Sodium nitroprusside inhibits the tyrosine hydroxylase activity of the median eminence in the rat.
Nitric oxide (NO) has been involved in the modulation of various neuroendocrine responses. This work is a study of dose-response and time-course of the effect of intracerebroventricular (i.c.v.) administration of (NO) generator sodium nitroprusside (SNP), on tyrosine hydroxylase (TH) activity of the median eminence (ME) and serum prolactin levels, performed on conscious male rats. SNP (1, 5 and 10 microg) inhibited the TH activity of the ME, 15 min following injection in a dose-dependent way, although the effect was only significant with the highest dose, and also increased in a dose-dependent manner the serum prolactin levels. Both actions were transient but vanished at different times following injection of 10 microg of SNP. These results suggest that NO, released from SNP, inhibits the tuberoinfundibular dopaminergic neurons of the basal hypothalamus to stimulate prolactin secretion.
González
M C
MC
Department of Physiology, School of Medicine, University of La Laguna, La Cuesta, Tenerife, Spain. mglezh@ull.es
Llorente
E
E
Abreu
P
P
D000818:Animals; D002552:Cerebral Ventricles / Q000187:drug effects / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D007276:Injections, Intraventricular; D007700:Kinetics; D008297:Male; D008473:Median Eminence / Q000201:enzymology*; D020030:Nitric Oxide Donors / Q000008:administration & dosage / Q000494:pharmacology; D009599:Nitroprusside / Q000008:administration & dosage / Q000494:pharmacology*; D011388:Prolactin / Q000097:blood; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors; D014446:Tyrosine 3-Monooxygenase / Q000037:antagonists & inhibitors / Q000378:metabolism*
D020030:Nitric Oxide Donors; D009599:Nitroprusside; D011388:Prolactin; D014446:Tyrosine 3-Monooxygenase