Selective vulnerability of cerebellar granule neuroblasts and their progeny to drugs with abuse liability

Allosteric modulation of α1β3γ2 GABAA receptors by farnesol through the neurosteroid sites

In mammalian cells, all-trans farnesol, a 15-carbon isoprenol, is a product of the mevalonate pathway. It is the natural substrate of alcohol dehydrogenase and a substrate for CYP2E1, two enzymes implicated in ethanol metabolism. Studies have shown that farnesol is present in the human brain and inhibits voltage-gated Ca2+ channels at much lower concentrations than ethanol. Here we show that farnesol modulates the activity of γ-aminobutyric acid type A receptors (GABAARs), some of which also mediate the sedative activity of ethanol. Electrophysiology experiments performed in HEK cells expressing human α1β3γ2 or α6β3γ2 GABAARs revealed that farnesol increased chloride currents through positive allosteric modulation of these receptors and showed dependence on both the alcoholic functional group of farnesol and the length of the alkyl chain for activity. In silico studies using long-timescale unbiased all-atom molecular dynamics (MD) simulations of the human α1β3γ2 GABAA receptors revealed that farnesol modulates the channel by directly binding to the transmembrane neurosteroid-binding site, after partitioning into the surrounding membrane and reaching the receptor by lateral diffusion. Channel activation by farnesol was further characterized by several structural and dynamic variables, such as global twisting of the receptor's extracellular domain, tilting of the transmembrane M2 helices, radius, cross-sectional area, hydration status, and electrostatic potential of the channel pore. Our results expand the pharmacological activities of farnesol to yet another class of ion channels implicated in neurotransmission, thus providing a novel path for understanding and treatment of diseases involving GABAA receptor dysfunction.

Effects of ethanol and deferoxamine on rat primary glial cell cultures, in regard with ischemia induced by traumatic spinal cord injury

Although they have been regarded, in the past, as passive support cells, many experimental data have shown that glial cells play a critical role in the development and functioning of the nervous system. Despite the advances that have been made in understanding astrocytes' role in the nervous system's development and function, our knowledge of their interactions with other cells is still limited, albeit neurons are dependent on the trophic support provided by astrocytes release. Materials and Methods. The use of the McCarthy and de Vellis methods for isolating glial cells has been regarded as an essential tool for studying their function. This study aims to evaluate the effects of ethanol and deferoxamine on primary rat glial cell cultures and try to explain, as far as possible, the relevance of such effects for patients with chronic alcoholism and traumatic spinal cord injuries. Discussion. Because glial cells are very important in the functioning of the central nervous system and experiments cannot be performed on human primary nerve cell cultures, we performed an experiment on glial cells harvested from the newborn rat, analyzing the dynamics of IL-6 and TNF alpha on models of suffering in spinal cord injury (hypoxia and thermally stress). Conclusion. Inhibition of TNF alpha synthesis was more important at 7 days posttraumatic in cells with prolonged ethanolic exposure, even if protein levels of IL-6 were elevated (under similar experimental conditions). Thus, we can say that long-term exposure to ethanol of nerve cells can ensure a favorable evolution of medical recovery (by increasing TNF alpha), even if the inflammatory process remains active (shown by elevated IL-6 values). Keywords: ethyl alcohol, deferoxamine, primary glial cells cultures, traumatic Spinal Cord Injury

Ontogenetic Oxycodone Exposure Affects Early Life Communicative Behaviors, Sensorimotor Reflexes, and Weight Trajectory in Mice

