Neurally mediated increase in mitosis and DNA of rat parotid with increase in bulk of diet.

A transient burst of mitosis was induced in rat parotid gland 2 days after change from a diet of solid chow only to one consisting of 50% inert cellulose and 50% solid chow (bulk diet). Mitosis was thus induced when glandular activity was changed from normal levels (solid chow) to levels greater than normal (bulk diet). Elimination of either autonomic pathway inhibited the mitotic response, but elimination of the parasympathetic had the greater inhibitory influence. The burst of mitosis induced by bulk diet was followed by increases in total DNA (16%), RNA (24%) and weight (27%) of the gland 2 wk after the dietary change. These changes did not occur when both autonomic pathways were, or only the parasympathetic was, removed immediately prior to the dietary change. Effects of sympathectomy were less pronounced. The parasympathetic innervation has the principal role in regulation of mitosis, cell number and size, and nucleic acid content when glandular activity is increased above normal by physiological means.