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.

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

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.

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

MODIFICATIONS IN OVARIAN AND PITUITARY FUNCTION IN THE HYSTERECTOMIZED PREGNANT HAMSTER

1974 ◽  
Vol 61 (1) ◽  
pp. 45-51 ◽  
Author(s):  
G. S. GREENWALD
Keyword(s):  
Luteinizing Hormone ◽  
Sustained Release ◽  
Plasma Levels ◽  
Follicle Stimulating Hormone ◽  
Chorionic Gonadotrophin ◽  
Human Chorionic Gonadotrophin ◽  
Daily Injection ◽  
Rapid Decline ◽  
Antral Follicles ◽  
Pregnant Mare Serum Gonadotrophin

SUMMARY When hamsters were hysterectomized on day 1 of pregnancy, ovulation occurred 17 days later. On day 12 of this prolonged pseudopregnancy, plasma levels of progesterone were approximately half of those of intact animals on the same day of pregnancy. The concentration of follicle-stimulating hormone in the pituitary of the hysterectomized animals was only half that of the pregnant group, but luteinizing hormone concentrations were similar. The massive proliferation of antral follicles characteristic of pregnant hamsters on day 12 was not found in the hysterectomized animals; injection of 20 i.u. human chorionic gonadotrophin (HCG) on day 12 resulted in the ovulation of 31 and 6 ova respectively, but priming the hysterectomized hamsters with pregnant mare serum gonadotrophin (before HCG) resulted in superovulation. After hysterectomy on day 9 of pregnancy, by day 12 there was a rapid decline in luteal activity as shown histologically by the onset of structural luteolysis and a concomitant fall in luteal weight, and luteal and plasma levels of progesterone. These effects were partially or completely reversed by daily injection of 1 mg prolactin on days 9–11. The results indicate that hysterectomy before the establishment of the placenta results in the sustained release by the pituitary of prolactin and gonadotrophins, but most likely at lower levels than in pregnant animals. However, hysterectomy on day 9 abruptly removes the placental source of a prolactin-like hormone and the pituitary cannot respond in time to prevent luteolysis.

scholarly journals The effect of H-2 region and genetic background on hormone-induced ovulation rate, puberty, and follicular number in mice

1991 ◽  
Vol 57 (1) ◽  
pp. 41-49 ◽  
Author(s):  
J. L. Spearow ◽  
R. P. Erickson ◽  
T. Edwards ◽  
L. Herbon
Keyword(s):  
Genetic Background ◽  
Follicular Development ◽  
Chorionic Gonadotrophin ◽  
Human Chorionic Gonadotrophin ◽  
Ovulation Rate ◽  
Follicular Atresia ◽  
Linked Gene ◽  
Induced Ovulation ◽  
Follicular Maturation ◽  
Timing Of Puberty

SummaryWe have examined the effects of major histocompatibility (H-2) haplotypes and genetic background (all loci other than the H-2 region) on hormone-induced ovulation rate in congenic strains of mice. In comparison with the H-2a haplotype, the H-2b haplotype increased hormone-induced ovulation rate 92% on the A/J (A) genetic background. However, H-2 haplotype did not affect hormone-induced ovulation rate on the C57BL/10J (C57) genetic background. The H-2b-linked gene(s) increased hormone-induced ovulation rate on the A/J genetic background largely by (1) enhancing the maturation of follicles in response to pregnant mare's serum gonadotrophin (PMSG) and (2) altering the stages of follicular development which can be induced to ovulate in response to human chorionic gonadotrophin (hCG). The observed effects of H-2 on hormone-induced ovulation rate were not explained by differences in the timing of puberty, the number of follicles present in untreated females, or the incidence of follicular atresia. The effect of genetic background on hormone-induced ovulation rate was much greater than was the effect of the H-2 region. We found that hormone-induced ovulation rate was five- to six-fold higher on the C57 genetic background than on the A genetic background. The C57 genetic background increased hormone-induced ovulation rate by (1) enhancing the induction of follicular maturation in response to gonadotropins and (2) by reducing the incidence of follicular atresia.

FOLLICULAR DEVELOPMENT IN THE ADULT GUINEA-PIG AND RESPONSES TO HUMAN CHORIONIC GONADOTROPHIN

1980 ◽  
Vol 85 (1) ◽  
pp. 9-16 ◽  
Author(s):  
M. J. PEDDIE
Keyword(s):  
Luteal Phase ◽  
Continuous Process ◽  
Follicular Development ◽  
Chorionic Gonadotrophin ◽  
Human Chorionic Gonadotrophin ◽  
Follicular Growth ◽  
Antral Follicles ◽  
Late Luteal Phase ◽  
Cycle Lengths ◽  
Two Stages

SUMMARY The development of antral follicles and of atretic follicles throughout the cycle of adult guinea-pigs is a continuous process, but there are two stages when atresia is most pronounced: immediately after oestrus and in the late luteal phase. New atretic antral follicles were not found in the ovaries until around day 10 of the cycle, when an injection of HCG caused atresia of the medium-sized antral follicles within the ovary and luteinization of the largest follicles but spared the smallest antral follicles. Following the induced atresia, cycle lengths were prolonged, but the population of antral follicles could be restored to normal within 10 days of gonadotrophin treatment. It is suggested that the growth rate of antral follicles is flexible and proceeds most rapidly at the end of the luteal phase. It is not clear whether ovarian steroids play an integral part in regulating follicular growth and atresia.

