Quantitative Immunocytochemistry of GABA and Synaptophysin in the Cerebellar Cortex of Old Ethanol-Fed Rats

Sex differences in stress-related alcohol use

Rates of alcohol use disorder (AUD) have increased in women by 84% over the past ten years relative to a 35% increase in men. This substantive increase in female drinking is alarming given that women experience greater alcohol-related health consequences compared to men. Stress is strongly associated with all phases of alcohol addiction, including drinking initiation, maintenance, and relapse for both women and men, but plays an especially critical role for women. The purpose of the present narrative review is to highlight what is known about sex differences in the relationship between stress and drinking. The critical role stress reactivity and negative affect play in initiating and maintaining alcohol use in women is addressed, and the available evidence for sex differences in drinking for negative reinforcement as it relates to brain stress systems is presented. This review discusses the critical structures and neurotransmitters that may underlie sex differences in stress-related alcohol use (e.g., prefrontal cortex, amygdala, norepinephrine, corticotropin releasing factor, and dynorphin), the involvement of sex and stress in alcohol-induced neurodegeneration, and the role of ovarian hormones in stress-related drinking. Finally, the potential avenues for the development of sex-appropriate pharmacological and behavioral treatments for AUD are identified. Overall, women are generally more likely to drink to regulate negative affect and stress reactivity. Sex differences in the onset and maintenance of alcohol use begin to develop during adolescence, coinciding with exposure to early life stress. These factors continue to affect alcohol use into adulthood, when reduced responsivity to stress, increased affect-related psychiatric comorbidities and alcohol-induced neurodegeneration contribute to chronic and problematic alcohol use, particularly for women. However, current research is limited regarding the examination of sex in the initiation and maintenance of alcohol use. Probing brain stress systems and associated brain regions is an important future direction for developing sex-appropriate treatments to address the role of stress in AUD.

ROCK1 Is Associated with Alzheimer's Disease-Specific Plaques, as well as Enhances Autophagosome Formation But not Autophagic Aβ Clearance

Alzheimer's disease (AD) is the most prevalent form of late-life dementia in the population, characterized by amyloid plaque formation and increased tau deposition, which is modulated by Rho-associated coiled-coil kinase 1 (ROCK1). In this study, we further analyze whether ROCK1 regulates the metabolism of amyloid precursor protein (APP). We show that ROCK1 is colocalized with mature amyloid-β (Aβ) plaques in patients with AD, in that ROCK1 enhances the amyloidogenic pathway, and that ROCK1 mediated autophagy enhances the intracellular buildup of Aβ in a cell model of AD (confirmed by increased ROCK1 and decreased Beclin 1 protein levels, with neuronal autophagosome accumulation in prefrontal cortex of AD APP/PS1 mouse model). In vitro over-expression of ROCK1 leads to a decrease in Aβ secretion and an increase in the expression of autophagy-related molecules. ROCK1 interacts with Beclin1, an autophagy initiator, and enhances the intracellular accumulation of Aβ. Reciprocally, overexpression of APP/Aβ promotes ROCK1 expression. Our data suggest ROCK1 participates in regulating Aβ secretion, APP shedding and autophagosome accumulation, and that ROCK1, rather than other kinases, is more likely to be a targetable enzyme for AD therapy.

d-LSD-induced c-Fos expression occurs in a population of oligodendrocytes in rat prefrontal cortex

Induction of mRNA or protein for immediate-early genes, such as c-fos, is used to identify brain areas, specific cell types, and neuronal circuits that become activated in response to various stimuli including psychoactive drugs. The objective of the present study was to identify the cell types in the prefrontal cortex in which lysergic acid diethylamide (d-LSD) induces c-Fos expression. Systemic administration of d-LSD resulted in a dose-dependent increase in c-Fos immunoreactivity. Although c-Fos-positive cells were found in all cortical layers, they were most numerous in layers III, IV, and V. d-LSD-induced c-Fos immunoreactivity was found in cells co-labeled with anti-neuron-specific enolase or anti-oligodendrocyte Oligo1. The Oligo1-labeled cells had small, round bodies and nuclear diameters characteristic of oligodendrocytes. Studies using confocal microscopy confirmed colocalization of c-Fos-labeled nuclei in NeuN-labeled neurons. Astrocytes and microglia labeled with glial fibrillary acidic protein antibody and OX-42 antibody, respectively, did not display LSD-induced c-Fos expression. Pyramidal neurons labeled with anti-neurofilament antibody also did not show induction of c-Fos immunoreactivity after systemic d-LSD administration. The present study demonstrates that d-LSD induced expression of c-Fos in the prefrontal cortex occurs in subpopulations of neurons and in oligodendrocytes, but not in pyramidal neurons, astrocytes, and microglia.

