Induced development of ovulatory follicles during the early stages of lactation by the administration of LH in the rat

1988 ◽  
Vol 116 (1) ◽  
pp. 115-122 ◽  
Author(s):  
K. Taya ◽  
S. Sasamoto
Keyword(s):  
Important Determinant ◽  
Plasma Concentrations ◽  
Chorionic Gonadotrophin ◽  
Human Chorionic Gonadotrophin ◽  
The Other ◽  
Follicular Maturation ◽  
Early Stages ◽  
Ovulatory Follicles ◽  
And Control ◽  
Venous Plasma

ABSTRACT To determine whether failure of follicular maturation during the early stages of lactation in rats is due to inadequate LH stimulation, lactating rats nursing eight pups were injected twice daily for 1–3 days (days 2–5 of lactation) with various doses of ovine LH. Follicular maturation was determined by the ability of the follicles to ovulate in response to 10 IU human chorionic gonadotrophin (hCG), endogenous oestradiol-17β and inhibin production. Ovulation was not induced in control animals in response to 10 IU hCG given between days 2 and 5 of lactation. On the other hand, an injection of 10 IU hCG could induce ovulation in LH-treated animals, in which 25 and 50 μg LH per injection were given s.c. from days 2 to 5 of lactation. Concentrations of oestradiol-17β and inhibin activity in ovarian venous plasma increased progressively after the administration of LH, indicating that induced development of ovulatory follicles had occurred. Plasma concentrations of FSH declined in LH-treated animals compared with those in control animals. The decrease in plasma concentrations of FSH was not observed when lactating rats were ovariectomized before the first injection of LH, indicating that ovarian products, probably inhibin, from developing follicles may suppress the secretion of FSH from the pituitary gland. In both LH-treated and control animals, concentrations of prolactin and progesterone remained increased during the period of LH administration. The present results, therefore, suggest that the plasma levels of LH are an important determinant of follicular maturation during lactation in rats. J. Endocr. (1988) 116, 115–122

Selective release of FSH in lactating rats during the period of follicular atresia induced by the administration of antiserum to LH-releasing hormone

1988 ◽  
Vol 118 (3) ◽  
pp. 455-464 ◽  
Author(s):  
K. Taya ◽  
S. Sasamoto
Keyword(s):  
Gradual Increase ◽  
Plasma Concentrations ◽  
Inhibitory Effect ◽  
Negative Influence ◽  
Chorionic Gonadotrophin ◽  
Human Chorionic Gonadotrophin ◽  
Follicular Atresia ◽  
Follicular Maturation ◽  
Lh Releasing Hormone ◽  
Venous Plasma

ABSTRACT Passive immunoneutralization of LHRH by injecting a caprine antiserum to LHRH (LHRH-AS) in lactating rats nursing two pups on day 5 of lactation resulted in an immediate decline in concentrations of LH in the plasma during the 24-h study period, followed by a gradual increase to control levels 30 h later. Concentrations of oestradiol-17β and inhibin activity in ovarian venous plasma also decreased abruptly in LHRH-AS treated animals and recovered to control levels 36 h later. These changes were correlated with changes in concentrations of LH in the plasma. On the other hand, plasma concentrations of FSH increased abruptly in the LHRH-AS treated animals within 3 h after injection, but the concentrations declined gradually to control levels 48 h later. The ability of follicles to ovulate in response to human chorionic gonadotrophin (hCG) began to decrease within 6 h after treatment with LHRH-AS, and further decreased until 18 h after injection of LHRH-AS, when hCG induced ovulation (with two oocytes) in only one of five animals. A gradual increase in ovulation rate to control levels was noted by 36 h after injection of LHRH-AS. These results indicate that Graafian follicles present at the time of LHRH-AS injection had become atretic and that a new set of follicles had then begun to mature. Selective release of FSH could not be induced by injection of LHRH-AS in ovariectomized animals. Treatment with inhibin (porcine follicular fluid) suppressed the selective release of FSH, whereas treatment with oestradiol-17β had no inhibitory effect on the selective release of FSH. These findings indicate (1) that tonic secretion of LH is an important factor in normal follicular maturation and maintenance in lactating rats, (2) that selective release of FSH after injection of LHRH-AS is attributed to the removal of a negative influence of inhibin from antral follicles during the period of follicular atresia and (3) that a selective surge of FSH is responsible for initiation of new follicular maturation. J. Endocr. (1988) 118, 455–464

