Abstract: Objective To observe the effect of gut protease activity on visceral hypersensitivity in rats with acute restraint stress.
Methods Sprague-Dawley rats were given 30, 100 or 300 mg/kg camostat mesilate (CM), a protease inhibitor, or saline
intragastrically 30 min before acute restraint stress induced by wrapping the fore shoulders, upper forelimbs and thoracic
trunk for 2 h. Visceral perception of the rats was quantified as the visceral motor response with an electromyography, and the
rectal mucosa and feces protease activity and spinal c-fos expression were measured. Results CM dose-dependently reduced
visceral sensitization elicited by rectal distension, but these doses did not completely inhibit stress-induced visceral
sensitization. In normal rats, c-fos expression was found mainly in the superal spinal cord dorsal horn, and after the
administration the CM, c-fos-positive cells decreased significantly in all dose groups (P<0.05). In 30 mg/kg CM group, fecal and
rectal mucosal protease activity significantly decreased as compared with that in the stress group (P<0.05), and as CM dose
increased to 100 and 300 mg/kg, the protease activity decreased even further (P<0.01). Conclusion The gut protease is involved
in acute stress-induced visceral hypersensitivity, and CM can lower the visceral sensitivity and spinal c-fos expression in rats.