Abstract: Substance P(SP)and vasoactive intestinal peptide(VIP)levels in blood and all layers of initial part of ileum in rats were measured by radioimmunoassays(RIA)in order to explore the mechanism of cool stress. SP levels in ileum of cool stress didn't change while the VIP levels in ileum of cool stress were significantly lower than the controls groups(P<0.05). SP levels in blood of cool stress were significantly higher(P<0.01)while the VIP levels in blood of cool stress were significantly lower than the controls groups(P<0.01). The results shows that changes of SP and VIP levels in the initial part ileum and blood of cool stress may be related to the gastrointestinal motility disorders presented in cool stress rats.

Key words: stress|substance P(SP)|vasoactive intestinal peptide(VIP)