurons, causing nigrostriatal denervation and striatal dopamine loss. Following methamphetamine exposure, the number of nigral cell bodies is generally preserved, but their cytoplasm features autophagic-like vacuolization and cytoplasmic accumulation of alpha-synuclein-, ubiquitin- and parkin-positive inclusion-like bodies. Whether autophagy is epiphenomenal or it plays a role in the mechanism of methamphetamine toxicity and, in the latter case, whether its role consists of counteracting or promoting the neurotoxic effect remains obscure. We investigated the signaling pathway and the significance (protective vs. toxic) of autophagy activation and the convergence of the autophagic and the ubiquitin-proteasome pathways at the level of the same intracellular bodies in a simple cell model of methamphetamine toxicity. We show that autophagy is rapidly up-regulated in response to methamphetamine. Confocal fluorescence microscopy and immuno-electron microscopy studies demonstrated the presence of alpha-synuclein aggregates in autophagy-lysosomal structures in cells exposed to methamphetamine, a condition compatible with cell survival. Inhibition of autophagy either by pharmacologic or genetic manipulation of the class III Phosphatidylinositol-3 kinase-mediated signaling prevented the removal of alpha-synuclein aggregates and precipitated a bax-mediated mitochondrial apoptosis pathway.
Journal of Neurochemistry 07/2008; 106(3):1426-39. · 3.97 Impact Factor
[show abstract][hide abstract] ABSTRACT: N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP-4) lesions of the locus coeruleus, the major brain noradrenergic nucleus, exacerbate the damage to nigrostriatal dopamine (DA) terminals caused by the psychostimulant methamphetamine (METH). However, because noradrenergic terminals contain other neuromodulators and the noradrenaline (NA) transporter, which may act as a neuroprotective buffer, it was unclear whether this enhancement of METH neurotoxicity was caused by the loss of noradrenergic innervation or the loss of NA itself. We addressed the specific role of NA by comparing the effects of METH in mice with noradrenergic lesions (DSP-4) and those with intact noradrenergic terminals but specifically lacking NA (genetic or acute pharmacological blockade of the NA biosynthetic enzyme dopamine beta-hydroxylase; DBH). We found that genetic deletion of DBH (DBH-/- mice) and acute treatment of wild-type mice with a DBH inhibitor (fusaric acid) recapitulated the effects of DSP-4 lesions on METH responses. All three methods of NA depletion enhanced striatal DA release, extracellular oxidative stress (as measured by in vivo microdialysis of DA and 2,3-dihydroxybenzoic acid), and behavioral stereotypies following repeated METH administration. These effects accompanied a worsening of the striatal DA neuron terminal damage and ultrastructural changes to medium spiny neurons. We conclude that NA itself is neuroprotective and plays a fundamental role in the sensitivity of striatal DA terminals to the neurochemical, behavioral, and neurotoxic effects of METH.
Journal of Neurochemistry 05/2008; 105(2):471-83. · 3.97 Impact Factor
[show abstract][hide abstract] ABSTRACT: ALS is a devastating neurodegenerative disorder with no effective treatment. In the present study, we found that daily doses of lithium, leading to plasma levels ranging from 0.4 to 0.8 mEq/liter, delay disease progression in human patients affected by ALS. None of the patients treated with lithium died during the 15 months of the follow-up, and disease progression was markedly attenuated when compared with age-, disease duration-, and sex-matched control patients treated with riluzole for the same amount of time. In a parallel study on a genetic ALS animal model, the G93A mouse, we found a marked neuroprotection by lithium, which delayed disease onset and duration and augmented the life span. These effects were concomitant with activation of autophagy and an increase in the number of the mitochondria in motor neurons and suppressed reactive astrogliosis. Again, lithium reduced the slow necrosis characterized by mitochondrial vacuolization and increased the number of neurons counted in lamina VII that were severely affected in saline-treated G93A mice. After lithium administration in G93A mice, the number of these neurons was higher even when compared with saline-treated WT. All these mechanisms may contribute to the effects of lithium, and these results offer a promising perspective for the treatment of human patients affected by ALS.
