GENETICS OF ALCOHOLISM: ROLE OF THE ENDOGENOUS OPIOID SYSTEM
At the present time alcoholism is recognized as a metabolic disease exhibiting the clinical features of craving for alcohol, loss of control over drinking, tolerance and physical dependence on alcohol, while both epidemiological and experimental studies have demonstrated that genetic factors may be important in determining whether an individual has a high or low vulnerability to develop alcoholism. Evidence also indicates that alcoholism is not characterized by a single gene single allele inheritance. Instead it seems that multiple genes and environmental factors interact to increase or decrease an individual's vulnerability to become an alcoholic. Current research is aimed at investigating whether certain behavioral, physiological and biochemical markers are highly associated with the incidence of alcoholism. Among the biochemical markers currently under investigation is the endogenous opioid system and its implication in mediating the reinforcing effects of ethanol. It is the objective of this manuscript to review current research on: (a) the interactions of ethanol with the endogenous opioid system at the molecular level; (b) the existence of genetically determined differences in the response of the endogenous opioid system to ethanol between subjects at high and low risk for excessive ethanol consumption, as well as between lines of animals showing preference or aversion for ethanol solutions; (c) the decrease of alcohol consumption consumption following pretreatment with opioid antagonists; and (d) the possible use of specific opioid receptor antagonists together with behavioral therapy to modify drinking behavior, to control craving and to prevent relapse.
CHILDREN OF ALCOHOLICS. PREDICTORS FOR PSYCHOPATHOLOGY AND ADDICTION.
Children of alcoholics have a higher risk of alcoholism and psychopathology. Therefore, in 1993 the Amsterdam Institute for Addiction Research initiated a study on vulnerability markers and risk factors in children of alcoholics, aimed at identifying predictors for the development of psychopathology and addiction in children of alcoholics. This article provides a summary of the background, rationales and aims of the study. With more specific and sensitive biological vulnerability markers that indicate risk status, more effective preventive interventions might become available. The biochemical part of the study aims at answering the question whether adenylate cyclase is a vulnerability marker for alcoholism. The psychophysiological part is directed at event-related potentials during task performance to clarify the nature of the brain and cognitive functions that may underlie or relate to vulnerability to alcoholism. The third part, the psychological component, aims at possible psychological mechanisms of enhanced risk of addition in children of alcoholics as well as the relationship with childhood psychopathology.
MAGNESIUM DEFICIENCY IN ALCOHOLISM: POSSIBLE CONTRIBUTION TO OSTEOPOROSIS AND CARDIOVASCULAR DISEASE IN ALCOHOLICS.
Magnesium (Mg) deficiency occurs frequently in chronic alcoholism and may contribute to the increased incidence of osteoporosis and cardiovascular disease seen in this population. Mg deficiency is primarily due to renal Mg-wasting and is exacerbated by dietary Mg deprivation, gastrointestinal losses with diarrhea or vomiting, as well as concomitant use of drugs such as diuretics and aminoglycosides. Osteoporosis is prevalent in the alcoholic population. Mg deficiency may contribute to increased bone loss by its effects on mineral homeostasis. In Mg depletion, there is often hypocalcemia due to impaired parathyroid hormone (PTH) secretion, as well as renal and skeletal resistance to PTH action. Serum concentrations of 1,25-vitamin D are also low. These changes are seen with even mild degrees of Mg deficiency and may contribute to the metabolic bone disease seen in chronic alcoholics. Hypomagnesemia in alcoholics may also contribute to increased cardiovascular disease by altering platelet function. Mg deficiency has been demonstrated to enhance platelet reactivity. In these studies, Mg was shown to inhibit platelet aggregation against various aggregation agents. Patients with Mg deficiency were shown to have increased platelet aggregation that was normalized with Mg therapy. The antiplatelet effect of Mg may be related to the finding that Mg inhibits the synthesis of thromboxane A2 and 12-hydroxyeicosatetraenoic acid, eicosanoids thought to be involved in platelet aggregation. Mg also inhibits the thrombin-induced Ca2+ influx in platelets, as well as stimulates synthesis of prostaglandin I2, the potent antiaggregatory eicosanoid. Therefore, Mg deficiency may increase platelet aggregation and cause increased hypertension and atherosclerotic cardiovascular disease in alcoholics.