ALTERATION OF NEONATAL RAT PAROTID GLAND ACINAR CELL PROLIFERATION BY GUANETHIDINE-INDUCED SYMPATHECTOMY

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Abstract
Newborn rats were injected with guanethidine sulfate (20 .mu.g/g body wt) every 48 h from 12 h after birth until day 14 (8 injections/animal). The guanethidine treatment resulted in an 86% absolute reduction in cell number in the superior cervical ganglia of 15 day old rats. The cells which remained after guanethidine treatment showed destruction of mitochondria and an extensive decrease in endoplasmic reticulum. Chemical sympathectomy with guanethidine induced a 3.1 h lengthening of the acinar cell generation cycle time (17.4 h to 20.5 h), resulting from a longer G1 period (6.9 h in the control group as compared to 10.5 h in the guanethidine-treated group), as well as a decrease in the mean percentage of [3H]thymidine-labeled acinar cells (22.3 .+-. 0.5% to 19.3 .+-. 0.5%) and mean acinar cell mitotic index (2.6 .+-. 0.2% to 2.1 .+-. 0.1%). A circadian rhythm existed in parotid gland acinar cell mitotic activity of 15 day old rats and the amplitude of the rhythm was reduced from 26.5% to 14.9% in guanethidine-treated rats. The diminution of sympathetic influence on the developing parotid gland apparently results in a slight, but significant alteration in acinar cell proliferation.