The sympathetic nervous system in the intestinal mucosa releases
norepinephrine (an a2 antagonist) and so inhibits electrolyte secretion and stimulates absorption. Sympathectomy, whether chemical or surgical, leads to diarrhea, at least transiently. Chronic diabetics with autonomic neuropathy sometimes develop persistent diarrhea that is associated with degeneration of adrenergic nerve fibers to the gut. Somatostatin and endogenous enkephalins are also antisecretory.
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