Proceedings of the National Academy of Sciences 03/2008; 105(6):2052-7. · 9.74 Impact Factor
[show abstract][hide abstract] ABSTRACT: In a pilot clinical study that we recently published we found that lithium administration slows the progression of Amyotrophic Lateral Sclerosis (ALS) in human patients. This clinical study was published in addition with basic (in vitro) and pre-clinical (in vivo) data demonstrating a defect of autophagy as a final common pathway in the genesis of ALS. In fact, lithium was used as an autophagy inducer. In detailing the protective effects of lithium we found for the first time that this drug stimulates the biogenesis of mitochondria in the central nervous system and, uniquely in the spinal cord, it induces neuronogenesis and neuronal differentiation. In particular, the effects induced by lithium can be summarized as follows: (i) the removal of altered mitochondria and protein aggre-gates; (ii) the biogenesis of well-structured mitochondria; (iii) the suppression of glial proliferation; (iv) the differentiation of newly formed neurons in the spinal cord towards a specific phenotype. In this addendum we focus on defective autophagy as a "leit motif " in ALS and the old and novel features of lithium which bridge autophagy activation to concomitant effects that may be useful for the treatment of a variety of neurodegenerative disor-ders. In particular, the biogenesis of mitochondria and the increase of calbindin D 28K-positive neurons, which are likely to support powerful neuroprotection towards autophagy failure, mitochondri-opathy and neuronal loss in the spinal cord. Amyotrophic Lateral Sclerosis (ALS) is an adult-onset devastating neurodegenerative disease. The pathological hallmark of ALS is the progressive atrophy and final death of motor neurons (MN), preceded by swelling of perikarya and proximal axons, and accu-mulation of Bunina bodies (small cystatin C-containing neuronal inclusions and Lewy body-like inclusions). In addition activation and proliferation of astrocytes and microglia and the depositions of inclusions and ubiquitinated material are also common. 1 In the study we recently published 2 we found that lithium administration slowed down the progression of ALS in a small group of patients. Lithium is a well known mood-stabilizing drug used for the treatment of bipolar affective disorders. At the same time, lithium is increasingly recognized as neuroprotectant. 2-5 In fact, lithium has been shown to protect neurons from β-amyloid-induced degeneration associated with Alzheimer's disease, 6-8 to protect hyppocampal neurons from brain ischemia 5 and kainate-induced seizure and brain damage 4 . At the same time, lithium is shown to be an autophagy inducer 9,10 leading to upregulation of the autophagy-lysosomal degradative pathway. 9 Lithium, Autophagy and ALS
[show abstract][hide abstract] ABSTRACT: In a pilot clinical study that we recently published we found that lithium administration slows the progression of Amyotrophic Lateral Sclerosis (ALS) in human patients. This clinical study was published in addition with basic (in vitro) and pre-clinical (in vivo) data demonstrating a defect of autophagy as a final common pathway in the genesis of ALS. In fact, lithium was used as an autophagy inducer. In detailing the protective effects of lithium we found for the first time that this drug stimulates the biogenesis of mitochondria in the central nervous system and, uniquely in the spinal cord, it induces neuronogenesis and neuronal differentiation. In particular, the effects induced by lithium can be summarized as follows: (i) the removal of altered mitochondria and protein aggregates; (ii) the biogenesis of well-structured mitochondria; (iii) the suppression of glial proliferation; (iv) the differentiation of newly formed neurons in the spinal cord towards a specific phenotype. In this addendum we focus on defective autophagy as a "leit motif" in ALS and the old and novel features of lithium which bridge autophagy activation to concomitant effects that may be useful for the treatment of a variety of neurodegenerative disorders. In particular, the biogenesis of mitochondria and the increase of calbindin D 28K-positive neurons, which are likely to support powerful neuroprotection towards autophagy failure, mitochondriopathy and neuronal loss in the spinal cord.
