Protection by zinc sulphate against reserpine-induced ulceration and other gastric effects in the rat

Anti-ulcer Activity of a Slow-release Zinc Complex, Zinc Monoglycerolate (Glyzinc)

A slow-release zinc complex, zinc monoglycerolate (ZMG) was examined for its potential gastroprotective activity in various gastric ulcer models. These models comprised (a) oral or parenteral nonsteroidal anti-inflammatory drugs (NSAIDs) given to rats whose gastrointestinal mucosa was pre-sensitized by prior development of arthritis, oleyl alcohol-induced inflammation and cold exposure, (b) oral ethanol (12·5−100%) with and without added 4% HCl, (c) intraperitoneal reserpine (5 mg kg−1) in arthritic and normal rats and in normal mice, (d) oral NSAIDs given to mice in which acid and pepsin production was stimulated by co-administration of intraperitoneal bethanechol chloride (5 mg kg−1) to enhance ulcer development, and (e) NSAIDs given to carrageenan-inflamed rats to determine effects of ZMG on paw inflammation. In these models, ZMG given orally was effective in preventing development of gastric lesions, except with propionic acid NSAIDs; the effective doses being apparently dependent on the severity of the mucosal injury. In many of the models ZMG was superior to zinc sulphate and other zinc salts or metal ion complexes investigated but was slightly more effective or equipotent compared with zinc acexamate. ZMG did not impair the anti-oedemic effects of NSAIDs. ZMG is thus an effective agent in preventing ulcer development in a wide range of model systems and may be more effective than zinc salts because of the controlled slow-release of zinc from the complex.

Zinc sulphate reduces activity-stress gastric lesions in rats

Daily i.p. injections of zinc sulphate significantly reduced the frequency and severity of activity-stress gastric lesions in rats in a dose-related fashion. These lesions are believed to be of a non-acid etiology and respond primarily to centrally-acting agents. The present results suggest that some local factors contribute to activity-stress gastric damage.

The inhibition of ischemic lesions of the rat gastric mucosa by a novel serotonin-antagonist: a light and electron microscopic study

Two methods that provoke severe lesions in the rat gastric wall were used to study the pathologic action of serotonin. In a first group of rats 1 mg/kg of compound 48/80 was injected IV. The lethal shock that follows within about 30 minutes was prevented by subcutaneous administration of a H1- antagonist. This treatment did not suppress the gastric gland activity, in particular the gastric secretion, and resulted in time-related lesions situated in the gastric corpus and to a lesser extent in the antrum. In a second group of rats similar lesions were induced by slow infusion of 30 μg/kg/min serotonin into the femoral vein.

The earliest observed light microscopic events concerned mucosal vessel appearance. Most of the vessels were heavily dilated and engorged with blood cells. The most important ultrastructural changes were seen in the various epithelial cells. These were characterized by an early disappearance of intramitochondrial granular deposits. In a later stage progressive necrosis of the epithelial cells was observed. Lesions evolving from focal edematous erosions into deep necrotic and hemorrhagic wounds were found throughout the whole gastric wall. These final severe lesions were attributed to a local vascular congestion which led to cellular ischemia and a consequent energy deficiency of the mucosal cells.

When rats were orally pretreated with the novel serotonin-antagonist R 41 468 at a dose of 0.63 mg/kg, the light and electron microscopic picture was almost completely comparable to that of unchallenged animals. This indi cates that R 41 468 is a potent antagonist of peripheral venoconstriction induced by infused exogenous serotonin as well as by released endogenous serotonin.

The influence of cimetidine, a histamine H2-receptor antagonist, on the gastric effects of reserpine in rats

The effects of graded doses of cimetidine on both resting and reserpine-evoked gastric acid secretion were examined in relation to their influence on reserpine-induced ulceration, mast cell degranulation and mucosal microcirculatory changes in rat stomachs. Cimetidine 10 mg/kg or above reduced resting or reserpine-provoked gastric acid secretion as well as rumenal and glandular ulceration. However, non-acid-inhibiting doses, 5 mg/kg or below, continued to prevent glandular ulceration. Reserpine-evoked gastric glandular mucosal mast cell degranulation was unaffected by both acid-inhibiting and non-acid-inhibiting doses of cimetidine which dose-dependently blocked the superficial glandular mucosal microcirculatory volume changes. These results suggest that cimetidine prevents reserpine-induced glandular ulceration largely by blocking the ulcerogenic effect of histamine H2-receptor-mediated mucosal microcirculatory congestion, in contrast to antagonising rumenal lesions through acid inhibition; they also support the idea tha reserpine may release histamine mainly from the glandular mucosal mast cells. The possibility of another antiulcer mechanism, due to cytoprotection, is discussed.