Neuronal Nitric Oxide Synthase Activation by Vasoactive Intestinal Peptide in Bovine Cerebral Arteries

Abstract

Summary:The partIcipation of nitric oxide and vasoactive intestinal peptide (VIP) in the neurogenic regulation of bovine cerebral arteries was investigated, Nitrergic nerve fibers and ganglion-like groups of neurons were revealed by NADPH diaphorase staining in the adventitial layer of bovine cerebral arteries, NADPH diaphorase also was present in endothelial cells but not in the smooth muscle layer. Double immunola beling for neuronal nitric oxide synthase and VIP indicated that both molecules co-localized in the same nerve fibers in these vessels. Transmural nerve stimulation (200 rnA, 0.2 millisec onds, I to 8 Hz) of endothelium-denuded bovine cerebral artery rings precontracted with prostaglandin F2ex, produced tetrodo toxin-sensitive relaxations that were completely suppressed by AP-nitro-L-arginine methyl ester (L-NAME) and by the gua This work was supported by grant 94/0388 from the "Fondo de Investigaciones Sanitarias," Spain, and by PRAXIS XXI (BD/35751 94), Portugal. C Barroso is a recipient of an ENP short-term fellowship from the European Science Foundation. Ms. C. Martin is a recipient of a fellowship from the "Fondo de Investigaciones Sanitarias," Spain.Address correspondence and reprint requests to Dr. Carmen Estrada, Departamento de Fisiologfa, Facultad de Medicina, Universidad Au t6noma de Madrid, Arzobispo Morcillo I, 28029 Madrid, Spain.Abbreviations used: cAMP, cyclic AMP; cGMP, cyclic GMP; EC so , effective concentration 50; Emax, maximum effect; L-NAME, �-nitro L-arginine methyl ester; NANC, nonadrenergic noncholinergic; NO, nitric oxide; NOS, nitric oxide synthase; ODQ, lH-[1,2.4]oxadiazolo [4,3-a]quinoxaline; PBS, phosphate-buffered saline; SQ 22, 536, 9-(tet rahydro-2-furanyl)-9H-purin-6-amine; TNS, transmural nerve stimula tion; VIP, vasoactive intestinal peptide. 977VIP. Transmural nerve stimulation also elicited increases in intracellular cyclic GMP concentration, which were prevented by L-NAME, and small decreases in intracellular cyclic AMP concentration. Addition of VIP to bovine cerebral artery rings without endothelium produced a concentration-dependent re laxation that was partially inhibited by L-NAME, ODQ, and SQ 22,536. The effects of L-NAME and SQ 22,536 were additive. VIP induced a transient increase in intracellular cyclic GMP concentration, which was maximal I minute after VIP addition, when the highest relaxation rate was observed, and which was blocked by L-NAME. It is concluded that nitric oxide produced by perivascular neurons and nerve fibers fully accounts for the experimental neurogenic relaxation of bovine cerebral arteries and that VIP, which also is present in the same perivascular fibers, acts as a neuromodulator by activating neuronal nitric oxide synthase.

Pharmacology and Physiology of Perivascular Nerves Regulating Vascular Function

“…NE acts more likely on presynaptic adrenoceptors located on nitrergic nerves to cause release of NO, which then induces vasodilation. This conclusion is consistent with the reported biochemical findings that neurogenic vasodilation in cerebral arteries from different species induced by either TNS or nicotine is accompanied by an increase in cGMP but not cAMP (15,37,38), suggesting that the terminal transmitter acting on the smooth muscle to induce a relaxation is NO (known to increase cGMP synthesis) or a related substance but not NE (known to increase cAMP synthesis via its b -adrenoceptor action) (Fig. 1).…”

The Pharmacology of Nitric Oxide in the Peripheral Nervous System of Blood Vessels

“…Numerous histochemical and immunohistochemical studies have demonstrated that innervation of nitrergic nerves in the cerebral arteries are also observed in the guinea pig (Saito and Goto, 1994;Barroso et al, 1996), cat (Ayajiki et al, 1994;Kimura et al, 1997), monkey (Yoshida et al, 1994a;, pig (Sienkiewicz et al, 1995;Tanaka et al, 1999), cow (Toda and Okamura, 1996b;Gonzalez et al, 1997), sheep (Matthew, 1997), and human Gorelova et al, 1996). Porcine pial veins are also innervated by neurons containing NADPH diaphorase (Ishine et al, 1999).…”

Location and Function of VPAC1, VPAC2 and NPR-C Receptors in VIP-Induced Vasodilation of Porcine Basilar Arteries

“…Thus, inhibition of NO synthesis results in the attenuation of VIPinduced vasodilation of endothelium-denuded sheep middle cerebral arteries (Gaw et al, 1991) and bovine cerebral arteries (Gonzalez et al, 1997). In addition, the relaxant effect of VIP on isolated rat basilar arteries is inhibited by o-conotoxin or 7-nitroindazole (7-NI), showing that nitrergic neurons are activated by VIP (Seebeck et al, 2002).…”