Effects of Morphine on Gastric Ulceration, Barrier Mucus and Acid Secretion in Pylorus-Ligated Rats

Abstract

The effects of intraperitoneal (IP) or intracerebroventricular (ICV) administration of morphine on acid and pepsin secretion, gastric ulceration and gastric bound mucoproteins were investigated in pylorus-ligated rats. Morphine, administered IP, produced a dose-dependent inhibition of the gastric secretion volume, acidity, pepsin output and bound mucoproteins. By contrast, the effect of morphine on gastric ulcers was not dose-dependent: a significant increase in gastric lesions was obtained with morphine 5 mg/kg IP. Naloxone IP prevented the effects of morphine on gastric secretory volume, acidity and pepsin output, but not on gastric mucus and ulcer score. ICV administration of morphine induced a dose-dependent inhibition of secretory volume, acidity and ulcer score, whereas no modification of gastric mucus was observed. Naloxone ICV prevented the effects of ICV morphine. Overall results suggest that morphine inhibits gastric secretion through both central and peripheral opioid receptors, whereas the inhibitory effect of morphine on bound mucus appears to be exerted on mucus synthesis through peripheral opioid receptors. This inhibitory effect on barrier mucus accounts at least in part for the gastric ulcerogenic action of morphine.

Immunohistochemical characterization of neurons and neuronal processes in the dorsal vagal nucleus of the pig

“…Evidence indicating the involvement of opioid transmission to DMX, as a component of the dorsal vagal complex, originating from neurons of the NTS, amygdala or periaqueductal gray (Morilak et al 1989, Pickel et al 1989, Maley 1996, Farkas et al 1997, Giraudo et al 1998, Liubashina et al 2000 additionally support the functional significance of LENK related transmission in porcine DMX. In fact, activation of central opioid receptors have been shown to induce gastric relaxation (Burks et al 1987, Gue et al 1989, decrease gastric acid secretion (Del Tacca et al 1987) and increase feeding (Giraudo et al 1998). Identification of the close spatial relationship between LENK-IR processes and the preganglionic parasympathetic cell bodies shed light on its possible regulatory function in the porcine DMX.…”

Mechanisms of Protection by Omeprazole against Experimental Gastric Mucosal Damage in Rats

“…The measurement of mucus levels bound to the epithelial surface was performed according to the method of Come et al [17], as reported by Del Tacca et al [18]. Briefly, the glandular portion of the stomach was excised and immersed for 2 h in 0.1% Alcian blue in a 0.…”

“…Assessment of gastric acid secretion was carried out on pylorusligated rats, as previously reported by Del Tacca et al [18], with minor modifications.…”

Neuroinflammatory reactions in experimental gastric ulcer: Target for mucosal protection

“…Both central and peripheral effects may be involved in gastroprotective action of opioids against stress-or pylorus-ligation-induced mucosallesions [15,24,25]. However, gastric acid secretion is involved in the pathomechanism of both ulcer models.…”

“…However, gastric acid secretion is involved in the pathomechanism of both ulcer models. Since opioids exert inhibitory activity on gastric acid secretion injected either intracerebroventricularly (icv) or peripherally [24,26], the question was raisedwhether the antiulcer activity of opioids following icv administration is due to their antisecretory activity or whether their gastroprotective effect is independent of their antisecretory property. Therefore, in the present experimental series, we examined how opioids influence gastric lesions following icv administration in anulcermodel, where gastric acid secretion is not involved in the development of gastric mucosal lesions.…”