Vasoactive intestinal peptide is a local regulator of adrenocortical function

Area of Science:

• Endocrinology
• Neuroendocrinology

Background:

• Vasoactive intestinal peptide (VIP) presence in adrenal nerve terminals is known.
• Its specific function in the adrenal gland, particularly the zona glomerulosa, remains unclear.

Purpose of the Study:

• To investigate the physiological role of VIP in the rat adrenal gland.
• To determine VIP's effects on adrenal vasculature and hormone secretion.
• To explore the regulation of adrenal VIP by electrolyte balance.

Main Methods:

• Intact perfused rat adrenal preparation.
• Measurement of aldosterone and corticosterone secretion.
• Receptor binding studies.
• Dietary manipulation (low/high sodium) and splanchnic nerve section.

Main Results:

• VIP acts as a vasodilator in the adrenal gland.
• VIP stimulates both aldosterone and corticosterone secretion, with aldosterone effects potentially mediated by catecholamines.
• A low sodium diet significantly enhances the aldosterone response to VIP and increases VIP receptor density in the zona glomerulosa.
• Low sodium diet increases adrenal VIP content, while high sodium decreases it; splanchnic nerve section has no effect.

Conclusions:

• Adrenal VIP plays a crucial role in regulating zona glomerulosa function.
• VIP's function is particularly important in adapting to changes in electrolyte balance.
• VIP signaling in the adrenal gland is modulated by sodium intake.