Interaction of TRH and CCK in the satiation of alcohol intake

Alcohol, appetite and energy balance: is alcohol intake a risk factor for obesity?

The increased recognition that the worldwide increase in incidence of obesity is due to a positive energy balance has lead to a focus on lifestyle choices that may contribute to excess energy intake, including the widespread belief that alcohol intake is a significant risk factor for development of obesity. This brief review examines this issue by contrasting short-term laboratory-based studies of the effects of alcohol on appetite and energy balance and longer-term epidemiological data exploring the relationship between alcohol intake and body weight. Current research clearly shows that energy consumed as alcohol is additive to that from other dietary sources, leading to short-term passive over-consumption of energy when alcohol is consumed. Indeed, alcohol consumed before or with meals tends to increase food intake, probably through enhancing the short-term rewarding effects of food. However, while these data might suggest that alcohol is a risk factor for obesity, epidemiological data suggests that moderate alcohol intake may protect against obesity, particularly in women. In contrast, higher intakes of alcohol in the absence of alcohol dependence may increase the risk of obesity, as may binge-drinking, however these effects may be secondary to personality and habitual beverage preferences.

Chronic ethanol or glucose consumption alter TRH content and pyroglutamyl aminopeptidase II activity in rat limbic regions

Thyrotropin-releasing hormone (TRH), its receptors and inactivating enzyme (PPII) are present in limbic regions. Nutritional changes or acute ethanol administration in male rats differentially modulate TRH or PPII expression. Chronic ethanol effect was studied in male (3, 6 and 8 weeks) and female rats (6 weeks) including naive and pair-fed (glucose) groups. Daily solid food and liquid intake, serum TSH and corticosterone, TRH content and PPII activity in limbic regions, were quantified. Gender differences were found in ethanol and total caloric intake and body weight gain, TSH and corticosterone levels. Ethanol consumption decreased TRH content and PPII activity in frontal cortex of male rats after 3-6 weeks. In contrast, glucose ingestion altered, by the third week, TRH content in amygdala, hippocampus, hypothalamus and nucleus accumbens, PPII activity in hippocampus and frontal cortex; by the sixth week, TRH content in amygdala and n. accumbens of male and females. Withdrawal at 24 h after 3-week ethanol ingestion decreased TRH content in amygdala and PPII activity in n. accumbens, while withdrawal from glucose reverted some of the effects produced by chronic glucose ingestion. Variations in TRH content or PPII activity support a region specific involvement of TRH neurons that depend on the treatment.