Effects of serotonergic system on hypothalamic-pituitary-thyroid axis in rats.
The effects of the serotonergic system on the hypothalamic-pituitary-thyroid axis in rats were studied. Immunoreactive thyrotropin releasing hormone (ir-TRH) in plasma significantly increased 24 hours after para-chlorophenylalanine (PCPA) administration. Basal thyrotropin (TSH) levels in plasma significantly decreased after tryptophan or 5-hydroxytryptophan (5-HTP) administration, but not after PCPA administration. The plasma ir-TRH and TSH responses to cold were inhibited after tryptophan or 5-HTP administration, but not after PCPA treatment. In these treated groups, the TSH response to TRH did not differ from that of control. Thyroxine, 3,3',5-triiodothyronine showed no change after administration of these drugs. These data indicate that the serotonergic system might inhibit TRH and TSH release in rats.
D000818:Animals; D010134:Fenclonine / Q000494:pharmacology; D007030:Hypothalamo-Hypophyseal System / Q000502:physiology*; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D012701:Serotonin / Q000494:pharmacology / Q000502:physiology*; D013961:Thyroid Gland / Q000502:physiology*; D013972:Thyrotropin / Q000097:blood; D013973:Thyrotropin-Releasing Hormone / Q000494:pharmacology; D014364:Tryptophan / Q000494:pharmacology
D012701:Serotonin; D013973:Thyrotropin-Releasing Hormone; D014364:Tryptophan; D013972:Thyrotropin; D010134:Fenclonine