Nationwide, opioid misuse among pregnant women has risen four-fold from 1999 to 2014, with commensurate increase in neonates hospitalized for neonatal abstinence syndrome (NAS). NAS occurs when a fetus exposed to opioids in utero goes into rapid withdrawal after birth. NAS treatment via continued post-natal opioid exposure has been suggested to worsen neurodevelopmental outcomes. We developed a novel model to characterize the impact of in utero and prolonged post-natal oxycodone (Oxy) exposure on early behavior and development. Via subcutaneous pump implanted before breeding, C57BL/6J dams were infused with Oxy at 10 mg/kg/day from conception through pup-weaning. At birth, in utero oxy-exposed pups were either cross-fostered (paired with non-Oxy exposed dams) to model opioid abstinence (in utero Oxy) or reared by their biological dams still receiving Oxy to model continued post-natal opioid exposure (prolonged Oxy). Offspring from vehicle-exposed dams served as cross-fostered (in utero Veh) or biologically reared (prolonged Veh) controls. In utero Oxy exposure resulted in sex-dependent weight reductions and altered spectrotemporal features of isolation-induced ultrasonic vocalization (USV). Meanwhile, prolonged Oxy pups exhibited reduced weight and sex-differential delays in righting reflex. Specifically, prolonged Oxy female offspring exhibited increased latency to righting. Prolonged Oxy pups also showed decreases in number of USV calls and changes to spectrotemporal USV features. Overall, ontogenetic Oxy exposure was associated with impaired attainment of gross and sensorimotor milestones, as well as alterations in communication and affective behaviors, indicating a need for therapeutic interventions. The model developed here will enable studies of withdrawal physiology and opioid-mediated mechanisms underlying these neurodevelopmental deficits.

Initial researches on neuro-functional status and evolution in chronic ethanol consumers with recent traumatic spinal cord injury

We found differences related to the neuro-functional deficiency and clinical progress, among non-consumers and chronic consumers of ethanol, with recent traumatic spinal cord injury (SCI). We present a synthesis of related data on lesion mechanisms in post-traumatic myelogenous disorders, namely some of the alcohols and their actions on the nervous system, with details on the influences exerted, in such afflictions, by the chronic consumption of ethanol. The subject is not frequently approached – according to a literature review with systematic elements, which we have done before – thus constituting a niche that deserves to be further explored. The applicative component of the article highlights statistical data resulted from a retrospective study regarding the specialized casuistry from the Neuromuscular Recovery Clinic of the “Bagdasar Arseni” Emergency Clinical Hospital, following the comparative analysis of two groups of patients with recent SCI: non-consumers – the control group (n=780) – and chronic ethanol consumers – the study group (n=225) – with the addition of a prospective pilot component. Data processing has been achieved with SPSS 24. The American Spinal Injury Association Impairment Scale (AIS) mean motor scores differ significantly (tests: Mann-Whitney and t) between the control and study group in favor of the second, both at admission (p<0.001) and at discharge (p<0.001). AIS mean sensitive scores differ between the two lots, and also in favor of the study, but statistically significant only at discharge (p=0.048); the difference at admission is not significant (p=0.51) – possibly because of alcoholic-nutritional polyneuropathy. These findings, with numerous related details, later presented in the text, are surprising, which requires further studies and attempts of understanding.

Opioid receptor-mediated changes in the NMDA receptor in developing rat and chicken

The use of opioids during pregnancy has been associated with neurodevelopmental toxicity in exposed children, leading to cognitive and behavioural deficits later in life. The N-methyl-D-aspartate receptor (NMDAR) subunit GluN2B plays critical roles in cerebellar development, and methadone has been shown to possess NMDAR antagonist effect. Consequently, we wanted to explore if prenatal opioid exposure affected GluN2B subunit expression and NMDAR function in rat and chicken cerebellum. Pregnant rats were exposed to methadone (10 mg/kg/day) or buprenorphine (1 mg/kg/day) for the whole period of gestation, using an osmotic minipump. To further examine potential effects of prenatal opioid exposure in a limited time window, chicken embryos were exposed to a 20 mg/kg dose of methadone or morphine on embryonic days 13 and 14. Western blot analysis of cerebella isolated from 14 days old rat pups exposed to buprenorphine showed significantly lower level of the GluN2B subunit, while the opioid exposed chicken embryo cerebellar GluN2B expression remained unaffected at embryonic day 17. However, we observed increased NMDA/glycine-induced calcium influx in cerebellar granule neurone cultures from opioid exposed chicken embryos. We conclude that prenatal opioid exposure leads to opioid receptor-dependent reduction in the postnatal expression of GluN2B in rat cerebella, and increase in NMDA-induced calcium influx in chicken embryo cerebella.

