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In rats anesthetized with urethane, the effects of distention of the stomach upon cecal motility and neural mechanisms which generate this effect were studied. Cecal motility was inhibited which generate this effect were studied. Cecal motility was inhibited when the pars glandularis of the stomach was distended by pressure ranging from 25 to 30 cm H2O. This inhibitory reflex was not affected by bilateral cervical vagotomy, but completely abolished following bilateral severance of the greater splanchnic nerves or after intravenous administration of guanethidine. After transection of the spinal cord at the level of the 5th thoracic segment the inhibitory reflex remained intact, but was abolished following pithing of the 6th thoracic segment and below. It may be concluded that the afferent and efferent path of the gastrocecal inhibitory reflex mainly pass through the greater splanchnic nerves and the reflex center is located in thoracic segments caudal to the 6th thoracic segment.

The effects of electrical stimulation of the satiety and feeding centers (SC, FC) on gastric, cecal and rectal motility were studied in rats anesthetized with urethane. Each center produced excitatory, inhibitory and biphasic responses in these organs. Cecal and rectal responses to stimulation of SC or FC were usually the opposite of the gastric response; for example, the gastric response was excitatory, whereas cecal and rectal responses were inhibitory. Gastric and cecal excitatory responses were abolished by vagotomy and the rectal response by severance of parasympathetic branches of the pudendal plexus (PSB). Gastric and ceca inhibitory responses were fairly depressed by vagotomy and abolished by successive splanchnicotomy, while the rectal inhibitory response was abolished by severance of inferior mesenteric nerves (IMN) and PSB. It was concluded that the satiety and feeding centers modulate not only gastric motility but also cecal and rectal motility, and that the excitatory response is conveyed through vagus nerves to the stomach and cecum and through PSB to the rectum. The inhibitory response is mediated mainly through vagus nerves, partially through splanchnic nerves to the stomach and cecum, and through IMN and PSB to the rectum. The characteristics of efferent terminal neurons eliciting excitatory and inhibitory responses were studied pharmacologically.