Involvement of central noradrenergic pathways in the control of intestinal motility in rats

Small intestinal motility was monitored in conscious rats chronically fitted with intraparietal electrodes, the third and fourth weeks after intraperitoneal administration of saline (controls) or N-(2-chloro-ethyl)-N-ethyl-2-bromobenzylamine (DSP-4, 50 mg/kg), a noradrenergic neurotoxin. Norepinephrine concentrations determined 35 days later in the forebrain and the brainstem were dramatically reduced in DSP-4-treated rats. The frequency of intestinal cycles of motor activity observed after 15 h of fast was very irregular and significantly lower in DSP-4-treated rats. The disruption of the cyclic activity induced by feeding was uncomplete on the duodenum and significantly shorter on the jejunum after DSP-4 treatment. These data indicate that the central noradrenergic innervation plays an important role in the control of the small intestinal cyclic activity and its postprandial disruption.