Circadian rhythms of RNA, DNA and protein in the rat thyroid, adrenal and testis in chronic pesticide exposure. III. Effects of the insecticides (dichlorvos and trichlorphon).

Chronic exposure of the rats to Trichlorphon (10 ppm/day, over a time span of 90 days) leads to marked changes in the time structure of the thyroid and the adrenal, e.g. the loss of the circadian rhythms as a group phenomenon in thyroid DNA and protein and adrenal RNA content, phase alterations in thyroid RNA and adrenal DNA rhythms, marked decrease in amplitude of the adrenal DNA and protein rhythms. Ninety days of exposure to Dichlorvos (5 ppm/day) leads to phase alterations, without a change in the time-qualified mean (mesor), of the circadian rhythms in DNA, RNA and protein content and marked decrease in amplitude of the DNA rhythm, in the thyroid and the adrenal. In the testis, there is no alterations of the rhythms studied. The phase alterations encountered in this study are different in extent and also in direction, between and within the organs, indicating an external and internal desynchronization of metabolic and cell proliferative functions. The variability of the acrophases obtained by the separate analysis of each of the three days of study may suggest free-running rhythms.