Gastric acid secretion, serum gastrin and parietal cell histology in rat hyperthyroidism

Abstract

Experimental hyperthyroidism was produced in rats by thyroxin injection, and changes in gastric acid secretion and serum gastrin level were determined to analyze the relation between these changes and hyperthyroidism. Administration of thyroxin to two groups of rats-20 micrograms per 100 g of body weight for 20 days and 75 micrograms for 7 days-brought about significant increases in serum T3 level, gastric pH and serum gastrin level. An increase in gastric pH took place later than that in serum T3 level; this time lag implies that a decrease in acid secretion was not caused by an direct effect of thyroxin on the parietal cell but by its secondary effect. In the T4-injected rats with decreased gastric acid secretion, the parietal cell remained normal in form and succinic dehydrogenase activity was also normal. The electron microscopical observations showed nothing abnormal in the parietal cells. These findings suggest that a decrease in acid secretion was not due to any structural changes in the gastric mucosa but to functional suppression. The serum gastrin level rose in correlation with an increase in gastric pH and fell by HCl administration to the stomach. Feedback inhibition by pH remained in the G cell.

Effect of thyroxine and carbimazole treatments on basal and histamine stimulated gastric acid secretion in the common African Toad (Bufo regularis).

“…The relationship between thyroid hormones and its altered states on gastric acid secretion has been studied in several animal species and human (Akiyama et al, 1982;Kazuhiko et al, 2006). The reduced secretion in carbimazole treatment and increased secretion in tyrosine treatment is in agreement with the studies on rats (Akiyama et al, 1982;Adeniyi and Olowookorun, 1990); in human subjects (Kazuhiko et al, 2006;Fatemeh and Saleh, 2012). Adeniyi and Olowookorun (1990) suggested that thyroid hormones regulate basal and secretagogue stimulated acid secretion via their effects on parietal cell mass (Adeniyi and Olowookorun, 1989).…”

“…There is evidence that they also affect gastric acid secretion . Akiyama et al (1982) found out that the administration of thyroxine into rats led to significant increases in serum T 3 level, gastric pH (reduced acid secretion) and serum gastrin level. Adeniyi and Olowookorun observed that chronic administration of thyroxine increased parietal cell mass, as well as basal acid secretion and histamine-stimulated acid secretion (Adeniyi and Olowookorun, 1989), mice also show the same trend (Olaleye and Elegbe, 2005).…”