Progesterone Receptor Immunoreactivity Research Articles

Long-term use of oral contraceptives increases the risk of miscarriage

In this prospective, case-control study, a step-wise logistic regression model was used to examine the relationship between the consumption of oral contraceptives before pregnancy and the potential increase in the risk of miscarriage. Consumption of oral contraceptives for more than 2 years before pregnancy is associated with a higher risk of miscarriage.

Leukocyte Populations and Steroid Receptor Expression in Human First-Trimester Decidua; Regulation by Antiprogestin and Prostaglandin E Analog

Progesterone acting via its cognate receptor is critical to maintaining a viable endometrial environment for implantation and pregnancy. During medical termination of pregnancy, the biological effect of progesterone is pharmacologically withdrawn and prostaglandins administered exogenously. Leukocytes within the uterus are the effector cells of an inflammatory response and play important roles in both tissue breakdown and remodeling. The aim of this study was to identify the separate and combined effects of the antiprogestin Mifepristone (single dose, 200 mg) and the prostaglandin E (PGE) analog (gemeprost) on leukocyte populations and steroid receptor expression in human first-trimester decidua. Eighty women were recruited from the termination of pregnancy service with a gestational age of between 35 and 65 d at the time of surgical termination of pregnancy. Immunohistochemistry was used to measure macrophage (CD68 +ve), neutrophil (neutrophil elastase +ve), and uterine natural killer cell (CD56 +ve) populations and progesterone (PR(A) and PR(B)), estrogen (ERalpha and ERbeta), and androgen receptor (AR) expression. After administration of both antiprogestin and the PGE analog, macrophage and neutrophil numbers were significantly increased, whereas natural killer cell numbers were unchanged. Antiprogestin and PGE analog coadministration also significantly decreased PR and ERalpha immunoreactivity but had no effect on androgen receptor or ERbeta receptor expression. PGE analog alone was also capable of reducing PR expression. In this study, we demonstrate that the inflammatory response induced by antiprogestin in combination with PGE analog is accompanied by both increases in macrophages and neutrophils numbers and decreases in PR and ERalpha expression in human first-trimester decidua.

Mammary pseudoangiomatous stromal hyperplasia presenting as an axillary mass

Pseudoangiomatous stromal hyperplasia (PASH) of the breast is characterized by interanastomosing slit-like spaces lined with spindle-shaped cells in an abundant fibrous stroma. PASH is a relatively common incidental finding in the breast tissue removed for other reasons and rarely presents as a localized mass. The etiology of PASH is unknown, but hormonal factors are thought to be involved. Accessory breast tissue is subject to all pathologic changes found in the normal breast. We report a case of PASH that presented as a palpable axillary mass in a 43-year-old woman. To our knowledge, PASH has not previously been reported in the axillary accessory breast tissue. The spindle stromal cells in our patient showed immunophenotypic characteristics of myofibroblastic differentiation. Immunoreactivity for progesterone receptor was noted in the spindle cells. These findings support the hypothesis that endogenous hormones are involved in the development of PASH.

Stress-induced progesterone secretion and progesterone receptor immunoreactivity in the paraventricular nucleus are modulated by pubertal development in male rats

Male rats show a differential adrenocortical response to stress before and after pubertal development, such that prepubertal animals have a more prolonged stress-induced corticosterone response compared to adults. Whether pubertal maturation affects other adrenocortical responses to stress is currently unknown. To address this question, we assessed stress-induced progesterone secretion in both intact and gonadectomized prepubertal (28 days of age) and adult (77 days of age) male rats either before or after exposure to a 30 min session of restraint stress. We found that prepubertal males show a greater and more prolonged stress-induced progesterone response compared to adults. We also found a similar effect in castrated prepubertal and adult males, indicating the differential stress-induced progesterone response is not gonadal in origin. We also examined progesterone receptor (PR) levels by immunohistochemistry in the paraventricular nucleus (PVN) of the hypothalamus, a key regulatory nucleus of the hypothalamic–pituitary–adrenal (HPA) axis, and found lower PR protein expression in the PVN of prepubertal compared to adult males. These data indicate that in addition to corticosterone, stress-induced adrenocortical progesterone levels are differentially affected by pubertal maturation. Furthermore, these data raise the possibility of different progesterone sensitivity of the PVN before and after puberty. The significance of this differential response is presently unknown. However, given the pleiotropic effects of progesterone on male physiology and behaviour, it is likely that the disparate post-stress exposure to progesterone affects the prepubertal and adult male differently.