Follicular dynamics and secretion of inhibin and oestradiol-17β during the oestrous cycle of the hamster

1995 ◽  
Vol 146 (1) ◽  
pp. 169-176 ◽  
Author(s):  
H Kishi ◽  
K Taya ◽  
G Watanabe ◽  
S Sasamoto
Keyword(s):  
Plasma Levels ◽  
Marked Decrease ◽  
Plasma Concentrations ◽  
Follicular Development ◽  
Chorionic Gonadotrophin ◽  
Human Chorionic Gonadotrophin ◽  
Oestrous Cycle ◽  
Antral Follicles ◽  
Follicular Maturation ◽  
Follicular Dynamics

Abstract Plasma and ovarian levels of inhibin were determined by a radioimmunoassay (RIA) at 3-h intervals throughout the 4-day oestrous cycle of hamsters. Plasma concentrations of FSH, LH, progesterone, testosterone and oestradiol-17β were also determined by RIAs. In addition, hamsters were injected at various times with human chorionic gonadotrophin (hCG) to determine the follicular development. The changes in plasma concentrations of FSH after injection of antisera to oestradiol-17β (oestradiol-AS) and inhibin (inhibin-AS) on the morning of day 2 (day 1=day of ovulation) were also determined. Plasma concentrations of inhibin showed a marked increase on the afternoon of day 1, remained at plateau levels until the morning of day 4, then increased abruptly on the afternoon of day 4 when preovulatory LH and FSH surges were initiated. A marked decrease in plasma concentrations of inhibin occurred during the process of ovulation after the preovulatory gonadotrophin surges. An inverse relationship between plasma levels of FSH and inhibin was observed when the secondary surge of FSH was in progress during the periovulatory period. Plasma concentrations of oestradiol-17β showed three increase phases and these changes differed from those of inhibin. Changes in plasma concentrations of oestradiol-17β correlated well with the maturation and regression of large antral follicles. Follicles capable of ovulating following hCG administration were first noted at 2300 h on day 1. The number of follicles capable of ovulating reached a maximum on the morning of day 3 (24·8± 0·6), and decreased by 0500 h on day 4 (15·0 ± 1·1), corresponding to the number of normal spontaneous ovulations. Plasma concentrations of FSH were dramatically increased within 6 h after inhibin-AS, though no increase in FSH levels was observed after oestradiol-AS. These findings suggest that changes in the plasma levels of inhibin during the oestrous cycle provide a precise indicator of follicular recruitment, and that the changes in plasma concentrations of oestradiol-17β are associated with follicular maturation. These findings also suggest that inhibin may play a major role in the inhibition of FSH secretion during the oestrous cycle of the hamster. Journal of Endocrinology (1995) 146, 169–176

INITIATION OF FOLLICULAR MATURATION AND OVULATION AFTER REMOVAL OF THE LITTER FROM THE LACTATING RAT

1980 ◽  
Vol 87 (3) ◽  
pp. 393-400 ◽  
Author(s):  
KAZUYOSHI TAYA ◽  
SHUJI SASAMOTO
Keyword(s):  
Plasma Levels ◽  
Plasma Concentrations ◽  
Follicular Development ◽  
Chorionic Gonadotrophin ◽  
Human Chorionic Gonadotrophin ◽  
Moderate Increase ◽  
Normal Cycle ◽  
Antral Follicles ◽  
Follicular Maturation ◽  
Follicular Activity