Ethanol exposed maturing rat cerebellar granule cells show impaired energy metabolism and increased cell death after oxygen-glucose deprivation

Alcohol, a widely abused drug, has deleterious effects on the immature nervous system. This study investigates the effect of chronic in vitro ethanol exposure on the metabolism of immature rat cerebellar granular cells (CGCs) and on their response to oxygen-glucose deprivation (OGD). Primary CGC cultures were exposed to ethanol (100 mM in culture medium) or to control ethanol-free medium starting day one in vitro (DIV1). At DIV8, the expression of ATP synthase gene ATP5g3 was quantified using real-time PCR, then cultures were exposed to 3 hours of OGD or normoxic conditions. Subsequently, cellular metabolism was assessed by a resazurin assay and by ATP level measurement. ATP5g3 expression was reduced by 12-fold (P = 0.03) and resazurin metabolism and ATP level were decreased to 74.4 ± 4.6% and 55.5 ± 6.9%, respectively after chronic ethanol treatment compared to control values (P < 0.01). Additionally, after OGD exposure of ethanol-treated cultures, resazurin metabolism and ATP level were decreased to 12.7 ± 1.0% and 9.0 ± 2.0% from control values (P < 0.01). These results suggest that chronic ethanol exposure reduces the cellular ATP level, possibly through a gene expression down-regulation mechanism, and increases the vulnerability to oxygen-glucose deprivation. Thus, interventions which improve metabolic function and sustain ATP-levels could attenuate ethanol-induced neuronal dysfunction and should be addressed in future studies.

Effect of prenatal tramadol on postnatal cerebellar development: Role of oxidative stress

BACKGROUND AND AIM

The adverse neurological effects of tramadol have recently raised attention. The literature pertaining to studying postnatal cerebellar changes induced by prenatal tramadol is very scanty, thus the current study has been designed to improve understanding of the cerebellar oxidative stress-related alterations associated with tramadol administration during pregnancy in this critical period of neuronal differentiation and synaptic development, thereby highlighting the importance of controlling prenatal prescription of opioids and optimizing care for opioid-dependent pregnant women and their infants.

MATERIAL AND METHODS

Twenty pregnant female rats of Sprague Dawley strains were used in the study. Their offspring were divided into two groups: group I (control group) offspring of mothers given saline; group II offspring of mothers given tramadol from the 10th day (D10) of gestation till D21. The pups were sacrificed on the 7^th, 14^th and 21^st postnatal days. Cerebellar specimens were processed for histomorphometric, immunohistochemical and electron microscopic assessment and were evaluated for various oxidative stress parameters.

RESULTS

Tramadol administration during pregnancy caused profound structural abnormalities on the post-natal cerebellar cortex and was associated with oxidative stress evidenced by elevation of lipid peroxidation products and inhibition of antioxidant enzyme activities.

Opiate Drugs with Abuse Liability Hijack the Endogenous Opioid System to Disrupt Neuronal and Glial Maturation in the Central Nervous System

The endogenous opioid system, comprised of multiple opioid neuropeptide and receptor gene families, is highly expressed by developing neural cells and can significantly influence neuronal and glial maturation. In many central nervous system (CNS) regions, the expression of opioid peptides and receptors occurs only transiently during development, effectively disappearing with subsequent maturation only to reemerge under pathologic conditions, such as with inflammation or injury. Opiate drugs with abuse liability act to modify growth and development by mimicking the actions of endogenous opioids. Although typically mediated by μ-opioid receptors, opiate drugs can also act through δ- and κ-opioid receptors to modulate growth in a cell-type, region-specific, and developmentally regulated manner. Opioids act as biological response modifiers and their actions are highly contextual, plastic, modifiable, and influenced by other physiological processes or pathophysiological conditions, such as neuro-acquired immunodeficiency syndrome. To date, most studies have considered the acute effects of opiates on cellular maturation. For example, activating opioid receptors typically results in acute growth inhibition in both neurons and glia. However, with sustained opioid exposure, compensatory factors become operative, a concept that has been largely overlooked during CNS maturation. Accordingly, this article surveys prior studies on the effects of opiates on CNS maturation, and also suggests new directions for future research in this area. Identifying the cellular and molecular mechanisms underlying the adaptive responses to chronic opiate exposure (e.g., tolerance) during maturation is crucial toward understanding the consequences of perinatal opiate exposure on the CNS.

