Influence of progesterone receptors deficit in early stage of development on formation of the reproduction functions of female rats

The effects of 100 mg/kg mifepristone administration from 1 to 5 postnatal days on formation of the female reproduction functions were studied. It has been shown that neonatal blockade of progesterone receptors resulted in significant decline of morphometric parameters of the adult rat uterus, as well as disturbance sex steroids secretion and decrease density of uterus progesterone receptors in the oestrus. Neonatal administration of mifepristone did not change the rat ability to reproduction in favorable condition, but induced significant fetus resorption under the gestation pathology. These data suggest that violation of progesterone receptors mechanisms in neonatal period of life exert negative influence on the female reproduction functions in adult. We suggest, that neonatal treatment of mifepristone can been used as a model of progesterone receptors deficit in the adult rat uterus.     

Influence of 50 Hz magnetic field on sex hormones and body, uterine, and ovarian weights of adult female rats

The effects of extremely low-frequency (ELF) magnetic fields on sex hormones of adult female Spague-Dawley rats were investigated. Adult female rats were exposed to a 50 Hz sinusoidal magnetic field at approximately 25 microT (rms) for 18 weeks before they returned to their normal life with unexposed counterparts. Serum level of Luteinizing Hormone (LH), Follicle Stimulating Hormone (FSH), progesterone, and estrogen were measured before, after, and during the exposure. Body and uterine weights were not affected by the field. A significant reduction in absolute and relative ovarian weights in exposed rats was observed when compared with sham-exposed controls (P < 0.05). The reduction in the levels of gonadotropins (FSH and LH) was significant after six weeks of exposure (P < 0.005). FSH levels were affected only on week 6 of exposure while LH remained affected during at 12 and 18 weeks (P < 0.05). Interestingly, no significant effects were found at 6 and 12 weeks after removing the field. The level of progesterone and estrogen was significantly decreased after 12 weeks of exposure (P < 0.05), while no other effects on progesterone level was observed during exposure or after removing the exposure. The level of estrogen was also significantly reduced at 12 weeks after removing the field (P < 0.05). These results suggest possible adverse effect on mammalian fertility and reproduction. The effects of ELF-MF on sex hormones were shown to be partly reversible.     

Effects of deletion of the prolactin receptor on ovarian gene expression

Prolactin (PRL) exerts pleiotropic physiological effects in various cells and tissues, and is mainly considered as a regulator of reproduction and cell growth. Null mutation of the PRL receptor (R) gene leads to female sterility due to a complete failure of embryo implantation. Pre-implantatory egg development, implantation and decidualization in the mouse appear to be dependent on ovarian rather than uterine PRLR expression, since progesterone replacement permits the rescue of normal implantation and early pregnancy. To better understand PRL receptor deficiency, we analyzed in detail ovarian and corpora lutea development of PRLR-/- females. The present study demonstrates that the ovulation rate is not different between PRLR+/+ and PRLR-/- mice. The corpus luteum is formed but an elevated level of apoptosis and extensive inhibition of angiogenesis occur during the luteal transition in the absence of prolactin signaling. These modifications lead to the decrease of LH receptor expression and consequently to a loss of the enzymatic cascades necessary to produce adequate levels of progesterone which are required for the maintenance of pregnancy.     

The orphan receptor COUP-TFII regulates G2/M progression of breast cancer cells by modulating the expression/activity of p21(WAF1/CIP1), cyclin D1, and cdk2

The orphan receptors COUP-TFI and COUP-TFII play an important role in development and differentiation by activating specific genes and by modulating the activity of nuclear receptors including estrogen receptor alpha (ERalpha) and retinoic acid receptors (RARs). Previously, it was demonstrated that the expression and activity of ERalpha and RARs are lost or impaired in anti-estrogen-resistant breast cancers. Here we show that, similar to ERalpha and RARs, the expression of COUP-TFII but not COUP-TFI is reduced in approximately 30% of breast cancer cell lines. Introduction of COUP-TFII to MDA-MB-435 cells resulted in reduced growth and plating efficiency. Interestingly, COUP-TFII increased the expression of cyclin D1 and p21(WAF1/CIP1) in MDA-MB-435 cells. Although parental and COUP-TFII-transduced cells progressed through the G1-S phase at a similar rate, progression of COUP-TFII cells through the G2/M transition phase was delayed. The activity of cdk2 required for G2/M progression was reduced in COUP-TFII cells compared to parental cells. This property of COUP-TFII is distinct from that of ERalpha and RARs, which usually modulate the G1 phase of breast cancer cells. Furthermore, these results reveal an important physiological function of COUP-TFII, which correlates with its ability to induce gene expression rather than modulation of nuclear receptor activity.     

