Modification of cyclocytidine-induced changes in [3H]thymidine incorporation and weight of parotid gland by partial sialoadenectomy.

Cyclocytidine (CC), a potent antitumor agent, caused a 2.3- to 5.0-fold increase in 3H]thymidine uptake of rat parotid gland after 3 days of daily administration of 500 mg/kg body wt. Gland weight also showed a 47-67% increase from that of controls. Ablation of the submandibular-sublingual glands prior to initiation of the CC regimen prevented the usual CC-induced increase in 3H]thymidine uptake, but did not inhibit the increase in gland size. It is postulated that CC-induced parotid hyperplasia requires an initial release of growth factors from the submandibular gland; however, enlargement of the parotid gland by CC is independent of such factors.