Alterations in postnatal neurogenesis and dopamine dysregulation in schizophrenia: a hypothesis

An increasing number of studies demonstrate the important role of several susceptibility genes for schizophrenia, such as neuregulin-1 and DISC1, in early postnatal and adult neurogenesis. Its significance for the pathophysiology of the disease, including its relation to neurotransmitter systems implicated in schizophrenia (like the dopamine system), remains, however, unknown. Here, we review molecular and cellular components of the dopamine system associated with postnatal neurogenesis and plasticity, both in rodents and in primates, and discuss their possible implication in schizophrenia. We focus mainly on the islands of Calleja, complex aggregations of granule cells in the ventral striatum, generated early postnatally in the subventricular zone. In contrast to the involution of the primate olfactory bulb, the islands of Calleja attain their maximal development in humans, an evolution paralleled by a larger ventral subventricular zone and more connections with other structures, including temporal cortical areas. The islands of Calleja express high levels of neuronal nitric oxide (NO) synthase and D3 dopamine receptors and are densely interconnected by dopaminergic projections with the ventral tegmental area. D3 receptors modulate subventricular zone neurogenesis and dopamine release. Their genetic deletion induces striatal hyperdopaminergia. We review data indicating a high plasticity of postnatal islands of Calleja, potentially facilitating susceptibility to schizophrenia-related risk factors. In this context, we propose a new pathophysiological model, where altered neurogenesis of the islands of Calleja may contribute to dysfunction of the dopamine and NO systems and psychosis through convergence of genetic and environmental disease-associated factors.

Brain anatomy of persistent violent offenders: more rather than less

Most violent crimes in Western societies are committed by a small group of men who display antisocial behavior from an early age that remains stable across the life-span. It is not known if these men display abnormal brain structure. We compared regional brain volumes of 26 persistently violent offenders with antisocial personality disorder and substance dependence and 25 healthy men using magnetic resonance imaging volumetry and voxel-based morphometry (VBM). The violent offenders, as compared with the healthy men, had markedly larger white matter volumes, bilaterally, in the occipital and parietal lobes, and in the left cerebellum, and larger grey matter volume in right cerebellum (effect sizes up to 1.24, P<0.001). Among the offenders, volumes of these areas were not associated with psychopathy scores, substance abuse, psychotropic medication, or global IQ scores. By contrast, VBM analyses of grey matter revealed focal, symmetrical, bilateral areas of atrophy in the postcentral gyri, frontopolar cortex, and orbitofrontal cortex among the offenders as compared with the healthy men (z-scores as high as 5.06). Offenders with psychopathy showed the smallest volumes in these areas. The larger volumes in posterior brain areas may reflect atypical neurodevelopmental processes that underlie early-onset persistent antisocial and aggressive behavior.

