Correlations between neuronal nitric oxide synthase and muscarinic M3/M1 receptors in the rat retina.
This study determined the different signal pathways involved in M1/M3 muscarinic acetylcholine receptor (mAChR) dependent stimulation of nitric oxide synthase (NOS) activity/cyclic GMP (cGMP) production and nNOS mRNA expression in rat retina. Exposure of the retina to different concentrations of carbachol caused an increase in NOS activity, cGMP production and phosphoinositol (PI) accumulation. The increase in NOS activity and cGMP content was blocked by L-NMMA and ODQ, respectively. Also, phospholipase C (PLC) and calcium/calmodulin (CaM) inhibition prevented the carbachol activation on NOS/cGMP pathways. Both, 4-DAMP and pirenzepine but not AF-DX 116 blocked the increase in NOS and cGMP induced by carbachol. Carbachol-stimulation of M1/M3 mAChR increased nNOS-mRNA levels associated with an increase of endogenous NO and cGMP production. The mechanism appears to occur secondarily to stimulation of PIs turnover via PLC. This triggers a cascade reaction involving CaM and soluble guanylate cyclase leading to NO and cGMP accumulation, that in turn, up regulates nNOS-mRNA gene expression. These results give novel insight into the mechanism involved in the regulation of nNOS-mRNA levels by mAChR activation of retina.
Borda
Enri
E
Pharmacology Unit, School of Dentistry, University of Buenos Aires and Argentine National Research Council (CONICET), T. de Alvear 2142, 4 to. B 1122AAH Buenos Aires, Argentina. enri@farmaco.odon.uba.ar
Berra
Alejandro
A
Saravia
Mario
M
Ganzinelli
Sabrina
S
Sterin-Borda
Leonor
L
D000818:Animals; D002217:Carbachol / Q000494:pharmacology; D018679:Cholinergic Agonists / Q000494:pharmacology; D006152:Cyclic GMP / Q000096:biosynthesis; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D008297:Male; D018727:Muscarinic Antagonists / Q000494:pharmacology; D009474:Neurons / Q000201:enzymology*; D019001:Nitric Oxide Synthase / Q000032:analysis*; D010716:Phosphatidylinositols / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017208:Rats, Wistar; D011976:Receptors, Muscarinic / Q000032:analysis*; D012160:Retina / Q000187:drug effects / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology; D019323:omega-N-Methylarginine / Q000494:pharmacology
D018679:Cholinergic Agonists; D004791:Enzyme Inhibitors; D018727:Muscarinic Antagonists; D010716:Phosphatidylinositols; D012333:RNA, Messenger; D011976:Receptors, Muscarinic; D019323:omega-N-Methylarginine; D002217:Carbachol; D019001:Nitric Oxide Synthase; D006152:Cyclic GMP