AUGMENTATION OF THE RAT UTERINE WEIGHT RESPONSE TO HUMAN CHORIONIC GONADOTROPHIN BY VARIOUS STEROIDS

1974 ◽  
Vol 75 (1) ◽  
pp. 141-147 ◽  
Author(s):  
L. J. Hipkin

ABSTRACT Dehydroepiandrosterone (DHA) augments the activity of human chorionic gonadotrophin (HCG) in the rat by increasing endogenous pituitary gonadotrophin secretion. The following experiments were undertaken to investigate the mechanism underlying this effect. Androstenedione (40 μg), dihydrotestosterone (200 μg) and testosterone (200 μg) augmented the rat uterine weight response to 0.5 IU of HCG. At these doses, the steroids did not affect basal uterine weight although this was increased when 1 mg of a steroid was injected. Androsterone (1 mg), 17α-hydroxypregnenolone (1 mg) and progesterone (200 μg) neither augmented HCG activity nor increased basal uterine weight. Ovarian weight differences were not significant in any of the experiments. Androstenedione, DHA, dihydrotestosterone and testosterone (200 μg dose level) did not significantly affect the uterine weight of castrated animals, and responses to 0.04 μg of oestradiol were not potentiated. The results with androstenedione, dihydrotestosterone and testosterone are identical to those obtained with DHA and suggest that these steroids may also increase pituitary gonadotrophin secretion.

1970 ◽  
Vol 64 (3) ◽  
pp. 421-430
Author(s):  
L. J. Hipkin

ABSTRACT A urinary extract (GIM), which previously had been shown to inhibit small doses of human chorionic gonadotrophin (HCG) in the mouse uterus assay, was tested in the rat. In this species, GIM caused an increase in the basal uterine weight and potentiated the response to 0.1 IU HCG. Similar results, and in addition augmentation of the activity of 0.2 IU HCG, were obtained in rats injected with carbon tetrachloride or starved. GIM inhibited the activity of 0.8 IU and 1.6 IU HCG. This was thought to result from the difference in mean final body weight between the GIM and the control groups. The results support the hypothesis that GIM causes a non-specific stress reaction. In rats the effect of this is to increase endogenous gonadotrophin secretion. This contrasts with the results previously reported for mice, which suggest that stress suppresses endogenous follicle-stimulating hormone release.


1955 ◽  
Vol 13 (1) ◽  
pp. 59-64 ◽  
Author(s):  
P. S. BROWN

SUMMARY Two convenient bioassays of urinary gonadotrophins, using immature mice, are described. The first is based upon the initial doubling of uterine weight. The second, using the ovarian weight response, attempts to increase specificity to follicle stimulating hormone by priming with human chorionic gonadotrophin. The usefulness of both methods is discussed, and the influence of non-specific impurities during the assay of urinary extracts is stressed.


1970 ◽  
Vol 64 (1) ◽  
pp. 95-102
Author(s):  
L. J. Hipkin

ABSTRACT The activity of human chorionic gonadotrophin (HCG) in the mouse uterus assay depends on the secretion of endogenous gonadotrophin. This source of gonadotrophin is suppressed when the animals are starved or injected with toxic substances, and the response to HCG is therefore inhibited. There is good evidence that this is the mode of action of the urinary gonadotrophin inhibitor (GIM). Since it has been claimed that stress-induced inhibition of gonadotrophin secretion is related to alterations in adrenocortical function, the present investigation is concerned with the response to HCG in animals with experimental hyper- and hypoadrenocorticalism. ACTH gel (300 mU) and a depot form of synthetic ACTH (15 μg) augmented the uterine weight response to HCG (0.5 IU). Normal responses were obtained in animals treated with HCG and either cortisol (300 μg), corticosterone (300 μg) or dehydroepiandrosterone (300 μg). Bilateral adrenalectomy produced similar effects to those previously described for GIM and stressful stimuli, namely, inhibition of HCG activity but no impairment of the responses to follicle-stimulating hormone (FSH), HCG given with FSH, or oestrone. It was thought that these results were produced by the metabolic and traumatic effects of the operation rather than by increased secretion of ACTH per se. Cortisol, corticosterone and ACTH gel did not influence the effect of GIM on HCG activity in the mouse uterus assay. The results suggest that suppression of endogenous gonadotrophin secretion following acute stress is not secondary to increased secretion of ACTH or hyperfunction of the adrenal cortex.


1970 ◽  
Vol 50 (1) ◽  
pp. 185-190 ◽  
Author(s):  
G. A. SHAW ◽  
B. E. McDONALD ◽  
R. D. BAKER

Reproductive tracts from 66 prepuberal, 45 cycling and 59 gonadotrophin-treated prepuberal gilts were examined and measured to determine the effect of puberty and gonadotrophin treatment on utero-ovarian interrelationships. Occurrence of the first ovulation resulted in significant (P < 0.05) increases in uterine weight and length but not in uterine wall thickness. This change was observed after both the first spontaneous ovulation and ovulation induced by injecting 1000 IU or 2000 IU of pregnant mare’s serum (PMS) followed 48 hours later by an injection of 500 IU of human chorionic gonadotrophin. Increasing the dose of PMS from 1000 IU to 2000 IU had no effect on uterine growth. Within untreated puberal females, ovarian weight was positively (P < 0.01) correlated with uterine horn weight, length and wall thickness, whereas within prepuberal females only uterine wall thickness was correlated (P < 0.01) with ovarian weight. Seven (41%) of the 17 gilts induced to ovulate at 55 kg and slaughtered at 90 kg were cycling when slaughtered, while none of the control females were cycling. Effects of the gonadotrophin treatment on tract development in prepuberal gilts were not apparent after the first spontaneous ovulation.


