Opiate inhibition of K+-induced TRH release from superfused mediobasal hypothalami in rats.
The effect of morphine and leucine enkephalin on basal and K+-induced TRH release by superfused mediobasal hypothalami in rats was investigated in an oxygenated modified Locke medium at 37 degrees C during 10 min. Both opiates (morphine, 10(-6) M; leucine enkephalin, 10(-6) M) did not modify the spontaneous release of TRH, but significantly decreased the depolarization-induced TRH release. Naloxone (10(-6) M) had no effect when added alone to the medium, but reversed the opiate inhibition of TRH release. The data suggest that endogenous opiates exert a modulatory action on TRH nerve endings in the mediobasal hypothalami, probably through presynaptic specific opiate receptors.
D000818:Animals; D004743:Enkephalin, Leucine / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D007031:Hypothalamus / Q000378:metabolism*; D066298:In Vitro Techniques; D008297:Male; D009020:Morphine / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D009270:Naloxone / Q000008:administration & dosage; D011188:Potassium / Q000037:antagonists & inhibitors*; D051381:Rats; D011919:Rats, Inbred Strains; D013973:Thyrotropin-Releasing Hormone / Q000378:metabolism*
D009270:Naloxone; D004743:Enkephalin, Leucine; D013973:Thyrotropin-Releasing Hormone; D009020:Morphine; D011188:Potassium