The Enkephalinergic System and Ethanol Effects

ABATE P; MÉNDEZ UBACH, MILAGROS; HERNANDEZ FONSECA K.

Neurosciece of alcohol: Mechanisms and Treatment

Book Aid - Elsevier

Lugar: Chennai; Año: 2019; p. 443 - 451

Alcohol (ethanol) is a depressant substance of thecentral nervous system that exhibits dose-dependentbiphasic effects on behavior. In animals and humans,low doses produce psychomotor activation and euphoria,whereas high doses decrease locomotor activity andinduce sedation (Lukas & Mendelson, 1988; Me´ndez &Herrera, 2012). The initial administration of low alcoholdoses may progressively induce consumption of higherdoses, leading to drug abuse and/or dependence. Thiscycle initiates with the activation of neural reinforcementand reward circuits, which may induce neuroadaptivechanges that progressively lead to drugdependence (Nestler, Hyman, & Malenka, 2001).Alcohol exhibits positive and negative reinforcementproperties that are crucial in drug-seeking behaviorand dependence (Koob, Sanna, & Bloom, 1998;Wise & Bozarth, 1987). Ethanol-induced activation ofDAergic transmission of the mesocorticolombic system(VTA, PFC, and NAcc) plays a key role in the mechanismsunderlying ethanol reinforcement and reward(Wise & Bozarth, 1987). Ethanol increases the firingrate of DAergic neurons in the VTA and DA synthesis,release and metabolism in the NAcc and the PFC (DiChiara & Imperato, 1985; Fadda, Mosca, Colombo, &Gessa, 1989; Gessa, Muntoni, Collu, Vargiu, & Mereu,1985). The stimulatory effect of ethanol on DA releasefrom the NAcc is considered a key event in the reinforcingactions of ethanol.