Inhibitory Effect of Hypothalamic Lesions on Liver Tumor Induction by Af-2-Fluorenylacetamide in Male Rats1

Bilateral electrolytic lesions were placed in the median eminence area of the hypothalamus in 12-week-old male Wistar rats. Sham-operated and untreated control rats were also included. Two weeks later, one-half of them were given 0.03% rV-2-fluorenylacetamide incorporated into the diet for 16 weeks with adequate resting periods in between. The animals were killed 34 weeks after the last carcinogen feeding. The results show that lesions in the hypothalamus effectively inhibited liver tumor forma tion (0 of 16, 0%). In contrast, the incidence of hepatocellular carcinomas in sham-operated rats was 38.5% (5 of 13), and that of untreated controls was 42.9% (6 of 14). No tumors developed in rats fed diet without carcinogen. Testicular atrophy, inactive thyroid glands, and shorter nasoanal lengths were observed in rats with lesions in the hypothalamus irrespective of carcinogen treatment. It is apparent from these data that lesions in the median eminence area of the hypothalamus inhibit the induction of liver carcinogenesis with N-2-fluorenylacetamide in male rats.