In order to elucidate the mechanism of the resumption of follicular activity and ovulation in rats, levels of FSH, LH and prolactin in plasma and pituitary gland and ovarian follicular development were quantified after removal of the litter on day 3 of lactation (day of parturition = day 0 of lactation). Such removal resulted in ovulation of 13 oocytes 4 days later, a number comparable with that found in normal cyclic rats. Plasma levels of prolactin were high during lactation but markedly decreased after removal of the litter. Although plasma concentrations of FSH and LH did not change during days 3–7 of lactation, there was an FSH surge between 24 and 30 h after removal of the litter. Plasma concentrations of LH also increased slightly but significantly by 24 h after removal of the litter and this value persisted during the following 2 days. Surges of FSH, LH and prolactin occurred at 17.00 h 3 days after pups were removed. Removal of the litter did not increase pituitary contents of FSH, LH and prolactin and a marked reduction in pituitary levels of FSH and LH, but not of prolactin, occurred at 17 00 h 3 days after removal of the litter. A quantitative study of follicular development indicated that follicles larger than 401 μm in diameter were absent during days 3–7 of lactation. However, the number and size of antral follicles increased by 30 h after removal of the litter, probably due to the increases in plasma levels of FSH and LH, and follicles larger than 601 μm in diameter appeared 3 days after the young were removed. Although ovulation could not be induced by human chorionic gonadotrophin from days 3 to 5 of lactation, its administration 30 h after removal of the litter produced ovulation in all rats by the following morning. These results indicated that a moderate increase in FSH, although below the amounts released at the preovulatory surge, together with basal levels of LH which were within the range observed on the day of dioestrus during the normal cycle were responsible for the initiation of follicular maturation after removal of the litter.

Prolactin effects on basal and gonadotrophin-stimulated progesterone accumulation by PMSG-primed mouse ovaries in vitro

1985 ◽  
Vol 110 (4) ◽  
pp. 553-557 ◽  
Author(s):  
Julie A. Jonassen ◽  
Alan S. McNeilly
Keyword(s):  
Incubation Period ◽  
Chorionic Gonadotrophin ◽  
Human Chorionic Gonadotrophin ◽  
Immature Female ◽  
Female Mice ◽  
Follicular Maturation ◽  
Progesterone Secretion ◽  
Ovulatory Follicles ◽  
Primed Mouse

Abstract. To examine the effects of prolactin (Prl) and human chorionic gonadotrophin (hCG) on progesterone production by murine ovarian explants, immature female mice were injected with 4 IU pregnant mare's serum gonadotrophin (PMSG) to induce follicular maturation. After 24 or 40 h mice were killed, ovaries removed, cut into fragments and maintained as explants for 24 h in the presence or absence of ovine or human Prl (25–2500 ng/ml). None of these doses of Prl affected basal progesterone accumulation into media over 24 h. To determine if Prl could modify the capacity of ovarian explants to respond to gonadotrophin, ovaries were incubated with 25 IU/ml hCG for 3 h after an initial 24 h incubation period with or without Prl. Prl had no effect on basal progesterone accumulation but significantly enhanced hCG-stimulated progesterone accumulation during the 3 h incubation period. We conclude that Prl does not inhibit but may enhance progesterone secretion by pre-ovulatory follicles in the mouse.

Adrenal and gonadal function in hypothyroid adult male rats

1997 ◽  
Vol 152 (1) ◽  
pp. 147-154 ◽  
Author(s):  
A Tohei ◽  
M Akai ◽  
T Tomabechi ◽  
M Mamada ◽  
K Taya
Keyword(s):  
Adult Male ◽  
Functional Relationship ◽  
Plasma Concentrations ◽  
Gonadal Hormones ◽  
Chorionic Gonadotrophin ◽  
Human Chorionic Gonadotrophin ◽  
Male Rats ◽  
Plasma Acth ◽  
Corticosterone Release ◽  
Acth Release

Abstract The functional relationship between thyroid, adrenal and gonadal hormones was investigated using adult male rats. Hypothyroidism was produced by the administration of 4-methyl-2-thiouracil (thiouracil) in the drinking water for 2 weeks. Plasma concentrations of TSH dramatically increased, whereas plasma concentrations of tri-iodothyronine and thyroxine decreased in thiouracil-treated rats as compared with euthyroid rats. Hypothyroidism increased basal levels of plasma ACTH and pituitary content of ACTH. The pituitary responsiveness to CRH for ACTH release markedly increased, whereas the adrenal responsiveness to ACTH for corticosterone release decreased. These results indicated that hypothyroidism causes adrenal dysfunction in adult male rats. Pituitary contents of LH and prolactin decreased in hypothyroid rats as compared with euthyroid rats. In addition, hypothyroidism lowered pituitary LH responsiveness to LHRH. Testicular responsiveness to human chorionic gonadotrophin for testosterone release, however, was not different between euthyroid and hypothyroid animals. These results indicated that hypothyroidism causes adrenal dysfunction and results in hypersecretion of ACTH from the pituitary gland. Adrenal dysfunction may contribute to the inhibition of LHRH secretion from the hypothalamus, possibly mediated by excess CRH. Journal of Endocrinology (1997) 152, 147–154

