Effects of chronic alcohol consumption and withdrawal on the cholinergic neurons of the pedunculopontine and laterodorsal tegmental nuclei of the rat: An unbiased stereological study

Synaptic Effects Induced by Alcohol

Ethanol (EtOH) has effects on numerous cellular molecular targets, and alterations in synaptic function are prominent among these effects. Acute exposure to EtOH activates or inhibits the function of proteins involved in synaptic transmission, while chronic exposure often produces opposing and/or compensatory/homeostatic effects on the expression, localization, and function of these proteins. Interactions between different neurotransmitters (e.g., neuropeptide effects on release of small molecule transmitters) can also influence both acute and chronic EtOH actions. Studies in intact animals indicate that the proteins affected by EtOH also play roles in the neural actions of the drug, including acute intoxication, tolerance, dependence, and the seeking and drinking of EtOH. The present chapter is an update of our previous Lovinger and Roberto (Curr Top Behav Neurosci 13:31-86, 2013) chapter and reviews the literature describing these acute and chronic synaptic effects of EtOH with a focus on adult animals and their relevance for synaptic transmission, plasticity, and behavior.

Estimating Income-Related Health Inequalities Associated with Tobacco and Alcohol Consumption in Namibia

Disparities in resources and access to material opportunities are important determinants of income-related health inequality. This paper hypothesises that the gradient of the inequality in health between the poor and the rich is likely to depend on differences in lifestyle practices including tobacco use and alcohol abuse. Using the 2015/16 Namibia Household Income and Expenditure Survey and the Erreygers corrected concentration index, we estimate the effect of tobacco and alcohol use on income-related health inequalities. A decomposition technique was used to estimate the separate and joint contribution of tobacco and alcohol use to income-related health inequalities. The results indicate that tobacco use widens the income-related health inequality gap while alcohol consumption reduces health disparities. The simultaneous consumption of these goods has a stronger multiplicative effect on income-related health inequality. For instance, the simultaneous consumption of both goods contribute up to 1.03% of the inequality in health while tobacco use alone contributed only 0.6%. While policy options for each of these goods could be essential in reducing inequalities in health, there is a need to advocate additional measures that could simultaneously control the consumption of both goods.

Effects of aging on the cholinergic innervation of the rat ventral tegmental area: A stereological study

Dopamine neurons in the ventral tegmental area (VTA) play a main role in processing both rewarding and aversive stimuli, and their response to salient stimuli is significantly shaped by afferents originating in the brainstem cholinergic nuclei. Aging is associated with a decline in dopaminergic activity and reduced response to positive reinforcement. We have used stereological techniques to examine, in adult and aged rats, the dopaminergic neurons and the cholinergic innervation of the VTA, and the cholinergic populations of the pedunculopontine tegmental (PPT) and laterodorsal tegmental (LDT) nuclei, which are the only source of cholinergic inputs to the VTA. In the VTA, there were no age-related variations in the number and size of tyrosine hydroxylase (TH)-immunoreactive neurons, but the density of cholinergic varicosities was reduced in aged rats. The total number of choline acetyltransferase (ChAT)-immunoreactive neurons in the PPT and LDT was unchanged, but their somas were hypertrophied in aged rats. Our results suggest that dysfunction of the cholinergic system might contribute for the age-associated deterioration of the brain reward system.

Categorising a problem: alcohol and dementia

Alcoholism is a chronic relapsing disorder that can include extended periods of abstinence followed by relapse to heavy drinking. Decades of evidence have clearly shown that long-term, chronic ethanol exposure produces brain damage in humans. The article aims to review the relationship between alcohol use and dementia. Medline and Google Scholar searches were conducted for relevant articles, chapters and books published until 2019. Search terms used included alcohol consumption, alcohol-related dementia, alcohol use disorders, chronic alcoholism, dementia. Publications found through this indexed search were reviewed for further relevant references. Alcohol acts on the central nervous system via both direct and indirect effects, frequently a combination of the two. There is consensus that alcohol contributes to the acquisition of cognitive deficits in late life. However, there are doubts regarding the aetiopathogenesis, nosological status and prevalence of alcohol-related dementia and still, there is much debate over how much alcohol consumption will lead to alcohol-related dementia.

Aberrations in Incentive Learning and Responding to Heroin in Male Rats After Adolescent or Adult Chronic Binge-Like Alcohol Exposure

BACKGROUND AND PURPOSE

Binge drinking is a serious problem among adolescents and young adults despite its adverse consequences on the brain and behavior. One area that remains poorly understood concerns the impact of chronic intermittent ethanol (CIE) exposure on incentive learning.

METHODS

Here, we examined the effects of CIE exposure during different developmental stages on conditioned approach and conditioned reward learning in rats experiencing acute or protracted withdrawal from alcohol. Two or 21 days after adolescent or adult CIE exposure, male rats were exposed to pairings of a light stimulus (CS) and food pellets for 3 consecutive daily sessions (30 CS-food pellet pairings per session). This was followed by conditioned approach testing measuring responses (food trough head entries) to the CS-only presentations and by conditioned reward testing measuring responses on a lever producing the CS and on another producing a tone. We then measured behavioral sensitization to repeated injections of heroin (2 mg/kg/d for 9 days).

RESULTS

Adolescent and adult alcohol-treated rats showed significantly impaired conditioned reward learning regardless of withdrawal period (acute or prolonged). We found no evidence of changes to conditioned approach learning after adolescent or adult exposure to CIE. Finally, in addition to producing long-term impairments in incentive learning, CIE exposure enhanced locomotor activity in response to heroin and had no effect on behavioral sensitization to heroin regardless of age and withdrawal period.

CONCLUSIONS

Our work sets a framework for identifying CIE-induced alterations in incentive learning and inducing susceptibility to subsequent opioid effects.

Relationship of Wine Consumption with Alzheimer's Disease

BACKGROUND

Alzheimer's disease (AD), the most threatening neurodegenerative disease, is characterized by the loss of memory and language function, an unbalanced perception of space, and other cognitive and physical manifestations. The pathology of AD is characterized by neuronal loss and the extensive distribution of senile plaques and neurofibrillary tangles (NFTs). The role of environment and the diet in AD is being actively studied, and nutrition is one of the main factors playing a prominent role in the prevention of neurodegenerative diseases. In this context, the relationship between dementia and wine use/abuse has received increased research interest, with varying and often conflicting results. Scope and Approach: With this review, we aimed to critically summarize the main relevant studies to clarify the relationship between wine drinking and AD, as well as how frequency and/or amount of drinking may influence the effects. Key Findings and Conclusions: Overall, based on the interpretation of various studies, no definitive results highlight if light to moderate alcohol drinking is detrimental to cognition and dementia, or if alcohol intake could reduce risk of developing AD.