[Morbidity and mortality rate from tumors and other causes in female rats under different light regime]

The influence of different light regimes (constant light--LL; constant darkness--DD; standard light regime--LD, 12 hours light/12 hours darkness; natural lightening of the North-West of Russia--NL) on the dynamics of life's morbidity rate, spontaneous tumorigenesis and frequency of some kinds of non-tumor pathology revealed at the post-mortem examination of female rats was studied. It was found out that the maintenance of animals at LL and NL conditions led to the increase of the number of infectious diseases, substantially faster development of spontaneous tumors (2,9 and 3,3 diseases per one rat, respectively) and the increase of non-tumor diseases in comparison with the animals kept at LD (standard light) regime (1,72 diseases per one rat). Light deprivation (DD) led to substantial reduction of development of new growth, of non-tumor and infectious diseases (1,06 diseases per one rat) in comparison with the similar parameters in standard light regime.