Effect of chronic ethanol administration and abstinence on serum thyroid-stimulating hormone, prolactin and growth hormone concentrations in rats with high and low ethanol intake.

Serum anterior pituitary hormone levels of genetically selected AA and ANA rats of Wistar origin as well as those of experimentally selected heavy drinkers (HD) and light drinkers (LD) among normal Wistar rats were studied. AA and HD rats consumed high doses while ANA and LD rats preferred low doses of ethanol. Serum thyroid-stimulating hormone (TSH), prolactin and growth hormone (GH) concentrations were measured by specific radio-immuno-assays before chronic ethanol administration, during physical dependence and on subsequent withdrawal. Basal TSH levels and TSH responses to cold were as a rule decreased in the course of ethanol intake and abstinence, whereas the TRH-induced TSH elevation became more consistent than before ethanol. There was no difference in basal prolactin levels between ethanol preferring and non-preferring rats at abstinence, whereas 30 min cold-exposure seemed to decrease them in HD and LD rats. The high prolactin levels before ethanol and during physical dependence appear to be caused by stress factors involved in the blood collecting procedure. GH levels were not significantly different in ANA, AA, LD and HD rats and neither ethanol intake nor subsequent withdrawal consistently modified GH levels. It is concluded that the observed minor alterations in the levels of anterior pituitary hormones hardly play any significant role in the development of alcohol dependence.