Neurogenesis and epilepsy in the developing brain

Multiple studies have highlighted how seizures induce different molecular, cellular, and physiologic consequences in an immature brain as compared to a mature brain. In keeping with these studies, seizures early in life alter dentate granule cell birth in different, and even opposing, fashion to adult seizure models (see Table 1). During the first week of rodent postnatal life, seizures decrease cell birth in the postictal period, but do not alter the maturation of newborn cells. Seizures during the second week of life have varied effects on dentate granule cell birth, either causing no change or increasing birth, and may promote a mild increase in neuronal survival. During the third and fourth weeks of life, seizures begin to increase cell birth similar to that seen in adult seizure models. Interestingly, animals that experienced seizure during the first month of life have an increase in cell birth during adulthood, opposite to the reported decrease in chronic animals experiencing a prolonged seizure as an adult. Children have more ongoing cell birth in the dentate gyrus than adults, and markers of cell division are further increased in children with refractory temporal lobe epilepsy. There are clear age-dependent differences in how seizures alter cell birth in the dentate gyrus both acutely and chronically. Future studies need to focus on how these changes in neurogenesis influence dentate gyrus function and what they imply for epileptogenesis and learning and memory impairments, so commonly found in children with temporal lobe epilepsy.

Canine cognitive dysfunction and the cerebellum: acetylcholinesterase reduction, neuronal and glial changes

The specific functional and pathological alterations observed in Alzheimer's disease are less severe in the cerebellum than in other brain areas, particularly the entorhinal cortex and hippocampus. Since dense core amyloid-beta plaque formation has been associated with an acetylcholinesterase heterogeneous nucleator action, we examined if an acetylcholinesterase imbalance was involved in cerebellum plaque deposition. By using the canine counterpart of senile dementia of the Alzheimer's type, a promising model of human brain aging and early phases of Alzheimer's disease, we investigated how cerebellar pathology and acetylcholinesterase density could be related with cognitive dysfunction. As in Alzheimer's disease, the late affectation of the cerebellum was evidenced by its lack of amyloid-beta plaque and the presence of diffuse deposition throughout all cortical grey matter layers. The highest acetylcholinesterase optic density corresponded to cerebellar islands of the granular layer and was predominantly associated with synaptic glomeruli and the somata of Golgi cells. Its reduction correlated with aging and loss of granule cells, whereas cognitive deficit only correlated with loss of Purkinje cells. The observed Bergmann glia alterations may correspond to a reactive response to the loss and damage of the Purkinje cells, their specific neuronal partner. Regarding the role of acetylcholinesterase mediation in amyloid-beta deposition, our data argue against an interaction between these two proteins because acetylcholinesterase reduction correlates with aging but not with cognitive deficit. Finally, our data support the use of companion dogs of all breeds to study aging and early phases of Alzheimer's disease.

HIV-1 neuropathogenesis: glial mechanisms revealed through substance abuse

Neuronal dysfunction and degeneration are ultimately responsible for the neurocognitive impairment and dementia manifest in neuroAIDS. Despite overt neuronal pathology, HIV-1 does not directly infect neurons; rather, neuronal dysfunction or death is largely an indirect consequence of disrupted glial function and the cellular and viral toxins released by infected glia. A role for glia in HIV-1 neuropathogenesis is revealed in experimental and clinical studies examining substance abuse-HIV-1 interactions. Current evidence suggests that glia are direct targets of substance abuse and that glia contribute markedly to the accelerated neurodegeneration seen with substance abuse in HIV-1 infected individuals. Moreover, maladaptive neuroplastic responses to chronic drug abuse might create a latent susceptibility to CNS disorders such as HIV-1. In this review, we consider astroglial and microglial interactions and dysfunction in the pathogenesis of HIV-1 infection and examine how drug actions in glia contribute to neuroAIDS.

In utero exposure to nicotine and chlorpyrifos alone, and in combination produces persistent sensorimotor deficits and Purkinje neuron loss in the cerebellum of adult offspring rats

