Ramaley J A
Proc Soc Exp Biol Med. 1975 Mar;148(3):762-4. doi: 10.3181/00379727-148-38626.
A daily rhythm of serum corticosterone persists in 31 day old immature female rats in which pseudopregnancy has been induced by means of 25 IU pregnant mare's serum gonadotrophin (PMS) given at 26 days of age. There is, in addition, a daily rhythm of progesterone in 31-day old controls with a rise during the day and a fall during the dark portion of the photoperiod. PMS-injected rats had a much higher level of progesterone but no rhythm.
在31日龄未成熟雌性大鼠中，通过在26日龄时注射25国际单位的孕马血清促性腺激素（PMS）诱导假孕，其血清皮质酮存在日节律。此外，31日龄对照组的孕酮也有日节律，在光周期的白天升高，黑夜降低。注射PMS的大鼠孕酮水平高得多，但没有节律。
