The Time Interval Effect on Two Consecutive LHRH-TRH Tests on Adult Female Baboons

Transcription

1 Endocrinol. Japon. 1985, 32 (4), The Time Interval Effect on Two Consecutive LHRH-TRH Tests on Adult Female Baboons JINU-HAUNG SU, TAKESHI ASO*, MASATERU MATSUOKA*, KATSUYUKI HORIE* AND TOSHIO NISHIMURA* Department of Obstetrics and Gynecology, Kaohsiung Medical colledge, Taiwan, R. O. C. *Department of obstetrics and Gynecology, Kyoto University, Kyoto, Japan Abstract 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 (100ƒÊg)-TRH (250ƒÊg) 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. The stimulatory effect of the luteinizing hormone releasing hormone (LHRH), given in various doses for a short interval or by constant infusion, on the gonadotropin synthesis and release by the pituitary have been studied extensively in animals and human beings (Rebar et al., 1973; Ferin Received August 17, 1984 et al., 1978; Bremner et al., 1974; Rommler et al., 1978; Pinto et al., 1979; Hoff et al., 1979). Rat (Castro-Vazquez et al., 1975), monkey (Ferin et al., 1974), and women (Wang et al., 1976; Yen et al., 1976; Wentz et al., 1980; Kletzky et al., 1982; Takahashi et. al., 1984) are capable of responding to two consecutive LHRH stimulations at 60

2 456 SU et al. Endocrinol. Japon. August 1985 to 120min interval, That the response to the second injection of LHRH was markedly higher than the response to the first LHRH injection was reported by Yen et al. The second gonadotropin response was modified by Rommler et. al. by varying the first or the second LHRH dose at 120min intervals. Some data showed that the interval between the two LHRH injections might be a critical factor in determining the magnitude of the second response. There was no report on PRL response to two consecutive TRH stimulations, and how the time interval between the two TRH injections effects the PRL response is still unknown. We conducted present study in adult female baboons to find how the dose and the varying time interval between two consecutive LHRH-TRH injections can effect the LH, FSH and PRL response at different stages of the menstrual cycle. interval. Blood specimens for the assay of the LH, FSH and PRL were obtained by venipuncture every 15 to 30min for a total of 180 to 240min using heparinizing syringes. The plasma samples were stored at -20 Ž until analysis. All injections and blood drawings were conducted without anesthetics. Plasma LH and FSH were measured with the double antibody radioimmunoassays described by Su et al. (1980). The baboon's PRL was measured with a human kit (Daiichi Radio-isotope Ltd., Japan) described previously by Aso et al. (1979). Purified LH and FSH, standard and antisera were kindly donated by Niswender et al. (1971) and Hodgen et al. (1976). The intraassay coefficients of variation were 7.6% for LH, and 3.6% for FSH. Interassay coefficients of variation were 14.14% for LH and 8.32% for FSH. The intraassay and interassay coefficients of variation were 6.4% and 11.2% for the PRL, respectively. Student's t-tests was used for the statistical analysis. Results Materials and Methods Consecutive stimulation tests were carried out in four mature female baboons (Papio cynocephalus). Animals weighing between 12 to 16kg with a 28 to 33 days regular menstrual cycle were used in this study. They were housed in individual cages in a temperature and humidity controlled environment with a constant light and dark periods (12: 12h). They were fed on a standard monkey pellet food, supplemented daily with fresh fruits and vegetables. Water was available ad libitum. Other care and training of the baboons were same as in the previous report (Su et al., 1980, 1981). Each baboon received two intravenous injections combined with 100ƒÊg synthetic LHRH (Daiichi Pharmaceutical Company Tokyo, Japan) and 250ƒÊg TRH (Tanabe Pharmaceutical Company, Osaka, Japan) into the antecubital or the saphenous vein. Two consecutive stimulation tests were performed three times in the first control cycle with a 60min interval between them on the cyclic days 4 to 6, 9 to 12 and 22 to 26. The tests were repeated on the same baboon in the third menstrual cycle, but with a bolus of the second LHRH-TRH at a 120min The Symbols in this experiment are shown in Fig. 1. Peak 1 is the maximum response to the first bolus of LHRH-TRH. Peak 2-60 and peak are the maximum responses to the second bolus of LHRH-TRH. ƒ 1 is the maximum increase in the first bolus of LHRH-TRH. ƒ 2-60 and ƒ are the maximum increase in the second bolus of LHRH-TRH at minutes after the first bolus of LHRH-TRH. No side effect nor change in the menstrual cycle was found in any of the baboons during the experimental period or during LHRH-TRH stimulation tests. Peak 1 of PRL response was reached between 15 and 30min after the TRH administration in all baboons in different menstrual phases. Peak 1 was significantly higher (P<0.05) in the late follicular phase than the early follicular and luteal phase. The PRL response (Mean }S. D.) to TRH is shown in Fig. 2. Peak 1 was higher than peak 2, and peak 1 was much higher than peak Response ƒ 2-120

