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

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

EFFECT OF GONADOTROPHINS ON THE SECRETION OF OESTRADIOL-17β AND TESTOSTERONE BY THE RAT TESTIS

1973 ◽  
Vol 57 (2) ◽  
pp. 277-284 ◽  
Author(s):  
F. H. DE JONG ◽  
A. H. HEY ◽  
H. J. van der MOLEN
Keyword(s):  
Intravenous Administration ◽  
Adult Male ◽  
Follicle Stimulating Hormone ◽  
Chorionic Gonadotrophin ◽  
Human Chorionic Gonadotrophin ◽  
Male Rats ◽  
Testosterone Concentration ◽  
Peripheral Plasma ◽  
Before And After ◽  
Venous Plasma

SUMMARY Concentrations of oestradiol-17β and testosterone were estimated in peripheral venous plasma and testicular venous plasma of adult male rats before and after administration of human chorionic gonadotrophin (HCG) or follicle-stimulating hormone (FSH). The concentration of oestradiol-17β in peripheral plasma, as measured with a radioimmunological technique, was 2·0 ± 0·9 (s.d.) pg/ml (n = 12). Peripheral testosterone concentrations were 2·4 ± 1·8 (s.d.) ng/ml (n = 21). Concentrations of oestradiol-17β and testosterone in testicular venous plasma were significantly higher than those in peripheral plasma. After intravenous administration of HCG (100 i.u.), oestradiol-17β and testosterone concentrations in testicular venous plasma increased significantly. After prolonged s.c. administration of HCG (5 days) the concentration of oestradiol-17β in testicular venous plasma did not change significantly, although the concentration of testosterone increased more than ten times. Intravenous administration of HCG after 5 days of pretreatment with HCG caused a significant increase in oestradiol-17β concentrations in testicular venous plasma. The increase in testosterone concentration was not significant under these conditions. Intravenous administration of FSH did not change oestradiol-17β or testosterone concentrations in testicular venous plasma.

STIMULATION BY HUMAN CHORIONIC GONADOTROPHIN OF OESTRADIOL PRODUCTION BY DISPERSED CELLS FROM HUMAN CORPUS LUTEUM: COMPARISON WITH PROGESTERONE PRODUCTION; UTILIZATION OF EXOGENOUS TESTOSTERONE

1981 ◽  
Vol 91 (2) ◽  
pp. 197-203 ◽  
Author(s):  
M. C. RICHARDSON ◽  
G. M. MASSON
Keyword(s):  
Luteal Phase ◽  
Chorionic Gonadotrophin ◽  
Human Chorionic Gonadotrophin ◽  
Cell Suspensions ◽  
Corpora Lutea ◽  
Progesterone Production ◽  
Late Luteal Phase ◽  
Oestradiol Production ◽  
Dispersed Cells

Cell suspensions were prepared from tissue samples of human corpora lutea obtained during the mid- and late-luteal phase of the menstrual cycle. Both oestradiol and progesterone production by dispersed cells were stimulated by similar concentrations of human chorionic gonadotrophin (hCG). As the degree of stimulation of production by hCG was greater for progesterone than for oestradiol (five- to tenfold compared with two- to threefold higher than basal production), the ratio of progesterone to oestradiol produced varied according to the level of trophic stimulation. A comparison of cell suspensions prepared from mid- and late-luteal phase corpora lutea, exposed to the same concentration of hCG (10 i.u./ml) in vitro, did not reveal a shift to oestradiol production in the late-luteal phase. Provision of additional testosterone during incubation raised the level of oestradiol production by dispersed luteal cells. At an optimum concentration of testosterone (1 μmol/l), oestradiol synthesis was not raised further in the presence of hCG or N6, O2-dibutyryl cyclic AMP, suggesting a lack of induction or activation of the aromatase system by gonadotrophin in short-term cultures. Basal and stimulated levels of progesterone production were not significantly impaired in the presence of testosterone.