Differential adaptations in GABAergic and glutamatergic systems during ethanol withdrawal in male and female rats

BACKGROUND

There are significant and consistent sex differences in recovery from ethanol withdrawal in our animal model of ethanol dependence. We have also observed significant and varied sex differences in subunit protein levels of gamma-aminobutyric acid A (GABAA) and the N-metheyl-D-aspartate subtype of glutamate receptors occurring with ethanol dependence and withdrawal. Considering the major role of these two systems as targets of ethanol, we wanted to explore additional possible mechanisms underlying changes in GABAergic and glutamatergic responses after chronic ethanol exposure. Therefore, the objective of the present study was to examine GABAergic- and glutamatergic-associated proteins at three days of ethanol withdrawal, when female rats appear to have largely recovered but male rats still display robust signs of withdrawal.

METHODS

Male and female rats were fed 6% ethanol in a nutritionally complete liquid diet for 14 days according to a pair-fed design; withdrawal was initiated by replacement of the diet with chow. At three days of withdrawal, the cerebral cortex and hippocampus were dissected for use in Western blot analysis. The paired design was maintained throughout all experimental procedures.

RESULTS

At three days of ethanol withdrawal, we found region-specific and sex-selective alterations in levels of GAD (glutamic acid decarboxylase, GABA synthetic enzyme), GABA and glutamate transporters, and the synapse-associated proteins HSP70, PSD-95, and synaptophysin. There were also several significant differences in transporter function at this time that varied between males and females.

CONCLUSIONS

Taken together, these findings show differential adaptations of GABAergic and glutamatergic neurotransmission between female and male rats that are associated with withdrawal recovery. This suggests that selective withdrawal-induced neuroadaptations in regulation of these systems' activities underlie, at least in part, sex differences in withdrawal recovery between male and female rats.

Trace eyeblink conditioning in abstinent alcoholic individuals: effects of complex task demands and prior conditioning

Chronic misuse of alcohol affects an integrated neural circuit supporting the formation of associative memories acquired during eyeblink classical conditioning (R. McGlinchey-Berroth et al., 1995). The authors of this study investigated single-cue trace conditioning in amnesic and nonamnesic abstinent alcoholic individuals who either were or were not trained in a single-cue delay conditioning task. Overall, untrained alcoholic participants were severely impaired in acquisition, and alcoholic participants previously trained in single-cue delay conditioning performed similarly to untrained control participants. Individual performance in acquisition varied significantly within task but was relatively stable between the trace and delay tasks; there were nonamnesic and amnesic alcoholic participants who acquired responses at a normal rate in both delay and trace conditioning. The similarity of performances in delay and trace conditioning suggests a common source of impairment across both tasks.

Alcohol-Induced Neurodegeneration: When, Where and Why?

This manuscript reviews the proceedings of a symposium organized by Drs. Antonio Noronha and Fulton Crews presented at the 2003 Research Society on Alcoholism meeting. The purpose of the symposium was to examine recent findings on when alcohol induced brain damage occurs, e.g., during intoxication and/or during alcohol withdrawal. Further studies investigate specific brain regions (where) and the mechanisms (why) of alcoholic neurodegeneration. The presentations were (1) Characterization of Synaptic Loss in Cerebella of Mature and Senescent Rats after Lengthy Chronic Ethanol Consumption, (2) Ethanol Withdrawal Both Causes Neurotoxicity and Inhibits Neuronal Recovery Processes in Rat Organotypic Hippocampal Cultures, (3) Binge Drinking-Induced Brain Damage: Genetic and Age Related Effects, (4) Binge Ethanol-Induced Brain Damage: Involvement of Edema, Arachidonic Acid and Tissue Necrosis Factor alpha (TNFalpha), and (5) Cyclic AMP Cascade, Stem Cells and Ethanol. Taken together these studies suggest that alcoholic neurodegeneration occurs through multiple mechanisms and in multiple brain regions both during intoxication and withdrawal.