[Gastric mucosal lesions in rats induced by the communication box paradigm: experimental conditions, endoscopic observation, and effect of vagotomy].

A communication box paradigm which can eliminate the influence of the physical noxious stimuli such as electrical foot-shock from the conditioned emotional stimuli has recently been developed for producing gastric mucosal lesions (GML) in mice. In this situation, the unshocked animals (NE group) were exposed to affective stimuli such as visual, auditory and olfactory sensations from the shocked conspecifics (E group). The present study was conducted to investigate an experimental procedure that can be applied to rats. When the communication box paradigm was applied to rats, the incidence of GML was very low: E group (38%) and NE group (13%). Marked augmentation of the incidence of GML was obtained in both E and NE groups by reserpine pretreatment at the dose of 1 mg/kg which did not produce GML. Various kinds of GML were defined endoscopically using a narrow fibre scope. The manifestation of the GML in both E and NE groups was completely suppressed by vagotomy, whereas pyloroplasty was ineffective. The procedure for eliciting GML in rats was established by a combination of the communication box paradigm with reserpine pretreatment. The endoscopic technique may provide a clue for investigating the time-dependent healing process of GML, especially for evaluating the therapeutic effect of a drug.