Gonadotrope oestrogen receptor-α and -β and progesterone receptor immunoreactivity after ovariectomy and exposure to oestradiol benzoate, tamoxifen or raloxifene in the rat: correlation with LH secretion

The selective oestrogen receptor modulator (SERM) tamoxifen (TX) has agonist/antagonist actions on LH secretion in the rat. Whereas in the absence of oestrogens TX elicits progesterone receptor (PR)-dependent GnRH self-priming, it antagonizes oestrogen-stimulatory action on LH secretion. The aim of these experiments was to explore whether TX treatment-induced differential expression of oestrogen receptor (ER)alpha and ERbeta in the gonadotrope may determine its agonist effect on LH secretion. In the first experiment, basal LH secretion, GnRH-stimulated LH secretion and PR-dependent GnRH self-priming were determined in incubated pituitaries from ovariectomized (OVX) rats treated with oestradiol benzoate (EB), TX or raloxifene (RX). Cycling rats in metoestrus or pro-oestrus were used as basic controls. As in pro-oestrus, pituitaries from OVX rats treated with EB exhibited GnRH-stimulated LH secretion, immunohistochemical PR expression and GnRH self-priming. While RX had no effect on these parameters, TX induced PR expression and GnRH self-priming. GnRH self-priming was absent in pituitaries incubated with the antiprogestin ZK299. In the second experiment, we evaluated the immunohistochemical expression of ERalpha and ERbeta in gonadotropes of cycling rats and OVX rats treated with EB, TX or RX. We found that while ERalpha expression was similar in all six groups, ERalpha expression was oestrous cycle dependent. Moreover, ERalpha expression in gonadotropes of TX-treated rats was as high as that found in pro-oestrus, while ERalpha expression in the gonadotropes of RX-treated rats was lower than in metoestrous or pro-oestrous pituitaries. These results suggest that, in the absence of the cognate ligand, TX, unlike RX, may regulate LH secretion through the ERalpha subtype in gonadotropes.

Estrogen and Progesterone Receptor Expression in Uterine and Extrauterine Leiomyosarcomas

The authors have noted anecdotal cases of extrauterine leiomyosarcomas (LMS) with estrogen receptor (ER) and progester-one receptor (PR) immunoreactivity. However, there are few studies that have compared ER and PR immunoexpression in LMS of uterine and extrauterine origin. The authors obtained a representative formalin-fixed, paraffin-embedded tissue block from cases of uterine LMS (n = 15) and extrauterine LMS (n = 16) from the archives of the Cleveland Clinic Foundation and performed immunohistochemical staining for ER and PR. Staining was evaluated by 2 observers in a semiquantitative manner using the following scale: 0, no nuclear staining; 1+, 1 to 25% of nuclei stained; 2+, 26 to 50% of nuclei stained; 3+, 51 to 75% of nuclei stained; 4+, 76 to 100% of nuclei stained. The majority of uterine LMS stained for ER (13 of 15, 87%), PR (12 of 15, 80%), or both ER and PR (12 of 15, 80%), with most cases showing 3+ or 4+ positive staining. For the extrauterine LMS cases, staining for ER was seen in 4 of 16 cases (25%), staining for PR was observed in 2 of 16 cases (13%), and staining for both ER and PR was seen in 2 of 16 cases (13%). One extrauterine LMS showed 4+ coexpression of ER and PR, but the remaining extrauterine cases showed only 1+ ER and/or PR immunoreactivity. These data suggest that most uterine LMS coexpress ER and PR, and most extrauterine LMS do not stain for these antigens. However, a subset of extrauterine LMS are ER and/or PR immunoreactive. This raises the possibility that hormonal manipulation may be beneficial in the treatment of these therapeutically recalcitrant tumors.

Estrogen receptor, progesterone receptor, and bcl-2 are markers with prognostic significance in CIN III.

There are no known biological markers or technologies to predict the natural history of an individual CIN III. The probability of progression is considered greater with the persistence of high-risk human papillomavirus (HPV) infection and age. p53 polymorphism has been associated with cervical carcinogenesis. Hormone-induced cervical cancer is mediated by estrogen receptor (ER) and progesterone receptor (PR). In cervical cancer, increased bcl-2 and Bax immunoreactivity is generally associated with a better prognosis. The purpose of this study was to evaluate the value of HPV 16 and HPV 18 typing and p53 codon polymorphism genotyping by polymerase chain reaction and ER, PR, bcl-2, and Bax expression by immunohistochemistry in predicting the CIN III clinical behavior of CIN III lesions. We studied the expression of these prognostic factors in the CIN III adjacent to squamous cell microinvasive carcinomas of the cervix (MIC) from 29 patients with FIGO stage IA1 cervical cancer and in 25 patients with CIN III and no documented focus of invasion. In the MIC group, only the CIN III was considered at least 2 mm away from the microinvasive complex. The ER, PR, bcl-2, and Bax immunoreactivity was scored as positive (>10% staining cells) and negative (<10% staining cells). No significant difference was observed between MIC and CIN III group concerning HPV infection and p53 polymorphism. The ER, PR, bcl-2, and Bax immunohistochemical expression was stronger and more frequent in the CIN III group. After multivariable analysis, coexpression of ER, PR, and bcl-2 was the only independent factor in defining low risk of progression for CIN III. Our study suggests that coexpression of ER, PR, and bcl-2 may be a useful tool in identifying the CIN III lesions with low risk of progression to cervical cancer.

