Opioid modulation of vasopressin secretion in conscious rats.
To clarify the role of endogenous opioid peptides in the control of vasopressin (AVP) secretion, the effects of an endogenous kappa-agonist, leumorphin, derived from proenkephalin B and an opioid antagonist, naloxone, on AVP secretion were examined in conscious and freely moving rats. Intraperitoneal injection of nicotine markedly increased AVP secretion in rats. The nicotine-induced AVP secretion was significantly suppressed by intracerebroventricular (i.c.v.) pretreatment with leumorphin. Intravenous injection of naloxone significantly increased the basal AVP level and carbachol-induced AVP secretion. These results indicate that endogenous opioid peptides have an inhibitory effect on AVP secretion in rats.
Yamada
T
T
Second Division, Department of Medicine, Kyoto University School of Medicine, Japan.
Nakao
K
K
Itoh
H
H
Shirakami
G
G
Sugawara
A
A
Saito
Y
Y
Mukoyama
M
M
Arai
H
H
Hosoda
K
K
Morii
N
N
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002217:Carbachol / Q000494:pharmacology; D004723:Endorphins / Q000502:physiology*; D004745:Enkephalins / Q000494:pharmacology; D006339:Heart Rate / Q000187:drug effects; D008297:Male; D009270:Naloxone / Q000494:pharmacology; D009538:Nicotine / Q000494:pharmacology; D011498:Protein Precursors / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D014667:Vasopressins / Q000378:metabolism*
D004723:Endorphins; D004745:Enkephalins; D011498:Protein Precursors; D014667:Vasopressins; D009270:Naloxone; D009538:Nicotine; D002217:Carbachol; C033660:preproenkephalin