[Effect of serotonin on the viability of rats with transplanted glioblastoma multiforme]

Mongrel adult albino female rats with multiform glioblastoma transplanted to the right cerebellar hemisphere were given subcutaneous injections of 8 mg/kg of a serotonin-creatine sulphate solution beginning with the 3rd and to the 28th postoperative days. Rats with a tumor inoculated at the same periods and given injections of a physiological saline solution served as controls. The injection of serotonin leads to a significant increase in the survival of rats by 20% as compared to the survival of rats in the control group, but practically has no effect on the life span of sick animals. Consequently, serotonin either produces an antineoplastic effect in which case the animals do not contract the disease, or it has no effect on the tumor so that the animals die of the developing tumor. Study of the tryptophan content in the neoplasm and the 5-OIAA content in urine provides evidence of a disturbed serotonin synthesis and metabolism in these neoplasms.