Effects of leucine-enkephalin on hypothalamic-pituitary-thyroid axis in rats.
Basal thyrotropin (TSH) levels in plasma and the TSH response to thyrotropin-releasing hormone (TRH) were inhibited after Leucine-enkephalin (L-EK) administration iv in rats. TRH and TSH responses to cold were inhibited after L-EK administration. In the L-DOPA, haloperidol or 5-hydoxytryptophan-treated rats, the inhibitory effect of L-EK on TSH release was restored. Findings suggested that L-EK acted both the hypothalamus and pituitary. Its inhibitory effects on TRH and TSH release at least partially mediated by interaction with amines in the central nervous system.
D000818:Animals; D003080:Cold Temperature; D004743:Enkephalin, Leucine / Q000494:pharmacology*; D007030:Hypothalamo-Hypophyseal System / Q000187:drug effects*; D008297:Male; D051381:Rats; D013961:Thyroid Gland / Q000187:drug effects*; D013972:Thyrotropin / Q000097:blood*; D013973:Thyrotropin-Releasing Hormone / Q000037:antagonists & inhibitors* / Q000097:blood; D013974:Thyroxine / Q000097:blood; D014284:Triiodothyronine / Q000097:blood
D014284:Triiodothyronine; D004743:Enkephalin, Leucine; D013973:Thyrotropin-Releasing Hormone; D013972:Thyrotropin; D013974:Thyroxine