Ventromedial hypothalamic lesions increase gastrointestinal DNA synthesis through vagus nerve in rats.

Abstract

It was recently reported that ventromedial hypothalamic (VMH) lesions produced an increase in gastrointestinal DNA content in rats. In the present study, the mechanism of this alteration was examined. The DNA content and synthesis after VMH lesioning in rat gastrointestinal tracts were determined. Total content of DNA in stomach and small intestine began to increase at 3 days and continued to increase for 7 days, whereas DNA content in the large intestine began to increase at 3 days and maintained the same level until 7 days after VMH lesioning. DNA synthesis of these organs increased and reached maximum at 3 days and then decreased to the initial level 7 days following the lesions. This increase in DNA content and synthesis in these organs was largely inhibited by bilateral subdiaphragmatic vagotomy or the administration of atropine, a cholinergic blocker, but not by the administration of anti-insulin antibody. VMH lesions induce cell proliferation in the rat gastrointestinal tract by the firing of vagus nerve activity mainly through the cholinergic receptor mechanism.