THE EFFECT OF INTRAVENOUSLY ADMINISTERED HUMAN CHORIONIC GONADOTROPHIN ON PLASMA LEVELS OF TESTOSTERONE AND 5α-DIHYDROTESTOSTERONE IN NORMAL MALE SUBJECTS

1973 ◽  
Vol 72 (3) ◽  
pp. 615-624 ◽  
Author(s):  
W. Maurer ◽  
U. Volkwein ◽  
J. Tamm
Keyword(s):  
Plasma Levels ◽  
Initial Phase ◽  
Plasma Concentrations ◽  
Chorionic Gonadotrophin ◽  
Human Chorionic Gonadotrophin ◽  
Plasma Testosterone ◽  
Normal Male ◽  
Peripheral Conversion ◽  
Male Subjects

ABSTRACT HCG was infused intravenously into normal male subjects. The doses administered were 500, 100 and 50 IU, respectively. During the initial phase of the infusions the plasma testosterone (T) levels decreased. Thirty minutes after starting the infusion of 500 and 100 IU HCG, respectively, the plasma testosterone increased. Significantly elevated values were observed 60 to 180 minutes after the cessation of HCG administration. The dihydrotestosterone (DHT) concentrations in the plasma showed a varying pattern. On the average this steroid also exhibited an increase in plasma following the HCG administration. From the results no conclusions can be drawn as to the extent to which the plasma concentrations of DHT have been influenced by a secretion from the testes or by a peripheral conversion of T into DHT.

Human chorionic gonadotrophin raises serum immunoreactive inhibin levels in men with hypogonadotrophic hypogonadism

1990 ◽  
Vol 2 (2) ◽  
pp. 137 ◽  
Author(s):  
HG Burger ◽  
SC Tiu ◽  
ML Bangah ◽  
Kretser DM de
Keyword(s):  
Chorionic Gonadotrophin ◽  
Human Chorionic Gonadotrophin ◽  
The Other ◽  
Glycoprotein Hormone ◽  
Hypogonadotrophic Hypogonadism

Inhibin is a gonadal glycoprotein hormone involved in the regulation of FSH. To elucidate the regulation of inhibin production we investigated the acute (daily for 1 week) and chronic (9-10 months of follow-up) changes in immunoreactive inhibin, testosterone, LH and FSH levels in the serum of three hypogonadotrophic hypogonadal patients treated first with hCG alone (for 3-6 months) and then hCG combined with FSH (1-5 months). One patient was unexpectedly resistant to gonadotrophin therapy; in the other two, hCG, with or without FSH, caused a rise in inhibin and testosterone, supporting previous observations that LH, as well as FSH, plays a role in the regulation of inhibin or inhibin-related peptides in men.

THE SECRETION OF DEHYDROEPIANDROSTERONE AND DEHYDROEPIANDROSTERONE SULPHATE IN MAN

1973 ◽  
Vol 57 (1) ◽  
pp. 123-134 ◽  
Author(s):  
E. NIESCHLAG ◽  
D. L. LORIAUX ◽  
H. J. RUDER ◽  
I. R. ZUCKER ◽  
M. A. KIRSCHNER ◽  
...  
Keyword(s):  
Diurnal Variation ◽  
Adrenal Cortex ◽  
Biosynthetic Pathway ◽  
Chorionic Gonadotrophin ◽  
Human Chorionic Gonadotrophin ◽  
Dehydroepiandrosterone Sulphate ◽  
Venous Plasma

SUMMARY The secretion of dehydroepiandrosterone (DHA) and its sulphate (DHAS) was examined by measuring their concentrations in adrenal venous, gonadal venous, and peripheral venous plasma. Both steroids were secreted by the adrenal cortex and the rate of DHA secretion was higher than that of DHAS in seven out of eight subjects. Adrenocorticotrophin (ACTH) caused an increase in DHA and DHAS secretion by 15–30 min after administration. When ACTH was infused for 8 h, peripheral DHA concentrations increased at 2 h and decreased subsequently in five out of eight subjects suggesting depletion of substrate or cofactors for this biosynthetic pathway. Gonadal secretion of DHA was present in each subject (eight women and two men) but DHAS secretion could not be demonstrated. Exogenous human chorionic gonadotrophin (HCG) caused an increase in plasma DHA. Examination of the diurnal variation of plasma DHA concentrations revealed a 40% decrease from 08.00 to 20.00 h.

