Comparative Study of Histological and Kinetic Variations of the Digestive Mucosa and Pancreatic Parenchyma after Hypophysectomy in the Rat

Abstract

Variations of the pancreatic parenchyma, the gastric mucosa and the intestinal mucosa were studied in adult male Wistar rats on day 8 and 15 after hypophysectomy. All results were compared with those obtained in pair-fed control rats. Hypophysectomy affected small intestine as well as gastric mucosa. Hypotrophy was observed on day 8 as most of the morphological parameters reached the maximal decrease. By contrast, hypoplasy occurred on day 15, when the labeling index (LI) decreased significantly. In the intestine, however, a decrease of the LI was observed only for the upper proliferative cells of the crypts. In the gastric mucosa, the LI was reduced only in the proliferative zone containing progenitor cells (isthmic region). Consequently, the cell differenciation is not similarly affected on all levels of the digestive tract.

Digestive System

“…The detailed morphological study of the small intestinal mucosa in the rat following hypophysectomy has shown a reduction in the height of the small intestinal villi associated with reduction in mitoses in the crypt epithelium. 359 The number of goblet cells was shown to fall particularly in the jejunum and the number of Paneth cells increase in the ileum. Examination of ultrastructure showed decreased height of the microvilli of absorptive cells and a lower number of intracytoplasmic organelles and ribosomes.…”

“…Although there was little or no change in peptic:parietal cell ratios, a significant decrease in cell volume and secretory activity of gastric glandular cells were demonstrated which suggested a widespread disturbance of synthesis and secretory mechanisms. 359 Atrophic changes in the chief cells were observed in rats treated for six months with high doses of omeprazole, an inhibitor of acid secretion. The findings were considered to represent disuse atrophy secondary to the inhibition of acid secretion.…”

“…Decreased cell proliferation can be seen following decreased food intake, parenteral nutrition, hypophysectomy, thyroidectomy or in bowl segments which have been surgically bypassed. 359,456,457 As adrenergic factors are important in the control of small intestinal epithelial cell division, drugs that alter α or β adrenoreceptor activity may influence the proliferative capacity of the epithelium. In mice, increased α 1 or β receptor stimulation by appropriate agonists (e.g.…”