1965 ◽  
Vol 33 (3) ◽  
pp. 447-454
Author(s):  
M. J. K. HARPER

SUMMARY Administration of chlormadinone, an orally active progestational agent without significant oestrogenic activity, to intact immature female rats did not affect either ovarian or uterine weight significantly compared with controls. A single injection of human chorionic gonadotrophin (HCG) caused a 73 % increase in uterine weight in 24 hr. over the control value. This dose significantly increased ovarian weight and although it caused some stimulation of follicular development, ovulation during this time did not occur. When animals were treated with chlormadinone for 8 days, and received HCG on the 8th day, uterine weight was 170% greater than in the controls and 56% greater than with HCG alone. The uterine weight produced was similar to that found in animals treated with mestranol, a potent oestrogen, and HCG. In ovariectomized animals HCG did not affect uterine weight, while the small increase produced by chlormadinone was unaltered when HCG also was given. Mechanisms are discussed by which this augmentation of the uterine response to HCG might be produced. It seems most likely that chlormadinone administration causes storage of endogenous gonadotrophin in the pituitary, and that the exogenous gonadotrophin acts as the 'trigger' for the release of stored hormone, probably by a direct action on the hypothalamus.


1978 ◽  
Vol 89 (3) ◽  
pp. 492-505 ◽  
Author(s):  
D. M. Robertson ◽  
H. Suginami ◽  
H. Hernandez Montes ◽  
C. P. Puri ◽  
S. K. Choi ◽  
...  

ABSTRACT The presence of an hCG-like material in urinary and pituitary extracts and plasma obtained from non-pregnant subjects was investigated. Two assay methods were used to detect this material following fractionation of pituitary and urinary extracts by gel filtration (Ultrogel AcA 54) and/or isoelectrofocusing: a) a radioimmunoassay employing an antiserum raised against a specific sequence of the carboxy terminal region (residues 115– 145) of the β-subunit of hCG, and b) an in vitro bioassay method which measures both hLH and hCG activities. The fractionation procedures employed provide a satisfactory separation of highly purified hCG and hLH preparations. In the pituitary and urinary extracts hCGβ-peptide-like immunoactive (PIA) material was found consistently, which co-eluted with iodinated hCG following gel filtration and possessed pI values similar to those of hCG when subjected to isoelectrofocusing. The PIA material also exhibited in vitro biological activity similar to that shown by hLH and hCG. Detectable levels of immunoactive material were also found in plasma; however, the plasma levels of this PIA material were not influenced by classical endocrine measures such as the stimulation or inhibition of gonadotrophin secretion. The low levels of this material in plasma precluded its further characterization by gel filtration or electrofocusing. Whereas the present data and those reported by other investigators seem to suggest the presence of some hCG-like material in urinary and pituitary extracts and possibly in plasma of non-pregnant subjects, it is emphasized that the available evidence is not sufficiently conclusive to exclude other interpretations as to the nature of this material.


1999 ◽  
Vol 163 (2) ◽  
pp. 255-260 ◽  
Author(s):  
L Hinojosa ◽  
R Chavira ◽  
R Dominguez ◽  
P Rosas

The effects of thymulin administration beginning on days 19 or 24 of age on spontaneous puberty and gonadotrophin-induced ovulation were analysed in female normal and hypothymic mice. In normal and hypothymic mice, the daily administration of thymulin at 24 days of age resulted in a delay in the age of vaginal opening, with an increase in serum progesterone levels. Normal mice treated with 200 ng thymulin beginning on day 19 of age and injected with pregnant mare serum gonadotrophin (PMSG) 24 h later had an increase in ovulation rate, number of ova shed and weight of the ovaries. None of the hypothymic mice treated with thymulin on day 19 and PMSG on day 20 ovulated. PMSG treatment on day 25 induced ovulation in hypothymic mice. When these animals were injected previously with 200 ng thymulin, the number of ova shed by ovulating animals was lower than in PMSG-treated animals. Administration of thymulin and sequential injection of PMSG and human chorionic gonadotrophin 54 h later resulted in an increase in ovulatory response in comparison with those receiving only PMSG. The results suggest that thymulin plays a role in the regulation of spontaneous puberty through its effects on adrenal and ovarian endocrine functions. The increase in the ovarian PMSG response-treated animals, previously given thymulin, showed that this thymic hormone participates in the regulation of gonadotrophin secretion mechanisms and seems to be dose- and age-dependent. In hypothymic mice, neuroendocrine mechanisms regulating puberty are different from those of normal mice.


1966 ◽  
Vol 35 (2) ◽  
pp. 199-206 ◽  
Author(s):  
P. S. BROWN ◽  
M. WELLS

SUMMARY The follicle-stimulating hormone (FSH) content of urinary gonadotrophic extracts was assayed by its effect on the ovarian weight of immature mice when given in conjunction with 40 i.u. human chorionic gonadotrophin. About three-quarters of all routine assays gave values of λ between 0·15 and 0·30. Precision was slightly increased when the material was given in three rather than in five injections. Correction of ovarian weight for body weight was either invalid or of no value in reducing variance. Removal of between-litter variance increased precision considerably. Mice of three randomly bred colonies were all satisfactory, and inbred C57BL mice were also suitable for the assay. C3H mice were less sensitive. The efficiency of different methods of extracting FSH from urine was examined. The method of Johnsen (1958) using precipitation with tannic acid was considered the most satisfactory and gave extracts of high potency and low bulk. Limited experiments in which purified human pituitary FSH was assayed with and without added luteinizing hormone, gave results compatible with the assumption that the method is specific for FSH.


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