Effect Of Unilateral Vagotomy Research Articles

The effects of unilateral truncal vagotomy on gastric carcinogenesis in hypergastrinemic Japanese female cotton rats

The stomach is innervated by the vagal nerve. Several studies have demonstrated that the vagal nerve has a trophic effect on the rat oxyntic mucosa and that the trophic effect of hypergastrinemia is dependent on intact vagal innervation. The effect of vagal denervation on gastric carcinogenesis has been examined in Mastomys natalensis and hypergastrinemic transgenic INS-GAS mice, with no effect of unilateral vagotomy in Mastomys but an anti-carcinogenic effect in INS-GAS mice.A proportion of female Japanese cotton rats develop spontaneous hypergastrinemia and ECL cell derived gastric carcinomas. In the current study we have examined the effects of unilateral anterior subdiaphragmatic vagotomy on gastric carcinogenesis. Female Japanese cotton rats were operated with unilateral anterior vagotomy or sham-operation at age 2months and were terminated at age 10months. Ten of fifteen animals operated by anterior vagotomy and 11 of 16 sham-operated developed hypergastrinemia. Vagotomy did not affect intragastric pH or serum gastrin. When comparing the anterior and posterior sides of the stomachs, vagotomy did not affect the occurrence of dysplasia or carcinoma development in the oxyntic mucosa. However, vagotomy resulted in lower stomach weight and reduced oxyntic mucosal thickness on the anterior side. Vagotomy also resulted in a reduction in volume density of chromogranin A positive cells in the oxyntic mucosa.In conclusion, vagotomy reduced the trophic effects of hypergastrinemia on the ECL cell and oxyntic mucosa, but did not prevent gastric carcinogenesis in female Japanese cotton rats. The effects of vagotomy on gastric carcinogenesis in animal models are conflicting and further studies in patients should be done to clarify the clinically significant effects of vagotomy.

Effects of unilateral vagotomy on nitric oxide synthase and histamine H 3 receptors in the rat dorsal vagal complex

Nitric oxide synthase (NOS) and histamine H 3 receptors are both markedly increased by neuronal injuries. To examine whether peripheral axotomy produced differential changes in NOS and H 3 receptors, both NOS and H 3 receptors were measured in the dorsal vagal complex after unilateral vagotomy. The presence of NOS-positive neurons was examined using both NADPH-diaphorase histochemistry and neuronal NOS-immunohistochemistry in rats vagotomized at the mid-cervical level. NADPH-diaphorase activity and NOS-immunoreactivity were markedly enhanced on the dorsal motor nucleus of the vagus (DMX) and in the ambiguus nucleus at the denervated side. Intraperitoneal injection of NOS inhibitors, N ω-nitro-L-arginine (10 mg/kg) or dexamethasone (0.5 mg/kg) attenuated the increase in NADPH-diaphorase activity. Glial fibrillary acidic protein (GFAP) was similarly induced 2 weeks after vagotomy in the vagal complex and surrounding area. Histamine H 3 receptors in the vagal complex were visualized with [ 3H]N α-methylhistamine. The ligand-labeled H 3 receptors were mainly located at the nucleus of the solitary tract (NST). The densities of H 3 receptors did not change in the NST after unilateral vagotomy. These results suggest that peripheral axotomy such as mid-cervical vagotomy preferentially induces NOS in damaged neurons without affecting the level of H 3 receptors.

Postvagotomy changes in neurogenic plasma extravasation in rat bronchi

The present study was carried out to test if plasma extravasation induced by capsaicin (90 μg/kg) in the bronchi of Sprague-Dawley rats could be reduced 10–30 min (0 day), 20–24 h (1 day), 3, 7 or 14 days after unilateral midcervical vagotomy. The second aim of this study was to demonstrate if substance P (3 μg/kg) could intensify neurogenic plasma extravasation in the bronchi in which sensory innervation was partially deprived by vagotomy. In the rats 0 days after vagotomy (0 days postvagotomy) that received capsaicin, plasma extravasation in the mainstem and secondary bronchi ipsilateral to vagotomy did not decrease. Capsaicin-evoked plasma extravasation in the secondary bronchi ipsilateral to vagotomy decreased significantly 1, 3, 7 and 14 days after vagotomy as compared with that of 0 days postvagotomy. Differences in extravasation between the secondary bronchi of the two sides were usually significant in animals 3, 7 or 14 days postvagotomy. The effect of unilateral vagotomy on plasma extravasation in the mainstem bronchi was variable. Plasma extravasation produced by substance P in the mainstem and secondary bronchi of rats 0 days postvagotomy was similar to that of unoperated rats receiving either capsaicin or substance P. Unilateral vagotomy did not decrease the amount of substance-P-induced plasma extravasation in the mainstem or secondary bronchi ipsilateral to vagotomy in rat groups 1, 3, 7 or 14 days postvagotomy as compared with that of their contralateral bronchi. This study suggests that the secondary bronchi were the chief location of the bronchial tree that could be desensitized after unilateral cervical vagotomy to stimulation by the irritant capsaicin. This desensitization developed within 1 day after vagotomy, therefore the capsaicin-evoked neurogenic inflammation in the bronchi of the vagotomized side was reduced. Exogenous substance P resulted in mucosal edema and degranulation of goblet cells in the bronchi of both vagotomized and opposite sides. The number of mediator-sensitive blood venules did not decrease following vagotomy operation. It is suggested that substance P was insufficient after vagal denervation, but substance-P receptors on the endothelial cells and goblet cells in the denervated regions were still operative.

