Vasoactive intestinal peptide inhibits release of somatostatin from hypothalamus in vitro

The effect of vasoactive intestinal peptide (VIP) was studied on the release of somatostatin (SRIF) from slices of several regions of the rat brain in vitro. VIP induced a dose-dependent inhibition of SRIF release from mediobasal hypothalamic slices but did not interfere with SRIF release from preoptic area, amygdala or cortex. VIP inhibition had an apparent affinity: Kd = 6.8 +/- 3.9 x 10(-11) M. Secretin had a similar effect but at 600-fold higher concentrations (Kd secretin = 4.2 +/- 0.6 x 10(-8) M). Gucagon was ineffective in concentrations ranging from 10(-10) M to 10(-7) M. The data are consistent with a role of VIP in the hypothalamic control of growth hormone secretion.