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Search for other papers by D. L. INGRAM in
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Search for other papers by ANITA M. MANDL in
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SUMMARY
Adult rats which had been previously sterilized by means of X-rays were hypophysectomized a fortnight after the onset of continuous vaginal cornification (which begins within 40 days of X-irradiation [Mandl & Zuckerman, 1956]). The animals, including non-irradiated hypophysectomized controls, were killed at periods of 5–70 days after hypophysectomy.
Cornified cells disappeared from the vaginal smear of non-irradiated rats within 3, and of irradiated rats within 4 days after hypophysectomy. The ovaries involuted rapidly in both groups of animals. Stromal cells decreased in size and post-hypophysectomy 'deficiency cells' appeared. On the other hand, the rate of uterine involution was slower in the X-irradiated animals after hypophysectomy than in the non-irradiated hypophysectomized controls. This finding indicates that in the absence of the pituitary, the X-irradiated ovary can produce more oestrogen than a non-irradiated ovary, or that the oestrogen it produces is biologically more active.
After treatment with gonadotrophin, the 'deficiency cells' in the ovaries of both groups of animals disappeared. The X-irradiated hypophysectomized animals responded to the gonadotrophin less vigorously (as judged by an increase in ovarian and uterine size) than did the hypophysectomized controls.
Search for other papers by M. BEN-DAVID in
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SUMMARY
Mammary-gland development and milk secretion were induced in virgin adult female Fischer rats by treatment with perphenazine (Trilafon) for 5 days. The drug, however, failed to induce similar lactation in ovariectomized adult animals or in juvenile rats unless the animals were pretreated with small quantities of oestradiol, indicating that when the ovaries are absent, or almost inactive as in juvenile rats, oestradiol-priming is a prerequisite for perphenazine-induced lactation.
When perphenazine was given to adult rats starting at early dioestrus, the following changes occurred: (1) a continuous dioestrus ensued lasting about 7 days after the end of treatment; (2) the ovaries were predominantly occupied by corpora lutea, and (3) a typical pseudopregnant 'lucid zone' appeared in the uterine endometrium.
It is concluded that perphenazine treatment most likely stimulated secretion of luteotrophic hormone, which in rats seems to be identical with prolactin in its promotion of lactogenesis.
Search for other papers by W. S. BULLOUGH in
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The action of oestrogens on the development and periodic changes of the female accessory sexual organs of the mammals is well known, but it now appears probable that this secretion also influences the growth of the various parts of the ovary itself. A striking coincidence has recently been demonstrated between the positions of high concentrations of oestrogen in the mouse ovary and local areas of mitotic activity in the germinal epithelium, and it is not unlikely that the three nuclear divisions of oogenesis in this animal are induced by oestrogen [Bullough, 1942b]. Further, it appears that the growth of the follicles and corpora lutea, as well as the mitotic activity of the interstitial and connective tissue cells, are due to the action of this hormone [Bullough, 1942c].
Experiments were therefore planned to test these theories as far as possible. It has already been shown [Bullough, 1942d] that
Search for other papers by Md. Jamal Uddin in
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Search for other papers by S. Bhattacharya in
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ABSTRACT
Binding of piscine and mammalian gonadotrophin to plasma membranes from the ovaries of a fish, the murrel (Channa punctatus), clearly suggests that the fish ovary possesses distinct and specific binding sites for both piscine and mammalian gonadotrophins. Maximum specific binding of 125I-labelled human chorionic gonadotrophin (125I-hCG) and 125I-labelled silver carp gonadotrophin (125I-scG) was obtained at 30 °C and pH 7·5 during 2 h of incubation. In competitive binding studies, binding of radiolabelled scG was effectively inhibited by piscine gonadotrophins while LH and hCG had less effect and FSH showed no inhibition. By using plasma membrane preparations from kidney, skeletal muscle, brain and ovary it could be shown that specific binding of radiolabelled gonadotrophins was restricted to ovarian tissue. Binding characteristics of both 125I-scG and 125I-hCG to a preparation of murrel ovarian plasma membranes showed saturability with high affinity and low capacity. Scatchard plot analysis gave a higher dissociation constant for hCG (Kd = 235 pmol/l) than for scG (Kd= 127 pmol/l). Maximum binding capacity of scG was about twofold higher (6·27 fmol/mg protein) than that of hCG (3·76 fmol/mg protein). An increase in gonadotrophin binding resulted in a greater formation of pregnenolone from cholesterol, indicating functional relevance. At a concentration of 8 mmol/l, Ca2+ markedly inhibited the binding of gonadotrophin. The physiological importance of this inhibition is discussed.
