Codepletion of serotonin and TRH induces apparent supersensitivity of spinal TRH receptors.
Thyrotropin-releasing hormone (TRH), substance P (SP) and serotonin (5-HT) coexist in raphe efferents to the spinal cord. Lesions of these serotonergic projections by intracisternal injection of 5,7-dihydroxytryptamine (50 micrograms) in rat pups resulted in 93% and 65% decreases in 5-HT and TRH content of adult rat spinal cords, respectively. This codepletion induced a 30-40% increase in binding of [3H][3-Me-His2]TRH [( 3H]MeTRH) to TRH receptors. The affinity and pharmacological specificity of [3H]MeTRH binding to control and DHT-lesioned cords appeared closely similar.
D015116:5,7-Dihydroxytryptamine / Q000494:pharmacology; D000818:Animals; D005260:Female; D008297:Male; D051381:Rats; D011956:Receptors, Cell Surface / Q000378:metabolism*; D018025:Receptors, Thyrotropin-Releasing Hormone; D012701:Serotonin / Q000378:metabolism / Q000502:physiology*; D013116:Spinal Cord / Q000378:metabolism*; D013973:Thyrotropin-Releasing Hormone / Q000378:metabolism / Q000502:physiology*
D011956:Receptors, Cell Surface; D018025:Receptors, Thyrotropin-Releasing Hormone; D015116:5,7-Dihydroxytryptamine; D012701:Serotonin; D013973:Thyrotropin-Releasing Hormone