Induction of selective release of FSH in castrated male rats bearing an ovarian transplant by the administration of human chorionic gonadotrophin

1985 ◽  
Vol 106 (1) ◽  
pp. 31-NP ◽  
Author(s):  
G. Watanabe ◽  
K. Taya ◽  
S. Sasamoto
Keyword(s):  
Adult Male ◽  
Sex Differentiation ◽  
Plasma Concentrations ◽  
Chorionic Gonadotrophin ◽  
Human Chorionic Gonadotrophin ◽  
Male Rats ◽  
Corpora Lutea ◽  
Female Rat ◽  
Nacl Solution ◽  
Abrupt Decrease

ABSTRACT The present study was undertaken to determine whether hypothalamic differentiation is involved in the selective release of FSH during the periovulatory period using adult male rats castrated and implanted with an ovary. Adult male rats (70–90 days old) were castrated and an ovary obtained from a prepubertal female rat (26 days old) was immediately grafted subcutaneously. Four weeks later, human chorionic gonadotrophin (hCG, 10 i.u.) was injected i.v. into the experimentally manipulated rats to induce ovulatory changes in the grafted ovaries. Another group of similarly prepared rats was injected with 0·9% (w/v) NaCl solution as controls. After injection of hCG, plasma concentrations of FSH increased significantly by 6 h, reached peak values at 12 h and declined to control levels at 36 h. On the other hand, plasma concentrations of LH were reduced by 6 h and decreased further during the next 36 h. An abrupt fall in plasma concentrations of oestradiol-17β occurred within 3 h of the administration of hCG. Histological examination revealed that ovulatory changes and luteinization of follicles were induced in grafted ovaries by 18 h after the injection of hCG. Thirty-six hours after treatment with hCG, a set of newly formed corpora lutea was observed in grafted ovaries and plasma concentrations of progesterone were raised. Treatment with oestradiol-17β did not inhibit the selective release of FSH after the administration of hCG, suggesting that the abrupt decrease in secretion of oestradiol-17β from the grafted ovary is not involved in the occurrence of the FSH surge. These results indicate that a selective release of FSH can be induced in castrated male rats bearing an ovarian transplant probably due to decreased secretion of inhibin by the luteinized follicles in the grafted ovaries. Sex differentiation of the hypothalamus is not, therefore, involved in the selective surge of FSH. J. Endocr. (1985) 106, 31–36

EFFECTS OF HUMAN CHORIONIC GONADOTROPHIN ON THE RELEASE OF CYCLIC AMP AND PROGESTERONE FROM THE SHEEP OVARY AT DIFFERENT STAGES OF THE OESTROUS CYCLE

1978 ◽  
Vol 89 (1) ◽  
pp. 158-165 ◽  
Author(s):  
T. J. Weiss ◽  
P. O. Janson ◽  
K. J. Porter ◽  
R. F. Seamark
Keyword(s):  
Cyclic Amp ◽  
Corpus Luteum ◽  
Chorionic Gonadotrophin ◽  
Human Chorionic Gonadotrophin ◽  
Oestrous Cycle ◽  
Secretion Rate ◽  
Arterial Plasma ◽  
Venous Plasma

ABSTRACT The rate of release of cyclic AMP by sheep ovaries containing a corpus luteum was determined at different stages of the cycle before and up to 60 min after an intra-arterial (ia) injection of 500 IU human chorionic gonadotrophin (hCG). The median cyclic AMP concentration in arterial plasma and of ovarian venous plasma following hCG stimulation was 93.2 and 98.0 pmol/ml, respectively. The ovaries of ewes examined at Days 1 and 2 of the cycle showed no response to hCG, whereas in 2 sheep at Day 3, hCG caused a slight response, and in 13 sheep examined between Days 5–18, hCG caused a marked increase in cAMP release. In 5 of the sheep in which both ovarian veins were cannulated, only the ovary with a corpus luteum responded to hCG with an increased secretion rate of cyclic AMP and progesterone. The results indicate a lack of responsiveness in the newly formed corpus luteum to hCG.

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