Figure 1.

(a) Threshold of visceromotor response (VMR) determined by the distended balloon volume (mL) inducing apparent sustained abdominal muscle contractions. Demonstrable electromyogram (EMG) recording is depicted. The threshold of VMR was 0.4 mL in this rat. (b) Schematic representation of the experimental protocol. Grape seed extract (GSE) or vehicle was administered intragastrically once daily for 7 days. On the 8th day, GSE or vehicle was administered again, and 1 h later, surgical electrode implantation and insertion of a distension balloon into the distal colon were performed. The basal threshold of the VMR was analyzed 30 min after the surgery. The animals were then subjected to either WAS or sham stress for 1 h. The rats underwent this treatment, i.e., GSE or vehicle administration followed by a stress session, for 3 days. On the 11th day, the drug was administered and the analysis of the second threshold of VMR followed by the permeability test was conducted at 24 h after completing the last stress session. GSE, grape seed extract. VMR, visceromotor response, WAS, water avoidance stress.