The time interval effect on two consecutive LHRH-TRH tests on adult female baboons.

To Clarify the relationship between the time interval and pituitary Luteinizing hormone (LH), Follicular stimulation hormone (FSH) and prolactin (PRL) secretion function under LHRH-TRH stimulation, 4 mature female baboons were used. Two consecutive LHRH (100μg)-TRH (250μg) stimulations with a 60min interval between them was carried out in the early follicular phase, late follicular phase and mid luteal phase in the same baboon in the first menstrual cycle, then carried out with a 120min interval between tests in the third menstrual cycle. The LH, FSH and PRL were measured by specific radioimmunoassay.The PRL maximum response to the first bolus of TRH was higher than maximum response to the second bolus of TRH. The PRL maximum response to the second TRH at a 120min interval was higher than the maximum response to the second TRH at a 60min interval. It seems that the TRH had the dominant effect on PRL releasing but not on PRL Priming.The maximum LH response to the second bolus of LHRH was higher than the maximum response to the first bolus of LHRH. The LH maximum response to the second bolus of LHRH at a 60min interval was greater than the maximum response at a 120 min interval in the follicular phase but it was the reverse in the luteal phase. The FSH response to the second LHRH was different from the LH response. The FSH maximum response to the second bolus of LHRH in 120min was greater than the maximum response to the second bolus of LHRH at a 60 min interval in all phases of menstrual cycle. It seems that the longer time interval does not favor the LH response or priming effect, but does favor the FSH in this study.