[The sex and corticosteroid hormones of rats selected for estrous-cycle reaction to constant illumination].

Two substrains of rats selected for the high (ESTH) and low (ESTL) ability to develop permanent oestrus under constant illumination were produced. The concentration of estradiol, testosterone in blood and 11-OCS in blood and adrenals was studied in rats of the 29 th generation under normal day (14L : 10D) and constant illumination (CL). The concentration of estradiol in blood of control rats in proestrus was 61.6 +/- 4.1 pg/ml and did not differ from substrain ESTH (59.6 +/- 4.5 pg/ml) and ESTL (58.8 +/- 4.8 pg/ml); in oestrus, the minimal concentration of estradiol was noted in control-(46.5 +/- 3.1 pg/ml), maximal one-in rats of substrain ESTL (63.3 +/- 6.2 pg/ml), in ESTH-55.8 +/- 1.7 pg/ml. The maintenance of rats in condition of CL brought about the tendency to decrease the level of estradiol in blood of rats selected in proestrus and to increase it in oestrus in comparison to control. The level of testosterone in blood of control rats in proestrus-oestrus changed in parallel to concentration of estradiol. The concentration of testosterone in blood of selected rats was higher in proestrus-oestrus as compared to control. In condition of CL, the testosterone level in proestrus did not differ from control, in oestrus it was higher than in control. The level of 11-OCS in adrenals of selected substrain was higher than in control as well in condition of 14L : 10D as in CL. The exception was substrain ESTH-in proestrus the concentration of 11-OCS in condition of CL was lower than in control. CL drastically changed direction of cyclic shifts in level of 11-OCS from higher value in proestrus under condition of 14L : 10D to low one in condition of CL. The fluctuation of 11-OCS level in blood in groups of experimental rats usually was parallel to that in adrenals.