3 Vol.32, No.4 LH, FSH AND PRL SECRETION ON FEMALE BABOONS 457 Fig. 1. The symbols showing the result. Fig. 2. The Mean }S. E. response of PRL to consecutive LHRH-TRH tests.

4 458 SU et al. Endocrinol. Japon. August 1985 Fig. 3 The Mean }S. E. response of LH to consecutive LHRH-TRH tests. Fig. 4. The Mean }S. E. response of FSH to consecutive LHRH-TRH tests.

5 Vol.32, No.4 LH, FSH AND PRL SECRETION ON FEMALE BABOOSN 459 was also much higher than response ƒ 2-60 in all stages of the menstrual phase (Fig. 5), (P<0.03). The LH response to LHRH is shown in Fig. 3. Peak 1 or peak 2 of LH response was reached between 30-60min in each phase except for the late follicular phase. Peak 1 in the early follicular phase was lower than in the late follicular phase and the luteal phase. All responses for peak 2 were higher than for peak 1. The response follicular phase, but it was lower in the luteal phase, but it was not statistically significant (Fig. 5). The FSH response to LHRH is shown in Fig 4. Peak 1 and peak 2 of the response were reached in 60min after the LHRH bolus in all stages of the menstrual cycle. Peak 1 of the response in the early follicular phase was lower than in the late follicular phase and the luteal phase. Peak 1 was also much lower than peak 2 (P< 0.05). The response ƒ was higher than the in all stages of the menstrual cycle, but the difference is significant only in the luteal phase (P<0.01). Discussion We conducted this study with LHRH- TRH to evaluate the time interval effect on LH, FSH and PRL responses because McNeilly et al. (1974) reported that in both sexes the responses to the two releasing hormones were unaffected when they were given together. Also Su et. al. (1980) report- E.F. phase L.F. phase Luteal phase Fig. 5. The comparison of PRL, LH and FSH second increases? ƒ 2-60 and in early follicular phase, late follicular phase and luteal phase with 60 and 120min interval LHRH-TRH pulse.

