gastrins and Hyperphagia

The lining of the intestinal tract is constantly renewed in a brisk but orderly fashion. Further acceleration of cell renewal is elicited by various stimuli, notably surgical shortening of the intestine and hyperphagia, which lead to prompt but persistent increases in mucosal mass. Progressive hypoplasia ensues when the small and large bowel are deprived of their normal contents, either by fasting (with or without parenteral nutrition) or by exclusion from intestinal continuity. All atrophic changes are reversed by refeeding or restoration of the normal anatomical disposition. Intestine responds to mucosal damage by regeneration from the crypts. Pancreatobiliary secretions mediate some of the tropic effects of chyme; systemic influences, both neurovascular and humoral, also play a part in the adaptive response of the gut.

Topics: Adaptation, Physiological; Adult; Animals; Cell Division; Colectomy; Colostomy; Female; Gastrins; Glucagon-Like Peptides; Humans; Hyperphagia; Hyperplasia; Hypertrophy; Ileum; Intestinal Diseases; Intestinal Mucosa; Intestines; Jejunum; Obesity; Parenteral Nutrition; Rats; Starvation

Somatostatin, gastrin-releasing peptide (GRP) and gastrin were measured in the stomach of rats with streptozotocin-induced diabetes, insulinoma-bearing rats and their respective controls. Rats injected with streptozotocin exhibited hyperphagia, insulinopenia and severe hyperglycemia. Stomach weights, and the concentrations and total amounts of GRP and gastrin in the stomach, were similar to nondiabetic control rats. The concentration of somatostatin in the stomach of diabetic rats was 25% greater, but the total stomach content of somatostatin was similar to that of control rats. Insulinoma-bearing rats exhibited hyperphagia, hyperinsulinemia and hypoglycemia. Concentrations of GRP and gastrin in the stomach were 72% and 19% lower, respectively, than in control rats. Despite 45% greater stomach weight, the total stomach content of GRP was 61% lower. Stomach concentrations of somatostatin, and total stomach contents of somatostatin and gastrin, were similar in insulinoma-bearing and control rats. The results demonstrate abnormalities in the stomach concentrations of regulatory peptides in rats with diabetes and insulinoma. These abnormalities are not attributable to changes in food intake alone, suggesting specific effects of these metabolic diseases on gastric regulatory peptides and gastric function.

Topics: Animals; Blood Glucose; Diabetes Mellitus, Experimental; Gastric Mucosa; Gastrin-Releasing Peptide; Gastrins; Hyperphagia; Insulin; Insulinoma; Male; Organ Size; Peptides; Rats; Rats, Inbred Strains; Somatostatin; Stomach

Basal plasma gastrin levels were significantly higher in obese rats induced by ventromedial hypothalamic lesions (VMH rats) than in sham-operated controls. Gastrin secretion in response to insulin hypoglycemia and a liquid diet load was higher in VMH rats than in controls. The antral gastrin concentration was also elevated in VMH rats. Pair-fed rats with VMH lesions showed increased gastrin secretion as did the non-pair-fed group. These results show that gastrointestinal hormone secretions as well as pancreatic endocrine function are abnormal in obese rats with VMH lesions. Increased gastrin secretion is probably induced by factors other then hyperphagia, such as disturbance of the autonomic nervous system due to the VMH lesions.

Topics: Animals; Blood Glucose; Gastrins; Humans; Hyperphagia; Insulin; Insulin Secretion; Male; Obesity; Rats; Rats, Inbred Strains; Vagus Nerve; Ventromedial Hypothalamic Nucleus