Opiate receptor subtypes in the nucleus tractus solitarii of the cat: the effect of vagal section

The distribution of μ, δ and κ opioid receptors in the lower brainstem of the cat has been determined autoradiographically by studying the binding of tritiated [D-Ala 2,MePhe 4,Glyol 5][tyrosyl-3,5- 3H]enkephalin (DAGO), [D-Pen 2,D-Pen 5][tyrosyl-3,5-(n)- 3H]enkephalin (DPDPE) and [9- 3H]ethylketazocine (EKC), respectively. General opiate receptor binding was established using [ 3H]naloxone (NX). High densities of [ 3H]NX and DAGO binding sites were found most prominently in the nucleus tractus solitarii. There was no DPDPE and very weak EKC binding within this nucleus, although both these ligands bound to the cerebellum. The effect of unilateral vagotomy on receptor density was examined. Sectioning the cervical vagus had no effect on the density of μ receptors in the brainstem. Sectioning the vagus, accompanied by nodose ganglion excision, led to a marked depletion of μ receptors which was restricted to dorsal and medial regions of the ipsilateral nucleus tractus solitarii at, and rostral to, the obex. These results suggest that μ opiate receptors are located presynaptically on vagal afferents terminating within a restricted region of the nucleus tractus solitarii.

Effect of unilateral thoracic vagotomy on histamine-stimulated acid secretion in man

In the past, the effect of vagotomy on gastric secretion has been considered to be an “all or none” effect [2]. In fact, it has been reported that division of 75% of the vagal fibers at the level of the esophageal hiatus does not affect gastric secretion 151. However, recent studies have demonstrated a segmental vagal innervation of the canine stomach [4]. Although unilateral vagotomy at the cervical level in the dog did not affect acid secretion, when the separation was at the level of the diaphragm, insulin-stimulated acid secretion was reduced by 50% [6]. Furthermore, unilateral vagotomy has significantly reduced basal secretion and the acid response to stimulation by pentagastrin, histamine, and insulin in the ferret PI. No comparable data concerning the effect of unilateral vagotomy in man are available. During the course of simple or extended pneumonectomy for carcinoma of the lung, it is occasionally necessary to cut a vagal trunk to insure complete lymphadenectomy. This prompted the study of the acid response to histamine stimulation in patients undergoing a thoracotomy for carcinoma of the lung.

Effect of Unilateral Vagotomy on Gastric Secretion in the Ferret

The effect of posterior unilateral, truncal (subdiaphragmatic) vagotomy on the gastric acid response to graded doses of pentagastrin, a maximal dose of histamine, and a maximal dose of insulin was evaluated in the chronic fistula ferret. Unilateral vagotomy markedly reduced the acid output to each of these agents as well as the basal acid output. Reduction in acid concentration consequent to unilateral vagotomy did not parallel the decrease in acid output. Although the maximal pentagastrin dose elicited a greater stimulation of acid output than the maximal dose of histamine in intact animals, peak acid outputs after unilateral vagotomy were similar following maximal pentagastrin, maximal histamine, or maximal insulin stimulation. These data support the hypothesis that the vagal system must be intact in the ferret in order to achieve a maximal pentagastrin response, a phenomenon present in man and the cat but not in the dog. Further, evidence is provided that the mode of pentagastrin stimulation is more dependent than histamine stimulation upon the cholinergic system or, alternatively, that the cholinergic system is more sensitive to pentagastrin. The observed reduction of the gastric acid response to insulin after unilateral vagotomy supports the notion of a segmental, vagal innervation of the parietal cell mass.

The effect of unilateral vagotomy on gastric secretion in the pylorus ligated rat.

The effect of unilateral vagotomy on gastric secretion in the pylorus ligated rat.