Central inhibition of nitric oxide synthase preferentially augments release of oxytocin during dehydration.
Intracerebroventricular (i.c.v.) administration of NG-monomethyl-L-arginine monoacetate (NMMA; 500 micrograms; 402 mM) and NG-nitro-L-arginine methyl ester (NAME; 270 micrograms; 200 mM), inhibitors of nitric oxide synthase, enhanced the rise in oxytocin but not vasopressin levels in plasma of conscious rats following 24 h of water deprivation. This effect of NMMA occurred by 10 min after administration, reached its peak at 15 min and decreased by 20 min. Daily administration of lower doses (50 micrograms and 0.5 microgram/5 microliter, i.c.v.) of another inhibitor of nitric oxide synthase, NG-nitro-L-arginine, just before and after 24 h of water deprivation and in control animals treated similarly were without effect on either vasopressin or oxytocin levels. Nitric oxide, therefore, attenuates preferentially the release of oxytocin during dehydration.
Summy-Long
J Y
JY
Department of Pharmacology, M.S. Hershey Medical Center, Pennsylvania State University, Hershey 17033.
Bui
V
V
Mantz
S
S
Koehler
E
E
Weisz
J
J
Kadekaro
M
M
D000594:Amino Acid Oxidoreductases / Q000037:antagonists & inhibitors*; D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives* / Q000494:pharmacology; D003681:Dehydration / Q000503:physiopathology*; D008297:Male; D019331:NG-Nitroarginine Methyl Ester; D009419:Nerve Tissue Proteins / Q000037:antagonists & inhibitors*; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase; D010121:Oxytocin / Q000378:metabolism*; D010286:Paraventricular Hypothalamic Nucleus / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D010904:Pituitary Gland, Posterior / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013495:Supraoptic Nucleus / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D014667:Vasopressins / Q000378:metabolism; D019323:omega-N-Methylarginine
D009419:Nerve Tissue Proteins; D014667:Vasopressins; D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D010121:Oxytocin; D001120:Arginine; D019001:Nitric Oxide Synthase; D000594:Amino Acid Oxidoreductases; D019331:NG-Nitroarginine Methyl Ester