[show abstract][hide abstract] ABSTRACT: Recent studies demonstrated that methamphetamine (METH) produces intracellular bodies which are reminiscent of those occurring during degenerative disorders. In vivo studies demonstrate the occurrence of these morphological alterations both in the dopamine (DA) neurons of the substantia nigra and striatal cells. These consist of neuronal bodies staining for a variety of antigens belonging to the ubiquitin-proteasome pathway. The formation of these intracellular bodies both in the substantia nigra and PC12 cells depends on the presence of endogenous DA. In the present study, we analyze the mechanisms which lead to METH-induced intracellular bodies within non-dopaminergic striatal neurons. We found that METH is no longer able to produce inclusions in vivo, in striatal cells, when striatal DA is lost. Similarly, in vitro, in primary striatal cell cultures which do not possess DA, METH administration does not produce inclusions. On the other hand, administration of DA to striatal cell cultures produces neuronal inclusions and cell death, which are both related to the inhibition of the ubiquitin-proteasome system and activation of specific-DA receptors. In line with this, we produced subcellular alterations by administering dopamine agonists.
Journal of Neurochemistry 07/2007; 101(5):1414-27. · 3.97 Impact Factor
[show abstract][hide abstract] ABSTRACT: The PC12 cell line is commonly used as a tool to understand the biochemical mechanisms underlying the physiology and degeneration of central dopamine neurons. Despite the broad use of this cell line, there are a number of points differing between PC12 cells and dopamine neurons in vivo which are missed out when translating in vitro data into in vivo systems. This led us to compare the PC12 cells with central dopamine neurons, aiming at those features which are predictors of in vivo physiology and degeneration of central dopamine neurons. We carried out this comparison, either in baseline conditions, following releasing or neurotoxic stimuli (i.e. acute or chronic methamphetamine), to end up with therapeutic agents which are suspected to produce neurotoxicity (l-DOPA). Although the neurotransmitter pattern of PC12 cells is close to dopamine neurons, ultrastructural morphometry demonstrates that, in baseline conditions, PC12 cells possess very low vesicles density, which parallels low catecholamine levels. Again, compartmentalization of secretory elements in PC12 cells is already pronounced in baseline conditions, while it is only slightly affected following catecholamine-releasing stimuli. This low flexibility is caused by the low ability of PC12 cells to compensate for sustained catecholamine release, due both to non-sufficient dopamine synthesis and poor dopamine storage mechanisms. This contrasts markedly with dopamine-containing neurons in vivo lending substance to opposite findings between these compartments concerning the sensitivity to a number of neurotoxins.
Brain Research 02/2007; 1129(1):174-90. · 2.88 Impact Factor
[show abstract][hide abstract] ABSTRACT: The 6-hydroxydopamine (6-OHDA) model of Parkinson's disease in the rat represents a fundamental tool for investigating the pathophysiology of dopamine denervation. Nevertheless, 6-OHDA can induce also noradrenergic lesions; therefore desmethylimipramine (DMI) is co-administrated as a selective inhibitor of noradrenergic reuptake to protect noradrenaline (NA) fibers neighboring DA neurons and/or axons. The neurotoxin 6-OHDA must be microinfused selectively into the substantia nigra pars compacta (SNpc) or into the medial forebrain bundle (MFB) to determine the nigrostriatal lesion. However, this experimental procedure is invasive and always produces a certain amount of mechanical damage that cannot be prevented by pharmacological approaches. For this reason, we have compared two types of experimental design in which we tested critical steps of the procedures, such as the flow rate. We microinfused rats in MFB with 8 μL of total volume of a solution containing the neurotoxin (infusion rate 2 μL/min in 4 min) according with general practice, and rats microinfused with an amount of 2μL of total volume with a slower rate (0.2 μL/min in 10 min) of infusion. Rats infused with a higher flow rate of infusion underwent striatal NA loss in spite of the administration of DMI. On the contrary, rats infused with a slow infusion flow rate had spared NA axons following DMI. These results suggest that the flow rate and the volume of 6-OHDA infusion are critical to prevent the occurrence of nonspecific mechanical effects.
Annals of the New York Academy of Sciences 09/2006; 1074(1):344 - 348. · 4.38 Impact Factor