Effects of reserpine on the incidence of 9,10-dimethyl-1,2-benzanthracene-induced tumors in pinealectomised and thymectomised rats.

After reserpine treatment the incidence of dimethyl-benzathrance-induced tumors was found to be significantly higher in pinealectomised rats than in intact or thymectomised ones. A very high rate of DMBA-leukemia was observed in immune deficient pinealectomised rats after reserpine administration. It is therefore suggested that the neuro-endocrine disturbances, due to removal of the pineal gland in the new-born animals, are latent and become evident after reserpine administration, as reflected in an increased tumor incidence.