This study was carried out to investigate the effect of in utero exposure to the cholinotoxicants, nicotine and chlorpyrifos, alone or in combination on neurobehavioral alterations and neuronal morphology latter in adult age. In the present study, 90 days old (corresponding to a human adult age) male and female offspring rats were evaluated for neurobehavioral, and neuropathological alterations following maternal, gestational exposure to nicotine and chlorpyrifos (O,O-diethyl-O-3,5,6-trichloro-2-pyridinyl phosphorothioate), alone and in combination. Female Sprague-Dawley rats (300-350 g) with timed-pregnancy were treated with nicotine (3.3 mg/kg/day, in bacteriostatic water via s.c. implantation of mini osmotic pump), chlorpyrifos (1.0 mg/kg, daily, dermal, in 75% ethanol, 1.0 ml/kg) or a combination of both chemicals, on gestational days (GD) 4-20. Control animals received bacteriostatic water via s.c. implantation of mini osmotic pump and dermal application of 70% ethanol. The offspring at postnatal day (PND) 90 were evaluated for neurobehavioral performance, changes in the activity of plasma butyrylcholinesterase (BChE) and acetylcholinesterase (AChE), and neuropathological alterations in the brain. Neurobehavioral evaluations included beam-walk score, beam-walk time, incline plane performance and forepaw grip time. Male and female offspring from mothers treated with nicotine and CPF, alone or in combination showed impairments in the performance of neurobehavioral tests, indicating sensorimotor deficits. Female offspring from mothers treated with a combination of nicotine and chlorpyrifos showed significant increase in plasma BChE activity. Brain regional AChE activity showed differential increases in male and female offspring. Brainstem and cerebellum of female offspring from mothers treated with nicotine or chlorpyrifos, alone or in combination showed increased AChE activity, whereas brainstem of male offspring from mothers treated with nicotine alone or a combination of nicotine and chlorpyrifos showed increase in AChE activity. Also, male offspring exposed in utero to nicotine exhibited increased AChE activity. Histopathological evaluations using cresyl violet staining showed a decrease in surviving Purkinje neurons in the cerebellum in offspring of all treatments groups. An increase in glial fibrillary acidic protein (GFAP) immuno-staining was observed in cerebellum white matter as well as granular cell layer (GCL) of cerebellum following all exposures. These results indicate that in utero exposure to nicotine and chlorpyrifos, alone and in combination produced significant sensorimotor deficits in male and female offspring, differential increase in brain AChE activity, a decrease in the surviving neurons and an increased expression of GFAP in cerebellum in adult offspring rats at a corresponding human adult age. Collectively, this study demonstrates that maternal exposure to environmental neurotoxic chemicals, i.e., nicotine and chlorpyrifos leads to developmental abnormalities in the offspring that persist latter into adulthood.

Reversal of neuronal migration in a mouse model of fetal alcohol syndrome by controlling second-messenger signalings

The brains of fetal alcohol syndrome patients exhibit impaired neuronal migration, but little is known about the mechanisms underlying this abnormality. Here we show that Ca2+ signaling and cyclic nucleotide signaling are the central targets of alcohol action in neuronal cell migration. Acute administration of ethanol reduced the frequency of transient Ca2+ elevations in migrating neurons and cGMP levels and increased cAMP levels. Experimental manipulations of these second-messenger pathways, through stimulating Ca2+ and cGMP signaling or inhibiting cAMP signaling, completely reversed the action of ethanol on neuronal migration in vitro as well as in vivo. Each second messenger has multiple but distinct downstream targets, including Ca2+/calmodulin-dependent protein kinase II, calcineurin, protein phosphatase 1, Rho GTPase, mitogen-activated protein kinase, and phosphoinositide 3-kinase. These results demonstrate that the aberrant migration of immature neurons in the fetal brain caused by maternal alcohol consumption may be corrected by controlling the activity of these second-messenger pathways.