6 460 SU et al. Endocrinol. Japon. August 1985 ed that these two releasing hormones were unaffected when they were given together in female baboons. Furthermore Kastin et. al. (1971) reported that the plasma prolactin level was also unaltered in men after the administration of synthetic LH releasing hormone. The result of the present study demonstrated that peak 1 of the LH and the FSH response was reached between 30 to 60min after LHRH administration. Peak 1 of the LH and the FSH response was higher in the late follicular and the luteal phase than in the early follicular phase. Peak 2 of the gonadotropin response to LHRH was higher than peak 1. Peak 1 of the PRL response was reached in 15min after TRH administration. Peak 1 of the PRL response was higher in the late follicular phase than in the early follicular and the luteal phase. This finding agreed with previous preports in women and monkey (Ferin et. al., 1974; Wang et. al., 1976; Yen et. al., 1976). Peak 1 of the PRL response to TRH was higher than peak 2 in all menstrual phases. Response ƒ 1 was greater than response ƒ 2. This response pattern was reversed in the gonadotropin response to LHRH. Because the first peak was higher than the second peak, it seems that the TRH had a strong releasing effect on PRL, but it had little priming effect on pituitary PRL. This finding supported Bremner's findings (1977). They used TRH constant continuous infusion for 4 hours in man. The PRL was rapidly increased to reach its peak level by min then decrease gradually in spite of the continuous TRH stimulations for a total of 240min. They concluded that the synthesis and release of the PRL may occur independentely. In our results, the PRL response was higher than the ƒ 2-60, and the longer the interval between the two consecutive TRH administrations the greater the increase was found to be. It seemed that the PRL response to TRH was time interval dependent or it might be due to the refractory of the PRL response to TRH. Arimura et al. (1973) reports on the effectiveness of the synthetic LHRH on LH release in rhesus monkey are conflicting. Ferin et. al. (1974) had administered doses of LHRH from 0.2 to 400ƒÊg and found that most monkys responded. In this experiment, we had administrated 100ƒÊg of LHRH and found most of the baboons were responsive. The length of time needed for the LH and FSH release after the LHRH in the baboon was similar to that in the rhesus monkey and human (Ferin et al., 1974; Yen et al., 1976; Rommler et al., 1979), The maximum level is reached within 60min after the administration of the LHRH. The LH response to the second bolus of LHRH was higher than the first response. The response to LHRH in the late follicular and luteal phase was stronger than in the early follicular phase. LH response ƒ 2-60 was higher than reversed in the luteal phase. In the luteal phase the was higher than the ƒ It may be due to the fact that some baboons still had responsed to LHRH after 60min. Indeed the LH was still elevated at 60min in some baboons in the follicular phase. We cannot therefore conclude that the longer time interval has favored the LH response or primed the LHRH effect. This discrepancy may be caused by the relative insensitivity of monkey to the LHRH as previously reported by Arimura et al. (1973). The FSH response to the second LHRH bolus was different from the LH response. The was higher than the in all menstrual phases. This was the opposite of the response during the follicular phase. It seems that the longer time interval is favorable for FSH response in this study.

