CHRONIC ETHANOL DRINKING AND FOOD-DEPRIVATION AFFECT RAT HYPOTHALAMIC-PITUITARY-THYROID AXIS AND TRH IN SEPTUM

Because chronic ethanol ingestion may perturb thyroid function, we eva luated the effect of 4-wk of oral 10% ethanol ingestion on the hypotha lamic-pituitary-thyroid (HPT) axis and septal thyrotropin-releasing ho rmone :TRH) in 200-g male Wistar rats. Animals were divided into three groups: absolute control receiving tap water and food adlibitum; etha nol group receiving food ad libitum and 10% ethanol as the sole source of drinking fluid; pair-fed group receiving tap water and an amount o f food corresponding to the consumpt on of ethanol group. After 4-wk o f treatment, the body weight of the ethanol group was 7% and of the pa ir-fed rats 19% lower than that of the absolute controls. Both chronic ethanol treatment and food depr vation produced a decrease in plasma thyroid-stimulating hormone (TSH). Fair-fed rats also had a lower plas ma T-3. Type I iodothyronine 5'-deiodinase activity in the liver was i ncreased in the pair-fed and even morel in the ethanol-treated group. The content and secretion in vitro of TRH from the hypothalamic parave ntricular nucleus and median eminence were unchanged. TRH content in t he septum was increased in both the ethanol and pair-fed groups. TRH s ecretion from the septum in vitro was lower in the pair-fed, blot unch anged in the ethanol group. These data suggest that 4-wk of peroral et hanol intake affects thyroid function mostly at the extrahypothalamic level and that there is a contribution of concomitant food deprivation . Both ethanol treatment and food deprivation increased TRH content in the septum.