Effect of hypophysectomy and growth hormone on serum and antral gastrin levels in the rat.

The effects of hypophysectomy and subsequent replacement therapy with growth hormone on serum and antral gastrin levels was investigated in both fasted and nonfasted pair-fed rats. Hypophysectomy caused a 57% decrease in serum and 47% decrease in antral gastrin content in 18-hr fasted animals. In nonfasted animals, hypophysectomy resulted in a 42% fall in serum gastrin and a 76% fall in antral gastrin. Animals were given injections of growth hormone over a 10-day period, then fasted 16 to 18 hr before being killed. Doses of 100 to 200 mug per 100 g of body weight were ineffective, but a dose of 500 mug per 100 g was sufficient to restore completely serum gastrin levels to intact control values. In nofasted rats this same dose raised serum gastrin to intact levels and increased antral gastrin significantly over hypophysectomized levels, but did not increase it to control values. When given to pair-fed intact animals, growth hormone caused slight but not significant elevations in serum and antral gastrin. The effect of growth hormone on gastrin secretion and /or synthesis may be a significant physiological factor in the regulation of normal gastrointestinal function and growth.