J. Endocr. (1986) 111, 407–413
Search for other papers by ANITA M. MANDL in
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Search for other papers by S. ZUCKERMAN in
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SUMMARY
1. The ovaries of adult rats were directly X-irradiated by means of a superficial irradiation apparatus, the rest of the body being screened with lead. A dose of 4400 r produced complete sterilization. None of the animals developed radiation sickness.
2. The sterilized ovary does not undergo compensatory hypertrophy after unilateral ovariectomy, nor does it increase in size in response to exogenous gonadotrophin.
3. After irradiation, short periods of vaginal cornification recur at increasingly irregular intervals; after a minimum of 5 days and usually within 40 days, the vaginal smear becomes continuously cornified. After the period of cornification, which lasts from 2 to 14 weeks, and during which the animals will not mate, the smears become similar to those seen in spayed animals.
4. In sterilized animals the uterus is smaller than normal, but as long as 26 weeks after treatment is still significantly larger than that of spayed controls.
5. These indications of oestrogenic effects continue after bilateral adrenalectomy. They cease after removal of the X-ray sterilized ovaries.
6. Changes in the weight of the body, thymus and spleen after X-irradiation are similar to, but less rapid than, those occurring after ovariectomy. The increase in the weight of the pituitary is greater than that after ovariectomy. The adrenal glands do not decrease in size, as they do after bilateral ovariectomy.
7. The pituitaries of X-ray sterilized animals contain more gonadotrophin than do those of control-operated litter-mates, and about the same amount as do those of spayed rats.
Search for other papers by AM Holland in
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The kallikreins (KLKs) are a highly conserved multi-gene family of serine proteases that are expressed in a wide variety of tissues and act on a diverse range of substrates. KLK-like enzyme activity has variously been reported to increase or decrease during the period leading up to ovulation in the equine chorionic gonadotrophin (eCG)primed, human chorionic gonadotrophin (hCG)-stimulated immature rat ovary. These earlier studies, which used biochemical assays to detect enzyme activity, lacked the specificity and sensitivity necessary to characterise conclusively the activity of the individual KLK gene family members. In this study, we have used a gene-specific RT-PCR/Southern hybridisation strategy to delineate the expression patterns of six of the individual KLK genes expressed in the rat ovary (rKLK1-3 and rKLK7-9). We have identified three broad patterns of expression in the eCG/hCG-stimulated ovary in which there is either a post-eCG increase/pre-ovulatory decrease in rKLK expression (rKLK1, rKLK3), a peri-ovulatory decrease in expression (rKLK2, rKLK8) or a relatively unchanged pattern of expression (rKLK7, rKLK9). In addition to clarifying the earlier biochemical studies, these findings support a differential role for the individual KLKs in the ovulatory process.
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Search for other papers by M. E. Cruz in
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Search for other papers by R. Domínguez in
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ABSTRACT
The possible existence of peripheral asymmetry in the neuroendocrine mechanisms participating in the response of the ovary to gonadotrophins, and the participation of the vagus nerve, was investigated. At oestrus, the ovulation rate (number of ovulating/number of treated rats) of the left ovary in right unilaterally ovariectomized rats was lower than that in the right ovary in left unilaterally ovariectomized rats (42 vs 84%). No differences in the number of ova shed per ovulating animal nor in compensatory ovarian hypertrophy (COH) were observed. Bilateral section of the vagus nerve resulted in reduced COH only in those animals with the left ovary in situ (right unilaterally ovariectomized). Section of the left vagus nerve induced different effects depending upon which ovary was left in situ. When the left ovary was in situ an increase in ovulation rate, COH and number of ova shed was observed; however, when the right ovary was left in place the above three parameters decreased. Section of the right vagus nerve produced a decrease only in COH in both right and left unilaterally ovariectomized animals. It is concluded that in the unilaterally ovariectomized rat the right ovary seems more able to react to compensatory regulatory systems than does the left. The character of the information carried by the left and right vagus nerve is different.
