Although restraint stress accelerates colonic transit via a central corticotropin releasing factor (CRF), the precise mechanism still remains unclear. We tested the hypothesis that restraint stress and central CRF stimulate colonic motility and transit via a vagal pathway and 5-HT₃ receptors of the proximal colon in rats. ⁵¹Cr was injected via the catheter positioned in the proximal colon to measure colonic transit. The rats were subjected to a restraint stress for 90 min or received intracisternal (ic)-injection of CRF. Ninety minutes after the administration of ⁵¹Cr, the entire colon was removed and the geometric center (GC) was calculated. Four force transducers were sutured on the proximal, mid, and distal colon to record colonic motility. Restraint stress accelerated colonic transit (GC; 6.7±0.4, n=6), compared to non-restraint controls (GC; 5.1±0.2,n=6). Ic-injection of CRF (1.0 µg) also accelerated colonic transit (GC; 7.0±0.2, n=6), compared to saline-injected group (GC; 4.6±0.5, n=6). Restraint stress-induced acceleration of colonic transit was reduced by perivagal capsaicin treatment. Ic-injection of CRF antagonists (astressin; 10 µg) abolished restraint stress- induced acceleration of colonic transit. Stimulated colonic transit and motility induced by restraint stress and CRF were significantly reduced by the intraluminal administration of 5-HT₃ antagonists, ondansetron (5x10^-6 M; 1 ml) into the proximal colon. It is suggested that restraint stress stimulates colonic motility via central corticotropin-releasing factor and peripheral 5-HT₃ receptors in conscious rats.