Effects of Priming Progesterone on the LH Surge Expressions in Ovariectomized Shiba Goats

다국어 초록 (Multilingual Abstract)

This study tested the hypothesis that the priming effects of progesterone on the timing of the LH surgeinduced by exogenous estradiol are more potentiated the negative feedback actions of progesterone on LH secretionby the existence of estradiol. In previous studies, the time interval from estradiol infusion until the peak of LH surgewas gradually and significantly extended by the different levels of progesterone treated before estradiol infusions. Longtermovariectomized Shiba goats that had received implants of estradiol capsules (Day 0) and three different progesteronesilastic packet inducing follicular, subluteal and luteal levels of progesterone were divided into three groups such asnon-P, low-P and high-P group. Blood samples were collected daily throughout the experiment for the analysis ofgonadal steroid hormone levels. On Day 7, all devices of progesterone and estradiol packets were removed but estradiolcapsules were maintained during the experiment, and blood samples were collected at 1 hr interval for 12 h from thetime of progesterone removals to determine peripheral changes of estradiol and progesterone concentration. Then allanimals were infused estradiol on the Day 7 after 13 h from the removals of progesterone devices with a peristalticpump into jugular vein at a rate of 3-6 μg/h for 36 h. For analysis of peripheral LH and estradiol concentration, bloodsamples were collected via another jugular vein at 2 h intervals for 52 h (from 4 h before the start of estradiol infusionto 48 h after the start of estradiol infusion). In all animals of the three groups treated with estradiol infusion, an LHsurge was expressed but the peak time of LH surge was different. This time interval was not extended by the differentlevels of progesterone treated before estradiol infusions and the difference was not significant during this intervalbetween the Low P and the High P groups. Progesterone pretreatment may contribute to regulating the neural systemthat is responded by estradiol, and estradiol existence potentiates the negative feedback effect of progesterone on GnRH/LH surge-generating system.

참고문헌 (Reference)

1 Dailey RA, "Use of prostaglandin F2 alpha or gonadotropin releasing hormone in treating problem breeding cows" 66 : 1721-1727, 1983

2 Orita J, "Ultrasonographic observation of follicular and luteal dynamics during the estrous cycle in Shiba goats" 46 : 31-37, 2000

3 Schams D, "The oestrous cycle of the cow: hormonal parameters and time relationships concerning oestrus, ovulation, and electrical resistance of the vaginal mucus" 86 : 180-192, 1977

4 Moenter S, "The estradiol-induced surge of gonadotropin-releasing hormone in the ewe" 127 : 1375-1384, 1990

5 Fabre-Nys C, "Roles of progesterone and estradiol in determining the temporal sequence and quantitative expression of sexual receptivity and the preovulatory LH surge in the ewe" 130 : 367-379, 1991

6 Taya K, "Radioimmunoassay for progesterone, testosterone and estradiol-17 beta using 125Iiodohistamine radioligands [in Japanese]" 31 : 186-196, 1985

7 Kasa-Vubu JA, "Progesterone blocks the estradiol-induced gonadotropin discharge in the ewe by inhibiting the surge of gonadotropin-releasing hormone" 131 : 208-212, 1992

8 Dobson H, "Plasma gonadotropins and oestradiol during oestrus in the cow" 52 : 51-53, 1978

9 Stock AE, "Ovarian follicular dominance in cattle: relationship between prolonged growth of the ovulatory follicle and endocrine parameters" 132 : 1108-1114, 1993

10 Kano Y, "Mammalian Reproductive Physiology: Aspects of its Animal Experimentation [in Japanese]" Soft Science 367-379, 1982

11 Tanaka T, "Long-term recording of hypothalamic GnRH pulse generator activity during programmed administration of progesterone and estradiol in the ovariectomized goat" 40 : 133-138, 1994

12 Sirois J, "Lengthening the bovine estrous cycle with low levels of exogenous progesterone: a model for studying ovarian follicular dominance" 127 : 916-925, 1990

13 Tanaka T, "Hypothalamic GnRH pulse generator activity during the estradiol-induced LH surge in ovariectomized goats" 56 : 641-645, 1992

14 Clarke IJ, "Gonadotrophin-releasing hormone secretion (GnRH) in anoestrous ewes and the induction of GnRH surges by oestrogen" 117 : 355-360, 1988

15 Tanaka T, "Fasting-induced suppression of pulsatile luteinizing hormone secretion is related to body energy status in ovariectomized goats" 72 : 185-196, 2002

16 Kesner JS, "Estradiol induces and progesterone inhibits the preovulatory surges of luteinizing hormone and follicle-stimulating hormone in heifers" 26 : 571-578, 1982

17 Nanda AS, "Effect of endogenous and exogenous progesterone on the oestradiol-induced LH surge in dairy cows" 84 : 367-371, 1988

18 Cavalieri J, "Effect of acute treatment with progesterone on the timing and synchrony of ovulation in Bos indicus heifers treated with a norgestomet implant for 17 days" 112 : 249-258, 1998

19 Skinner DC, "Duration and amplitude of luteal phase progesterone increment times the estradiolinduced luteinizing hormone surges in ewes" 63 : 1135-1142, 2000

20 Sanchez T, "Dosage of the synthetic progestin, norgestomet, influences luteinizing hormone pulse frequency and endogenous secretion of 17 beta-estradiol in heifers" 46 : 464-469, 1995

21 Kim S, "Different effects of subnormal levels of progesterone on the pulsatile and surge mode secretion of luteinizing hormone in ovariectomized goats" 69 : 141-145, 2003

22 Mori Y, "Changes in plasma concentrations of LH, progesterone and oestradiol in relation to the occurrence of luteolysis, oestrous and time of ovulation in the Shiba goat (Capra hircus)" 72 : 223-230, 1984

23 Caraty A, "Biphasic response in the secretion of gonadotropin-releasing hormone in ovariectomized ewes injected with oestradiol" 123 : 375-382, 1989