Molecular targets of opiate drug abuse in neuroAIDS

Opiate drug abuse, through selective actions at mu-opioid receptors (MOR), exacerbates the pathogenesis of human immunodeficiency virus-1 (HIV-1) in the CNS by disrupting glial homeostasis, increasing inflammation, and decreasing the threshold for pro-apoptotic events in neurons. Neurons are affected directly and indirectly by opiate-HIV interactions. Although most opiates drugs have some affinity for kappa (KOR) and/or delta (DOR) opioid receptors, their neurotoxic effects are largely mediated through MOR. Besides direct actions on the neurons themselves, opiates directly affect MOR-expressing astrocytes and microglia. Because of their broad-reaching actions in glia, opiate abuse causes widespread metabolic derangement, inflammation, and the disruption of neuron-glial relationships, which likely contribute to neuronal dysfunction, death, and HIV encephalitis. In addition to direct actions on neural cells, opioids modulate inflammation and disrupt normal intercellular interactions among immunocytes (macrophages and lymphocytes), which on balance further promote neuronal dysfunction and death. The neural pathways involved in opiate enhancement of HIV-induced inflammation and cell death, appear to involve MOR activation with downstream effects through PI3-kinase/Akt and/or MAPK signaling, which suggests possible targets for therapeutic intervention in neuroAIDS.

Developmental Differences in Childhood Motor Coordination Predict Adult Alcohol Dependence: Proposed Role for the Cerebellum in Alcoholism

BACKGROUND

The Danish Longitudinal Study of Alcoholism has identified a number of early biological indicators that predicted alcohol dependence 30 years later. In light of recent evidence linking deficits of the cerebellum to certain neuropsychiatric disorders often comorbid with alcoholism, we hypothesized that developmental deficits in the cerebellar vermis may also play a role in the initiation of adult alcohol dependence. The present study evaluated whether measures of motor development in the first year of life predict alcohol dependence three decades later.

METHODS

A total of 241 subjects of the original 330 infants who were entered into this study completed the 30-year follow-up (12 had died). The subjects were men who were drawn from a large birth cohort born in Copenhagen, Denmark, from 1959 to 1961. A comprehensive series of measures were obtained on each subject before, during, and shortly after birth as well as at 1 year of age. Muscle tone at birth and day 5 as well as 1-year measures of motor coordination--age to sitting, standing, and walking--were examined. A DSM-III-R diagnosis of alcohol dependence and a measure of lifetime problem drinking served as the 30-year outcome variables.

RESULTS

Several measures of childhood motor development significantly predicted alcohol dependence at 30 years of age. These included deficits in muscle tone 5 days after birth, delays in the age to sitting, and delays in the age to walking.

CONCLUSIONS

Relationships found between adult alcoholism and early delays in motor development offer support for the theory that cerebellar deficits may play a causal role in the addiction process.

Depression of extra-cellular GABA and increase of NMDA-induced nitric oxide following acute intra-nuclear administration of alcohol in the cerebellar nuclei of the rat

Gamma-aminobutyric acid (GABA) and nitric oxide are two key-transmitters in cerebellar nuclei, the major output of cerebellar circuitry. The aims of this study were to investigate the effects of acute intra-cerebellar administration of ethanol (20 mM) on extra-cellular levels of GABA and on the NMDA-induced nitric oxide (NO) production using microdialysis in the rat. We also studied: (i) the effects of a pre-administration of DNQX, a specific antagonist of AMPA receptors, on NO production, (ii) the effects of a pre-administration of 7-NI (7-nitroindazole, an inhibitor of neuronal nitric oxide synthase NOS) and APV (D-2-amino-5-phosphonovaleric acid, a specific blocker of the NMDA type glutamate receptors) on the actions of alcohol/NMDA on glutamate receptors, and (iii) the in vivo interaction between DNQX, ethanol and NMDA receptor activation. We found that ethanol decreased the amount of extra-cellular GABA, and that this effect was counterbalanced by administration of tiagabine 1 mg/kg, a potent inhibitor of GAT-1 GABA transporter, given by the i.p. route. In loco administration of NMDA increased the levels of NO, as previously reported. A pre-administration of DNQX (500 microM) increased significantly the production of NO up to toxic levels, as well as ethanol administration. A pre-administration of 7-NI or APV reduced significantly the amounts of NO when NMDA and alcohol were infused simultaneously. The combination of ethanol with DNQX was associated with a marked enhancement of the concentrations of NO. The activity of GAT-1 in cerebellar nuclei and around this target, including in glial cells expressing GAT-1 activated by ambient GABA, seems to be spared by ethanol. Tiagabine could be considered as a candidate for future investigational treatments of acute ethanol-induced dysfunction of cerebellar nuclei. We found a potentiation of the production of NO when AMPA antagonists are given simultaneously to ethanol. The hypothesis of AMPA neurotoxicity, which has convincing arguments during chronic exposure, is challenged in this model of acute cerebellar nuclear toxicity of alcohol.

