Twenty-four-hour basal and repetitive pentagastrin-stimulated gastric acid secretion in normal and sham-operated rats and in rats after gonadectomy or treatment with estradiol or testosterone.

BACKGROUND

Studies in different species have suggested, but not established, that sex hormones influence gastric acid secretion. We studied how acid output is affected by the sex hormones estradiol or testosterone in vivo and in vitro.

METHODS

In gastric fistula rats that were normal, sham-operated, neonatally gonadectomized, or treated with estradiol or testosterone, 24-h basal and pentagastrin-stimulated acid secretion was measured. The in vitro effects of estradiol and testosterone on histamine-induced aminopyrine accumulation in isolated parietal cells were also determined.

RESULTS

Basal acid output was similar in the two sexes, but stimulated secretion was significantly higher (34%; P < 0.01) in males. Ovariectomy did not influence acid output, whereas orchidectomy reduced basal (18%; NS) and stimulated 24-h secretion (P < 0.01). Estradiol decreased (23%; NS) the 24-h basal output in females but not in males. Estradiol suppressed stimulated secretion in females (29%, P < 0.01) and males (42%, P < 0.01) during the day. At night the stimulated secretion increased in both females (17%, NS) and males (32%, P < 0.05). A similar pattern was found when rats were treated with testosterone. In vitro, estradiol and testosterone reduced histamine-stimulated aminopyrine accumulation in both female and male isolated parietal cells.

CONCLUSIONS

Estradiol and testosterone both appear to influence gastric secretion in rats, and their action differs between day and night, between the sexes, and between basal and stimulated secretion.