The dose-dependent effects of alcohol, where the initial euphoric and stimulant effects initiated by the exposure to low ethanol levels can quickly lead to a deadly consequence are well established. Thus, high blood alcohol concentration (BAC), as seen in alcoholics, can cause significant damage to various organs. At low concentrations (e.g., 10 mg% or lower), however, beneficial effects of alcohol, particularly on cardiovascular function have been reported. Although, the latter assertion has been challenged by recent epidemiological studies, protective effects of low alcohol concentrations in vitro and in vivo relevant to the central nervous system (CNS) is well documented. In this review, the mechanism(s) leading to the detrimental effects of high BAC, as well as the beneficial effects of low BAC will be discussed. In addition, gender consideration is touched upon. Although further investigation is clearly warranted, it may be concluded that at least some of the beneficial outcomes of low BAC, including possible neuroprotection and antidepressant-like effects, may be due to elevation of the neurotropic factors and reduction of inflammatory mediators, whereas detrimental outcomes associated with high BAC, including neurotoxicity and depressive-like behavior may be due to reduction in neurotropic factors and elevation of inflammatory mediators. Furthermore, new research strategies are suggested.
Keywords: Inflammatory mediators; Major depressive disorder; Neuroprotection; Neurotoxicity; Neurotrophic factors; Sex differences.