THE EFFECT OF A SINGLE INJECTION OF DIETHYLSTILBOESTROL OR PROGESTERONE ON THE HAMSTER OVARY

1965 ◽  
Vol 33 (1) ◽  
pp. 13-23 ◽  
Author(s):  
G. S. GREENWALD
Keyword(s):  
Anterior Pituitary ◽  
Single Injection ◽  
Follicular Development ◽  
Chorionic Gonadotrophin ◽  
Human Chorionic Gonadotrophin ◽  
Oestrous Cycle ◽  
The Other ◽  
Follicular Atresia ◽  
Follicular Growth ◽  
Antral Follicles

SUMMARY A single injection of 0·25 mg. stilboestrol or 5 mg. progesterone at metoestrus (day 1) affected follicular development in the hamster ovary in different ways. Stilboestrol induced widespread follicular atresia but apparently did not interfere with the release of ovulating hormone at the end of the oestrous cycle. The atresia produced by stilboestrol appears to be mediated by changes in the levels of circulating gonadotrophin rather than by a direct effect on the ovary. This was demonstrated by injecting pregnant mare serum on day 1 of the cycle followed by stilboestrol treatment at various times thereafter. Under these circumstances the ovulation rate was only reduced below control values when stilboestrol was injected on day 1. Progesterone given on day 1 of the cycle did not interfere with the maturation of healthy Graafian follicles but acted on the terminal stages of follicular growth by blocking ovulation. After a single injection of progesterone, the life span of antral follicles was prolonged to 8–9 days. The ovulation-inhibiting effects of progesterone given on day 1 of the cycle were overcome by the injection of human chorionic gonadotrophin on day 4. Thus, progesterone blocked ovulation indirectly by preventing release of ovulating hormone from the anterior pituitary. The effects of shifting the single injection of stilboestrol or progesterone to the other days of the oestrous cycle are also considered.

Luteinizing hormone increases the number of ova shed in the cyclic hamster and guinea-pig

1984 ◽  
Vol 101 (3) ◽  
pp. 289-298 ◽  
Author(s):  
F. Garza ◽  
M. A. Shaban ◽  
P. F. Terranova
Keyword(s):  
Guinea Pig ◽  
Binding Sites ◽  
Follicular Development ◽  
Chorionic Gonadotrophin ◽  
Human Chorionic Gonadotrophin ◽  
Serum Concentrations ◽  
Sustained Development ◽  
Antral Follicles ◽  
Preovulatory Follicles ◽  
Pregnant Mare Serum Gonadotrophin

ABSTRACT Osmotic minipumps containing 400 μg ovine LH installed subcutaneously on day 1 (oestrus) of the cycle in the hamster induced superovulation of 30·0 ± 2·1 ova (n=5) at the next expected oestrus. Controls ovulated 12·0 ± 0·8 ova (n = 6). Bovine LH, human LH, porcine LH, human chorionic gonadotrophin and pregnant mare serum gonadotrophin were effective in approximately doubling the number of ova spontaneously shed in the hamster. Ovine FSH (200 μg/pump) was most effective in increasing the number of ova spontaneously shed (55 ± 6, n=5) in the hamster. Infusion of ovine LH on days 1–4 prevented the reduction of the number of antral follicles that occurs normally between days 3 and 4 of the 4-day cycle. Since this reduction in follicular numbers in control cyclic hamsters is due to atresia, the exogenous LH might prevent atresia of the developing follicles. In the hamster, exogenous ovine LH significantly increased the serum concentrations of androstenedione, oestradiol and LH but not of FSH. Hamsters were hypophysectomized on the day of oestrus, given immediate LH (400 pg) or FSH (200 μg) replacement therapy and autopsied on day 4. Ovarian histology revealed that immediate LH treatment after hypophysectomy sustained development of histologically normal preovulatory follicles but had no effect on the number of smaller sizes of follicles. Immediate FSH treatment after hypophysectomy increased only the number of smaller sized follicles. Since LH did not increase the smaller sized follicles, no 'FSH-like' effect on follicular development was observed. In the hamster, the ability of various preparations of LH to induce superovulation did not correlate with their ability to displace 125I-labelled ovine FSH from its ovarian binding sites. The superovulatory action of LH required the presence of the pituitary gland, indicating that LH might synergize with FSH and/or prolactin (or hamster LH) for spontaneous superovulation and it appears that exogenous LH might induce superovulation by prevention of atresia. Infusion of LH into the guinea-pig beginning on day 12 of the cycle (day 1 is the day of ovulation) doubled the ovulation rate whereas in the cyclic rat and mouse LH treatment throughout the cycle was ineffective in increasing the number of ova shed. J. Endocr. (1984) 101, 289–298

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

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

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