The role of the pituitary in modifications of the uterine secretion of spayed, oestradiol-primed rats

Tests performed on spayed, adult female estradiol-primed Ivanovas rats, with ligated uteri and normal pituitary function have shown that treatment with sexual steroids, including progesterone and testosterone, modifies uterine secretion. One half of the animals were hypophysectomized. In estradiol primed hypophysectomized controls, growth was retarded about 28%, the weight of the empty uterus reduced, and the quantity of uterine secretion diminished in comparison with the values for the nonhypophysectomized controls. In test rats treated with estradiol, gain in body weight was virtually arrested in the nonhypophysectomized rats and a reduction in weight was observed in both groups treated with the highest dose of estradiol tested (300 mcg/kg daily). In rats treated with progesterone, no significant differences were found between the two groups. In treated groups, a dose-related reduction in the weight of the empty uterus was found. Treatment caused a marked reduction in the quantity of the uterine secretion, the effect appearing greater in nonhypophysectomized rats. Increasing doses of progesterone produced a rapid rise in the viscosity of the uterine fluid, as well as a decrease in the pH of the uterine lumen. In both hypophysectomized and nonhypophysectomized rats, testosterone induced a dose-related increase in body weight, statistically significant only in animals with intact pituitaries treated with 100 mg/kg daily. The weight of the empty uterus also increased. The quantity of uterine fluid was reduced by testosterone only when it was given in massive doses to nonhypophysectomized rats. Doses of 100-300 mg/kg daily were needed to produce the same response as a dose of about 10 mg/kg daily of progesterone. In response to large doses, viscosity of secretion rose slightly and the pH of uterine lumen and secretion decreased. It may be concluded that the progestative modifications induced by progesterone in the uterus of spayed, estradiol-primed rats, including particularly changes in uterine secretion, are the effects of a peripheral mechanism not involving the pituitary. Testosterone appears to be an exception as far as the quantity and viscosity of uterine secretion are concerned, since modifications in these parameters are only observed in the presence of a functional pituitary body.     

Molecular mechanisms involved in progesterone receptor regulation of uterine function

The ovarian steroid hormone progesterone is a major regulator of uterine function. The actions of this hormone is mediated through its cognate receptor, the progesterone receptor, Pgr. Ablation of the Pgr has shown that this receptor is critical for all female reproductive functions including the ability of the uterus to support and maintain the development of the implanting mouse embryo. High density DNA microarray analysis has identified direct and indirect targets of Pgr action. One of the targets of Pgr action is a member of the Hedgehog morphogen Indian Hedgehog, Ihh. Ihh and members of the Hh signaling cascade show a coordinate expression pattern in the mouse uterus during the preimplantation period of pregnancy. The expression of Ihh and its receptor Patched-1, Ptc1, as well as, down stream targets of Ihh-Ptch1 signaling, such as the orphan nuclear receptor COUP-TF II show that this morphogen pathway mediates communication between the uterine epithelial and stromal compartments. The members of the Ihh signaling axis may function to coordinate the proliferation, vascularization and differentiation of the uterine stroma during pregnancy. This analysis demonstrates that progesterone regulates uterine function in the mouse by coordinating the signals from the uterine epithelium to stroma in the preimplantation mouse uterus.     

Perigestational suppression of weight gain with central leptin gene therapy results in lower weight F1 generation

The efficacy of central leptin therapy on weight homeostasis through various phases of reproduction, pregnancy outcome and postnatal, prepubertal and pubertal growth of offspring was assessed. Enhanced leptin transgene expression after a single intracerebroventricular injection of recombinant adeno-associated virus vector encoding the leptin gene (rAAV-lep) decreased calorie intake and weight in adult nulliparous female rats. rAAV-lep treated rats conceived normally, displayed unremarkable pregnancy rate, parturition and delivered normal sized litters. Significantly lower weight was maintained through gestation, lactation, and post-lactation periods. The maintenance of a modest weight reduction was accompanied by voluntarily reduced calorie intake, increased thermogenic energy expenditure, decreased adiposity as reflected by drastically reduced leptin levels, and suppressed insulin and insulin-like growth factor 1 levels through lactation and post-lactation in rAAV-lep treated dams. The offspring at birth weighed significantly less than those of controls and this lower weight range was sustained during postnatal, prepubertal, pubertal and adult (3 months old) periods, contemporaneous with metabolic circulating hormones in the normal range. For the first time we show the persistent efficacy of central leptin gene therapy to suppress weight gain through all phases of reproduction, lactation and post-lactation in dams and reveal the potential imprinting link to producing lower weight in the F1 generation.     

Connective tissue growth factor is required for normal follicle development and ovulation

Connective tissue growth factor (CTGF) is a cysteine-rich protein the synthesis and secretion of which are hypothesized to be selectively regulated by activins and other members of the TGF-β superfamily. To investigate the in vivo roles of CTGF in female reproduction, we generated Ctgf ovarian and uterine conditional knockout (cKO) mice. Ctgf cKO mice exhibit severe subfertility and multiple reproductive defects including disrupted follicle development, decreased ovulation rates, increased numbers of corpus luteum, and smaller but functionally normal uterine horns. Steroidogenesis is disrupted in the Ctgf cKO mice, leading to increased levels of serum progesterone. We show that disrupted follicle development is accompanied by a significant increase in granulosa cell apoptosis. Moreover, despite normal cumulus expansion, Ctgf cKO mice exhibit a significant decrease in oocytes ovulated, likely due to impaired ovulatory process. During analyses of mRNA expression, we discovered that Ctgf cKO granulosa cells show gene expression changes similar to our previously reported granulosa cell-specific knockouts of activin and Smad4, the common TGF-β family intracellular signaling protein. We also discovered a significant down-regulation of Adamts1, a progesterone-regulated gene that is critical for the remodeling of extracellular matrix surrounding granulosa cells of preovulatory follicles. These findings demonstrate that CTGF is a downstream mediator in TGF-β and progesterone signaling cascades and is necessary for normal follicle development and ovulation.