INFLUENCE OF A CHRONIC ENVIRONMENTAL-STRESS ON INCIDENCE OF METHYLCHOLANTHRENE-INDUCED TUMORS

  • 1 January 1977
    • journal article
    • research article
    • Vol. 37  (11) , 3939-3944
Abstract
The influence of a chronic environmental stress, living in a 2.degree. C environment, on the incidence of methylcholanthrene-induced tumors in albino female Simonsen rats, a Sprague-Dawley-derived strain, was studied. The results indicated that the metabolic rate was doubled for rats kept at 2.degree. C, compared with those kept at 25.degree. C. Exposure to 2.degree. C for life, with no treatment, reduced median life expectancy to 560 days compared with 686 days for rats dept at 25.degree. C. Transfer to a 2.degree. C environment after 250 days at 25.degree. C reduced the incidence of spontaneous tumors, while transfer to 25.degree. C after 250 days at 2.degree. C increased the incidence of tumors compared to that for rats always kept at 25.degree. C . Exposure to an environmental temperature of 2.degree. C immediately following a carcinogenic stimulus (3-methylcholanthrene, 2 mg s.c.) significantly reduced the incidence of tumors compared to that in rats kept at 25.degree. C but did not change tumor induction time. The reduced tumor incidence may have resulted from inhibition of carcinogenic transformation by chronic stress. The survival time of rats with 3-methylcholanthrene-induced tumors was not significantly less in a 2.degree. C environment than at 25.degree. C.