In utero nicotine exposure causes persistent, gender-dependant changes in locomotor activity and sensitivity to nicotine in C57Bl/6 mice

Maternal cigarette smoking during pregnancy can result in a wide variety of adverse fetal outcomes, ranging from preterm delivery and low birth weight, to sudden infant death syndrome. In addition, in utero tobacco smoke exposure is associated with delayed or impaired neuropsychological development. Although the causative agent in tobacco smoke that leads to these aberrations is not known, some studies have concluded that nicotine may play an important role. Many studies using animal models of prenatal nicotine exposure have supported the hypothesis that nicotine may directly and/or indirectly cause impairments in fetal and neonatal development. However, in many of the animal studies nicotine has been administered acutely to naive dams, which could lead to significant fetal hypoxia; some routes of drug administration are also very stressful to pregnant dams, and changes in stress hormones could also create an unfavorable fetal environment. In this study, pregnant mice were exposed to chronic nicotine via the drinking solution; locomotor activity and sensitivity to nicotine were evaluated in the offspring. We have previously shown that oral nicotine administration produces behavioral and physiological changes that resemble those seen following other routes of nicotine administration. Although oral nicotine exposure did not significantly alter any aspect of the pregnancy, dams drinking a nicotine-containing solution consumed approximately 20% less volume, compared to saccharin controls. All animals were cross fostered to nicotine naïve lactating dams, immediately after birth. On PN40 and PN60, male mice exposed to in utero nicotine demonstrated significant locomotor hyperactivity in an open filed arena. Although female animals did not show any signs of hyperactivity, they did have a significant attenuation of their hypothermic response to acute nicotine challenge. These results suggest that oral nicotine delivery to pregnant mice causes persistent, gender-dependant changes in behavior and sensitivity to nicotine. This model may be very useful for future studies that try to more accurately define the windows of sensitivity for nicotine exposure and the possible underlying neurochemical mechanisms involved.

Nicotinic cholinergic stimulation promotes survival and reduces motility of cultured rat cerebellar granule cells

Despite many studies on the functional expression of neuronal nicotinic acetylcholine receptors (nAChRs), an exhaustive description of the long-term effects of nicotine (Nic) stimulation in cerebellar granules is still far to be completed. For this reason, we addressed the experiments stimulating cultured cerebellar granule neurons (CGN) with Nic, focusing on the effects on cell motility and survival. Using electrophysiological and Ca(2+)-fluorescence techniques, we found a subset of rat CGN that responded to Nic by inward whole cell currents and by short-delay Ca(2+) transients. These responses were mediated through both homomeric and heteromeric nAChRs, as assessed by their sensitivity to alpha-bungarotoxin (alpha-BTX), dihydro-beta-erythroidine (DHbetaE), methyllicaconitine (MLA) and 5-hydroxyindole (5OH-indole). Once established the expression of alpha-BTX-sensitive and insensitive nAChRs and their ability to trigger Ca(2+) responses in CGN, we aimed at investigating their possible role on cell survival and motility. We demonstrate that Nic stimulation significantly increases the survival of CGN exposed to the apoptosis-promoting low K(+) medium. This anti-apoptotic effect is likely mediated through alpha7* nAChRs since we found that it was mimicked by choline, was insensitive to DHbetaE and was fully inhibited by alpha-BTX. Furthermore, we report that Nic negatively modulates CGN motility, reducing the basal cell movement through a pored membrane by the activation of alpha-BTX-insensitive nAChRs. We conclude that CGN express various types of nAChRs, which are differently involved in regulating Nic-mediated modulation of cell survival and migration, and we suggest potential regulatory roles for cholinergic receptors during cerebellar development.