J. Endocr. (1987) 113, 397–401
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Search for other papers by S G Hillier in
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Abstract
Androgen receptor (AR) distribution and developmental regulation in the rat ovary were examined by semiquantitative immunohistochemistry. Ovarian AR mRNA levels were also determined by Northern analysis of total RNA and compared with the levels of cytochrome P450aromatase (P450arom), an established marker of preovulatory follicular maturity. Hypophysectomized immature female rats were treated with recombinant human (rh)-FSH and/or rh-LH, or human menopausal gonadotrophin (HMG). AR was predominately located in granulosa cells. There was no indication of specific AR immunoreactivity in thecal cells, but scattered stromal cells did stain positively. In control and LH-treated ovaries, only small preantral/early antral follicles were present. Granulosa cells in these follicles showed intense AR immunostaining. Treatment with FSH, FSH and LH or HMG stimulated varying degrees of preovulatory follicular development. In these follicles, the intensity of AR immunostaining progressively declined as follicular development progressed. In intact immature rats treated with FSH, the abundance of ovarian AR mRNA was significantly decreased to 35% of the control value while combined treatment of FSH and LH resulted in further down-regulation of AR mRNA expression to 17% of the control value. A decrease in the abundance of AR mRNA was accompanied by a simultaneous increase in the abundance of P450arom mRNA. Similar results were obtained in hypophysectomized immature rats treated with FSH and LH, suggesting an inverse relationship between AR mRNA expression and granulosa cell maturity. These results suggest that (1) the AR is most abundant in the granulosa cells of rat ovaries and (2) the expression of AR and its mRNA are developmentally regulated, being down-regulated during FSH-stimulated preovulatory follicular development.
Journal of Endocrinology (1995) 145, 535–543
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Search for other papers by R. van der Linden in
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To determine changes in steroidogenesis by rat ovaries during sexual maturation, ovaries obtained at various ages (days 10–35) and at the first pro-oestrus were incubated in the absence or presence of LH and the accumulation of steroids in the medium was measured.
Basal and LH-stimulated oestradiol-17β and testosterone release into the medium, expressed in pmol/4 h per mg ovary, was high at day 10 of age and at first pro-oestrus. Between days 20 and 35 basal oestradiol and testosterone release was low and could not be stimulated by LH. Addition of testosterone to the culture medium increased oestradiol production at all ages studied. Release of progesterone occurred at all ages even in LH-free medium. Incubation in the presence of LH resulted in a dose-dependent increase in progesterone with a maximal response at pro-oestrus. Androsterone and 5α-androstane-3α,17β-diol production in the absence or presence of LH was high during the entire prepuberal period. Production of 5α-reduced androgens in response to LH increased from days 10 to 20 but decreased thereafter. Similarly, 5α-reductase activity, measured in ovarian homogenates, increased from days 10 to 20 but was decreased again by first pro-oestrus. A further decrease in basal and LH-stimulated 5α-reduced androgen production occurred after first ovulation.
These results demonstrated age-related changes in steroid release after in-vitro incubation. At day 10 progesterone can be converted to aromatizable androgens allowing production of oestrogens, while after day 10 progesterone is converted to 5α-reduced C19 steroids. The decrease in 5α-reductase activity correlates with an increase in LH-stimulated testosterone and oestradiol production at the first pro-oestrus.
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Search for other papers by J. H. LEATHEM in
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SUMMARY
Immature female rats were fed thiouracil for 30 days and injected with 10 i.u. human chorionic gonadotrophin (HCG) for the last 20 days. In thiouracil-fed animals, HCG produced large ovaries containing follicular cysts. These ovaries showed a subnormal concentration of cholesterol but both a normal total content and normal incorporation of [1-14C]acetate into digitonin-precipitable-sterols. Liver and serum cholesterol concentrations were reduced, but in vivo, 4 hr. incorporation of acetate into sterols was doubled suggesting either an acceleration of cholesterol turnover or delayed utilization of sterol precursors of cholesterol. HCG also reduced ovarian cholesterol concentration in euthyroid animals but total organ content and incorporation of [14C]acetate were not altered, nor were liver and serum cholesterol affected. Since the effect of induced ovarian cysts on sterol metabolism cannot be accounted for by known effects of thyroid or gonadal hormones it is suggested that influences of steroid hormones on lipid metabolism may be greatly modified in thyroid deficiency.