SHORT-TERM EFFECTS OF COPULATION, HUMAN CHORIONIC GONADOTROPHIN INJECTION AND NON-TACTILE ASSOCIATION WITH A FEMALE ON TESTOSTERONE LEVELS IN THE MALE RAT

1974 ◽  
Vol 60 (3) ◽  
pp. 429-439 ◽  
Author(s):  
K. PURVIS ◽  
N. B. HAYNES
Keyword(s):  
Chorionic Gonadotrophin ◽  
Human Chorionic Gonadotrophin ◽  
Physical Contact ◽  
Male Rats ◽  
Male Rat ◽  
Plasma Testosterone ◽  
Short Term ◽  
Testosterone Levels ◽  
Peripheral Plasma ◽  
First Contact

SUMMARY Peripheral plasma testosterone levels in the male rat were increased above control levels 5 min after the first intromission with an oestrous female, or 8–10 min after first contact with the female. The levels remained raised for at least 30 min if copulation was allowed to continue. Intravenous injection of human chorionic gonadotrophin resulted in an increased peripheral concentration of plasma testosterone after 10–15 min and an increase of testosterone content of the testis 5–10 min after injection, indicating that the rat testis has a potential to respond rapidly to gonadotrophin. The results suggested that if the testosterone surge during copulation was gonadotrophin-dependent, it was initiated before the first intromission. Indeed, plasma testosterone levels were raised in male rats 5 min after being placed in the proximity of oestrous females but not allowed physical contact.

Oxytocin may play a role in the control of the human corpus luteum

1982 ◽  
Vol 95 (1) ◽  
pp. 65-70 ◽  
Author(s):  
G. J. S. Tan ◽  
R. Tweedale ◽  
J. S. G. Biggs
Keyword(s):  
Menstrual Cycle ◽  
Corpus Luteum ◽  
Inhibitory Action ◽  
Chorionic Gonadotrophin ◽  
Human Chorionic Gonadotrophin ◽  
Corpora Lutea ◽  
Luteal Cells ◽  
Progesterone Production ◽  
Human Corpus Luteum

The effects of oxytocin on dispersed luteal cells from human corpora lutea of the menstrual cycle were studied. Oxytocin at a concentration of 4 mi.u./ml produced a slight increase in basal progesterone production. However, higher oxytocin concentrations (400 and 800 mi.u./ml) markedly inhibited both basal and human chorionic gonadotrophin-induced progesterone production. These data provide evidence for an effect of oxytocin on the human corpus luteum. In view of the inhibitory action of oxytocin, increased secretion of this hormone may be important in the demise of the corpus luteum at the end of the menstrual cycle.

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.

CONCENTRATIONS OF CYCLIC AMP IN RABBIT OVARIAN TISSUE DURING THE PREOVULATORY PERIOD AND PSEUDOPREGNANCY AFTER INDUCTION OF OVULATION BY ADMINISTRATION OF HUMAN CHORIONIC GONADOTROPHIN

1975 ◽  
Vol 65 (1) ◽  
pp. 73-82 ◽  
Author(s):  
A. K. GOFF ◽  
PATRICIA W. MAJOR
Keyword(s):  
Cyclic Amp ◽  
Dose Response ◽  
Ovarian Tissue ◽  
Chorionic Gonadotrophin ◽  
Human Chorionic Gonadotrophin ◽  
Corpora Lutea ◽  
Response Relationship ◽  
Dose Response Relationship ◽  
Induction Of Ovulation ◽  
Relationship Of

SUMMARY Concentrations of cyclic AMP were measured in rabbit ovaries at various times after injection of an ovulatory dose of human chorionic gonadotrophin (HCG). A biphasic increase in cyclic AMP concentration occurred during the preovulatory period, with peaks 30 min and 3–4 h after HCG injection. Concentrations of cyclic AMP had returned to those observed in ovaries of control oestrous animals before the onset of ovulation 10–12 h after administration of HCG, and remained low throughout the period of pseudopregnancy. Concentrations of cyclic AMP in the newly formed and developing corpora lutea were similar to the concentrations observed in the remainder of the tissue during this period. No significant increase in cyclic AMP concentration was observed 7–9 days after initiation of ovulation. Concentrations of ATP were also investigated during the preovulatory period. The dose– response relationship of HCG to cyclic AMP production in oestrous rabbit ovaries was investigated.

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