Effects of opioid peptides on immunoreactive corticotropin-releasing factor release from the rat hypothalamus in vitro.
Effects of opioid peptides on immunoreactive corticotropin-releasing factor (I-CRF) release from the rat hypothalamus were examined using a rat hypothalamic perifusion system and a rat CRF RIA in vitro. beta-Endorphin (0.3 - 30 nM), dynorphin (0.3 - 30 nM) and FK 33-824 (1 - 10 microM) suppressed basal I-CRF release in a dose-dependent fashion. At 2.2 nM concentrations of these peptides, mean percent inhibition was 56% for beta-endorphin; less than 5% for alpha-endorphin; 44% for dynorphin; 23% for leucine-enkephalin; 6% for methionine-enkephalin; less than 5% for FK 33-824; and less than 5% for D-ala2, D-leu5-enkephalin. The inhibitory effects of beta-endorphin and enkephalins were completely blocked by naloxone, but those of dynorphin were only partially blocked. These results suggest that opioid peptides act through opioid receptors and inhibit I-CRF release from the hypothalamus under our conditions. Therefore, endogenious opioid peptides may have a physiological role in the CRF-releasing mechanism of the hypothalamus.
Yajima
F
F
Suda
T
T
Tomori
N
N
Sumitomo
T
T
Nakagami
Y
Y
Ushiyama
T
T
Demura
H
H
Shizume
K
K
D000818:Animals; D003346:Corticotropin-Releasing Hormone / Q000276:immunology / Q000378:metabolism*; D005405:D-Ala(2),MePhe(4),Met(0)-ol-enkephalin / Q000494:pharmacology; D004399:Dynorphins / Q000494:pharmacology; D004723:Endorphins / Q000494:pharmacology*; D004745:Enkephalins / Q000494:pharmacology; D007031:Hypothalamus / Q000378:metabolism*; D066298:In Vitro Techniques; D008297:Male; D009270:Naloxone / Q000494:pharmacology; D011863:Radioimmunoassay; D051381:Rats; D012636:Secretory Rate / Q000187:drug effects
D004723:Endorphins; D004745:Enkephalins; D009270:Naloxone; D005405:D-Ala(2),MePhe(4),Met(0)-ol-enkephalin; D004399:Dynorphins; D003346:Corticotropin-Releasing Hormone