Measurement of VIP and origin of its innervation in the rat urinary bladder

Peptides and vasomotor mechanisms

The multiple and diverse roles played by neuropeptide Y, vasoactive intestinal polypeptide, substance P, calcitonin gene-related peptide and other biologically active peptides in the cardiovascular system are considered. A model of the vascular neuroeffector junction is described, which illustrates the interactions of peptidergic and nonpeptidergic transmitters that are possible at pre- and postjunctional sites. The effects of peptides on specific endothelial receptors are also described, which highlights the ability of these agents to act as dual regulators of vascular tone at both adventitial and intimal surfaces, following local release from nerves, or from endothelial cells themselves. Changes in expression of vascular neuropeptides that occur during development and aging in some disease situations and following nerve lesion are discussed.

Immunohistochemical evidence for extrinsic and intrinsic opioid systems in the guinea pig superior cervical ganglion

Immunohistochemical localization of the opioid peptides alpha-neo-endorphin (alpha-neo-END), dynorphin A (DYN) and leu-enkephalin (leu-ENK) in the guinea pig superior cervical ganglion (SCG) was studied following central denervation, peripheral axotomy, and after application of the depleting drug reserpine and of the neurotoxin 6-hydroxydopamine. The paraganglionic cells of the SCG are shown to form an intrinsic opioid--(alpha-neo-END, DYN, leu-ENK)--immunoreactive system being not visibly responsive to the experimental procedures. Leu-ENK-immunoreactive fibres ascend in the preganglionic trunk and supply fibre baskets to defined clusters of postganglionic neurones. Principal ganglion cells of the SCG containing alpha-neo-END- and DYN-immunoreactivity project to extraganglionic targets via the postganglionic nerves. These findings are indicative of a sympathetic alpha-neo-END-ergic and DYN-ergic innervation of effector organs. They also point to a modulatory function of opioids on neuronal activity in a paravertebral ganglion.

Selective facilitatory effect of vasoactive intestinal polypeptide (VIP) on muscarinic firing in vesical ganglia of the cat

VIP immunoreactivity was identified in nerve fibers and in 10-13% of the neurons in pelvic and bladder ganglia of the cat. Ninety percent of the VIP positive neurons contained acetylcholinesterase. VIP immunoreactivity was not altered in decentralized ganglia 1 week to 8 months after transection of the pelvic and hypogastric nerves indicating that VIP fibers arose from neurons within the peripheral nervous system. The intra-arterial administration of VIP (1-50 micrograms/kg) enhanced the postganglionic discharge elicited by the muscarinic agonist, acetyl-beta-methylcholine, but did not alter the postganglionic firing elicited by the nicotinic agonist, tetramethylammonium or by electrical stimulation of preganglionic axons in the pelvic nerve. VIP did not elicit a postganglionic discharge in untreated ganglia, but did evoke a prolonged discharge in ganglia treated with an irreversible anticholinesterase agent, 217AO. This discharge was not affected by hexamethonium but was blocked by atropine. VIP suppressed the muscarinic inhibition of ganglionic transmission produced by acetyl-beta-methylcholine without altering the response to other inhibitory agents (norepinephrine, leucine-enkephalin and gamma-aminobutyric acid (GABA). VIP (0.1-0.3 micrograms/kg) also had a direct inhibitory effect on bladder smooth muscle. These findings raise the possibility that intraganglionic pathways containing VIP may exert a selective modulatory influence on muscarinic transmission in vesical parasympathetic ganglia.

Origin and distribution of neuropeptide Y-, vasoactive intestinal polypeptide-and substance P-containing nerve fibers in the urinary bladder of the rat

The origin and distribution in the urinary bladder of nerve fibers containing neuropeptide Y (NPY), vasoactive intestinal polypeptide (VIP) and substance P (SP) were investigated in rats. Experimental procedures comprised preganglionic decentralization or postganglionic denervation of the bladder and also chemical sympathectomy as well as capsaicin treatment of newborn rats. Nerve fibers containing NPY were richly distributed in the detrusor muscle and also in the pelvic ganglia. Numerous NPY-containing nerve cell bodies were found in pelvic ganglia. A rich occurrence of VIP fibers and a more sparse distribution of SP-containing fibers were also found in the bladder as well as a relatively rich representation of VIP-containing nerve cell bodies in the pelvic ganglia. After decentralization the intensity of VIP and NPY immunofluorescence increased in nerve cell bodies of the pelvic ganglia and in nerve fibers in the wall of the bladder. Postganglionic denervation, on the other hand, eliminated all peptides examined in the bladder wall. After postganglionic denervation the situation in the ganglia was approximately the same as after decentralization. Chemical sympathectomy (6-OHDA) did not seem to change significantly the frequency and distribution of VIP-, SP- and NPY-fibers in the muscle layer of the bladder or in the pelvic ganglia, while the NPY-containing nerve fibers in the submucosal layer and around blood vessels of the bladder disappeared. Adrenergic nerve fibers in the wall of the bladder (visualized by histofluorescence) were markedly reduced in number after administration of 6-OHDA.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of vasoactive intestinal polypeptide on isolated urethral and urinary bladder smooth muscle from rabbit and man

Vasoactive intestinal polypeptide concentration-dependently inhibited the contractant responses of isolated preparations of the female rabbit bladder and urethra induced by electrical field stimulation and exogenous application of acetylcholine (bladder) and noradrenaline (urethra). The inhibition of alpha-adrenoceptor and muscarinic cholinoceptor-mediated activity in the urethra and bladder amounted to 50 to 90 per cent of induced contractions. The nonadrenergic noncholinergic contraction induced by electrical field stimulation in the urethra was reduced slightly, whereas corresponding response in the bladder was more sensitive. The maximum inhibition of both the electrically induced responses and contractions induced by exogenous noradrenaline and acetylcholine was of comparable size in the urethra and the bladder. The effects of vasoactive intestinal polypeptide seemed to be exerted postjunctionally since no significant influence of the peptide was seen on the release of 3H-noradrenaline from adrenergic nerve endings in the urethra. The effects of vasoactive intestinal polypeptide in human urethral and bladder preparations were less consistent. The noradrenaline-induced contraction in urethral preparations was inhibited by 29 +/- 9 per cent (no. = 22). The effects on electrically induced contractions in the urethra, and on responses to acetylcholine and electrical field stimulation in the bladder, were small and inconsistent. It is concluded that vasoactive intestinal polypeptide may be of importance for regulation of lower urinary tract smooth muscle activity in the rabbit. It cannot be excluded that the peptide has a modulatory role in neurotransmission in human urethral muscle. However, the present results do not support the view of vasoactive intestinal polypeptide as an inhibitor of contraction in human detrusor.