日照逆転に対するラット排卵時期の適応性について

抄録

Studies were made on the transient responses of rat ovulation and vaginal smear to the reversal of the daily lighting schedules. Two kinds of lighting schedule, which were reversal each another, were used. One of the lighting schedules was normal lighting schedule, coinciding with the solar day, in which fluoresent lamps were switched on at 5 a.m. and switched off at 7 p.m. The other was artificially reversed lighting schedule in which the lamps were switched on 7 p.m. and switch-ed off at 9 a.m. These lighting schedules were consisting of 14 hrs. of light and 10 hrs. of darkness and were automatically regulated by a time switch. The vaginal smear was taken twice daily at 9 a.m. and 7 p.m. The ovulation was examined by the discovery of ovulated ova in the ampulla of the oviduct.
The rats, which were exposed to the reversed lighting schedule and confirmed the synchronization of their vaginal smear to the lighting rhythm, were transfered into the condition of the normal lighting schedule at 7 p.m. of the each stage of their estrous cycle, and the shift of the time of ovulation after the transference was examined as well as the change of the vaginal smear.
The ovulation in the normal lighting schedule and in the reversal lighting schedule respectively take place between 1 and 2 a.m. and between 3 and 5 p.m. of the following darkness of the proestrous stage. The synchronization of the vaginal smear to the normal lighting rhythm is not recognizable within 4 days after the reversal, but confirmable within 8 to 16 days in almost all rats. The synchronizaton of the ovulation, on the other hand, is more readily achieved than that of the vaginal smear, by delay of the ovulation at the rate of 1-2 hrs. per day.