7 Vol.32, No.4 LH, FSH AND PRL SECRETION ON FEMALE BABOONS 461 Acknowledgements We thank the National Institute of Arthritis, Metabolism and Digestive Disease and Dr. Niswender for FSH and LH Kits. The animal studies were coducted at the Experimental Animal Unit, School of Medicine, Kyoto University. This investigation was supported by the Ministry of Education, Science and Culture. We are grateful to Mr. K. Yamazaki, Mr. S. Yoshikawa and Mrs. K. Aso for assistance with animal care. References Aso, T., J.H. Su, M. Matsuoka, T. Motohashi and T. Nishimura (1979). The baboon as an animal model for research on human reproduction: The change in plasma prolactin levels under various conditions. Acta Obst. Gyne. Japan 31, Arimura, A., H. Spies, G. Schally and V. Andrew (1973). Relative insensitivity of rhesus monkeys LH-releasing hormone (LH-RH). J. Clin. Endocrinol. Metab. 36, Bremner, W.J., R. Abreu, J.R. Stockigt, D.M. de Kretser and H.G. Burger (1977). Pituitarythyroid responses to 4-hour constant infusions of thyrotropin releasing hormone in man. J. Clin. Endocrinol. Metab. 45, Bremner, W.J. and C.A. Paulsen (1974). Two pools of luteinizing hormone in the human pituitary: evidence from constant administration of luteinizing hormone-releasing hormone. J. Clin. Endocrinol.Metab. 39, Castro. A. and S.M. McCann (1975). Cyclic variations in the increased responsiveness of the pituitary to luteinizing hormone-releasing hormone (LHRH) induced by LHRH. Endocri. 97, Ferin, M., M. Warren, I. Dyrenfurth, V.R.L. Wiele, and W.F. White (1974). Response of rhesus monkeys to LRH throughout the ovarian cycle. J. Clin. Endocrinol. Metab. 38, Ferin, M., J. Bogumil, J. Drewes, I. Dyrenfurth, R. Jewelevicz and W.R.L. Vande (1978). Pituitary and ovarian hormonal response to 48h gonadotropin releasing hormone (GnRH) infusions in female rhesus monkeys. Acta Endocrinologica. 89, Hodgen, G.D., J. Wilks, J.L. Vaitukaitis, H.C. Chen, H. Papkoff and C.T. Ross (1976). A new radioimmunoassay for follicle-stimulating hormone in macaques: ovulatory menstrual cycles. Endocrinology 99, Hoff, J.D., B.L. Lasley and S.S.C. Yen (1979). The functional relationship between priming and releasing actions of luteinizing hormonereleasing hormone. J. Clin. Endocrinol. Metab. 49, Kastin, A.J., B.D. Gonzaley, H. Friesen, L.S. Jacobs, D.S. Schalch, A. Arimura, W.H. Daughaday and A.V. Schally (1973). Unaltered plasma prolactin levels in men after administration of synthetic LH-releasing hormone. J. Clin. Endocrinol. Metab. 36, Kletzky, O.A., V. Davajan and D.R. Mishell (1982). The effect of gonadotropin-releasing hormone on ovarian estradiol secretion. Am. J. Obstet. Gynecol. 142, McNeilly, A.S. and C. Hagen (1974). Prolactin, TSH, LH and FSH responses to a combined LHRH/TRH test at different stages of the menstrual cycle. Clinical Endocrinology 3, Niswender, G.D., S.E. Monroe, W.D. Peckham, A.R. Midgley, E. Knobil and L.E. Reichert (1971). Radioimmunoassay for rhesus monkey luteinizing hormone (LH) with antiovine LH serum and ovine LH-I. Endocrinologu 88, Pinto, H., B.L. Wajchenberg, F.B. Lima, J. Goldman, A.M. Comaru-Schally and A.V. Schally (1979). Evaluation of the gonadotrophic responsiveness of the pituitary to acute and prolonged administration of LH/FSH releasing hormone (LH-RH) in normal females and males. Acta Endocrinologica 91, Rebar, R., S.S.C. Yen, G. Vandenber, F. Naftolin, Y. Ehara, S. Engblom, K.J. Ryan, J. Rivier, M. Amoss and R. Guillemin (1973). Gonadotropin responses to synthetic LRF Doseresponse relationship in men. J. Clin. Endocrinol. Metab. 36, Rommler, A., S. Baumgarten, E. Schneller, U. Schwartz and J. Hammerstein (1978). Shortterm regulation of LH and FSH secretion in cyclic women. Acta Endocrinologica 88, Rommler, A., C. Viebahn, U. Schwartz and J. Hammerstein (1979). Short-term regulation of LH and FSH secretion in cyclic women. Acta

8 462 SU et al. Endocrinol. Japon. August, 1985 Endocrinologica 90, Su, J.H. (1981). The change in hypothalmicpituitary-ovarian function during peripubertal period in female baboons. Folia Endocrinol. Japan 57, Su, J.H., T. Aso, T. Motohashi, H. Aochi, M. Matsuoka, K. Horie and T. Nishimura (1980). Radioimmunoassay method for baboon plasma gonadotropins. Endocrinol. Japon 27, Takahashi, M., T. Makino, T. Yokokura, A. Nakayama, S. Takahashi, B.L. Lin, H. Suikane and R. Lizuka (1984). Diagnostic significance of LH-RH two step test in women with normoestrogenic Amenorrhea: Analysis of the selfpriming effect of the anterior pituitary glands. Acta Obst. Gunaec. Jpn. 36, No.5, Wang, C.F., B.L. Lasley, A. Lein and S.S.C. Yen (1976). The functional changes in the pituitary gonadotrophs during the menstrual cycle. J. Clin. Endocrinol. Metab. 42, Wentz, A.C. and R.N. Andersan (1980). Response to repetitive luteinizing hormonereleasing hormone stimuration in hypothalamic and pituitary disease. Am. J. Obstet. Gynecol. 138, Yen, S.S.C. and A. Lein (1976). The apparent paradox of the negative and positive feedback control system on gonadotropin secretion. Am. J. Obstet Gynecol. 126,