Adrenalectomy abolishes hypergravity-induced gastric acid hyposecretion

Area of Science:

• Aerospace Medicine
• Gastroenterology
• Physiology

Background:

• High gravitational forces (+Gz) encountered by jet pilots induce physiological stress.
• While cardiovascular and cerebral effects of hypergravity are studied, gastrointestinal responses remain less understood.
• Previous research indicated reduced gastric secretion after acute hypergravity exposure.

Purpose of the Study:

• To investigate the role of adrenalectomy in modulating gastric acid secretion and plasma gastrin levels in rats exposed to hypergravity.
• To determine if adrenal glands are necessary for hypergravity-induced changes in gastric function.

Main Methods:

• Male Sprague-Dawley rats underwent adrenalectomy or sham operation.
• Rats were exposed to +10Gz for 3 minutes, repeated three times.
• Gastric juice and blood samples were analyzed for volume, acidity, and plasma gastrin levels.

Main Results:

• In sham-operated rats, +10Gz exposure significantly reduced gastric juice volume and acidity.
• Adrenalectomized rats exposed to hypergravity showed no significant changes in gastric juice volume or acidity compared to non-exposed controls.
• Hypergravity exposure did not affect gastrin levels in either group, but adrenalectomy abolished the acid hyposecretion response.

Conclusions:

• The adrenal glands play a critical role in mediating gastric acid hyposecretion following acute hypergravity exposure.
• Adrenalectomy effectively prevents the reduction in gastric acid secretion observed after +Gz exposure.
• These findings highlight the involvement of the adrenal system in the gastrointestinal response to extreme gravitational stress.