Regulation of neuronal nitric oxide synthase mRNA expression in the rat magnocellular neurosecretory system.
We examined the activation of nNOS mRNA expression within the supraoptic and paraventricular nuclei (SON and PVN) of the hypothalamus. In salt-loaded rats nNOS mRNA expression was significantly increased in both nuclei. In rats given i.p. injections of 1.5 M NaCl (4 ml/kg), a small but significant increase in nNOS mRNA expression in the SON and PVN was found 6 h after injection; no change was detected 2 or 4 h after injection. In rats in which hyponatraemia had been induced experimentally, nNOS mRNA was downregulated in the SON, and expression levels were not increased within 4 h after intense acute osmotic stimuli. Finally, neurons of the SON were antidromically-activated by neural stalk stimulation for 2 h. No increase of nNOS mRNA expression in the SON was observed 2 h after stimulation. Thus, increased electrical activity is not directly coupled to rapidly increased expression of nNOS mRNA, and hence acute increases in nNOS mRNA expression are unlikely to play a role in short-term adaptation of the magnocellular system to osmotic stimulation.
School of Biomedical and Clinical Laboratory Sciences, College of Medicine and Veterinary Medicine, University of Edinburgh, George Square, Edinburgh EH8 9XD, UK.
Rungrudee
R
Srisawat
Valerie R
VR
Bishop
Philip M
PM
Bull
Alison J
AJ
Douglas
John A
JA
Russell
Mike
M
Ludwig
Gareth
G
Leng
D000704:Analysis of Variance; D000818:Animals; D002452:Cell Count / Q000379:methods; D004305:Dose-Response Relationship, Drug; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology*; D017403:In Situ Hybridization / Q000379:methods; D009490:Neurosecretory Systems / Q000187:drug effects / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000235:genetics / Q000378:metabolism*; D052248:Nitric Oxide Synthase Type I; D010286:Paraventricular Hypothalamic Nucleus / Q000166:cytology / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D012462:Saline Solution, Hypertonic / Q000494:pharmacology; D013495:Supraoptic Nucleus / Q000166:cytology / Q000378:metabolism; D013997:Time Factors
D012333:RNA, Messenger; D012462:Saline Solution, Hypertonic; D019001:Nitric Oxide Synthase; D052248:Nitric Oxide Synthase Type I; C496322:Nos1 protein, rat