Estrogen receptor, progesterone receptor, and bcl-2 are markers with prognostic significance in CIN III

There are no known biological markers or technologies to predict the natural history of an individual CIN III. The probability of progression is considered greater with the persistence of high-risk human papillomavirus (HPV) infection and age. p53 polymorphism has been associated with cervical carcinogenesis. Hormone-induced cervical cancer is mediated by estrogen receptor (ER) and progesterone receptor (PR). In cervical cancer, increased bcl-2 and Bax immunoreactivity is generally associated with a better prognosis. The purpose of this study was to evaluate the value of HPV 16 and HPV 18 typing and p53 codon polymorphism genotyping by polymerase chain reaction and ER, PR, bcl-2, and Bax expression by immunohistochemistry in predicting the CIN III clinical behavior of CIN III lesions. We studied the expression of these prognostic factors in the CIN III adjacent to squamous cell microinvasive carcinomas of the cervix (MIC) from 29 patients with FIGO stage IA1 cervical cancer and in 25 patients with CIN III and no documented focus of invasion. In the MIC group, only the CIN III was considered at least 2 mm away from the microinvasive complex. The ER, PR, bcl-2, and Bax immunoreactivity was scored as positive (&gt;10% staining cells) and negative (&lt;10% staining cells). No significant difference was observed between MIC and CIN III group concerning HPV infection and p53 polymorphism. The ER, PR, bcl-2, and Bax immunohistochemical expression was stronger and more frequent in the CIN III group. After multivariable analysis, coexpression of ER, PR, and bcl-2 was the only independent factor in defining low risk of progression for CIN III. Our study suggests that coexpression of ER, PR, and bcl-2 may be a useful tool in identifying the CIN III lesions with low risk of progression to cervical cancer.

Effect of plane of nutrition on endometrial sex steroid receptor expression in ewes

The effect of plane of nutrition on progesterone receptor (PR) and estrogen receptor α (ERα) expression in ovine endometrium was investigated. Rasa Aragonesa ewes ( n=26) were fed diets to provide either 1.5 (Group C) or 0.5 (Group L) times the daily maintenance requirement and were slaughtered at Days 5 or 10 of the estrous cycle (Day 0=estrus). PR and ERα immunoreactivity were analyzed in eight endometrial cell compartments, defined by cell type and location. Group L had less PR immunostaining on Day 5 ( P<0.05), which is consistent with lesser endometrial content of progesterone found in such animals. Most cell types of Group C had down regulation of PR at Day 10, but in Group L, this pattern was observed only in three cell compartments. The lesser PR contents found at Day 5 in Group L ewes may explain the lack of inhibition of PR. No effect of treatment or day of the estrous cycle was observed in ERα. Results indicate that endometrial PR is affected in a cell type, in specific manner, by plane of nutrition.

Neonatal mice possessing an Sry transgene show a masculinized pattern of progesterone receptor expression in the brain independent of sex chromosome status.

To assess the relative roles of sex chromosome genes and gonadal steroid hormones in producing sex differences in progesterone receptor (PR) expression in the forebrain of neonatal mice, we used mice in which the Sry gene had been deleted from the Y-chromosome and inserted as a transgene on an autosome in both XX and XY genotypes. Levels of PR immunoreactivity (PRir) in the anteroventral periventricular nucleus, the medial preoptic nucleus, and the ventromedial nucleus were significantly higher in mice that possessed an Sry transgene compared with mice that lacked an Sry transgene, regardless of their complement of sex chromosomes (XX vs. XY). This result suggests that sexual differentiation of PR expression in these regions is likely controlled mainly by gonadal hormones, not by the genetic sex of the brain cells. No differences in PRir were detected between wild-type XY mice with the Sry gene on the Y-chromosome and XY mice with the Sry transgene, suggesting that testicular hormones produced in these two genotypes have comparable effects on neural tissue.

Evaluation of progesterone and estrogen receptor expression in 15 meningiomas of dogs and cats.

To evaluate progesterone and estrogen receptor expression in meningiomas of the CNS in dogs and cats. 8 dogs (1 of which was treated with gestrinone) and 5 cats with intracranial meningiomas and 2 dogs with spinal cord meningiomas; tissue samples were also obtained from 1 clinically normal dog and 1 clinically normal cat. Meningioma tissue was obtained during surgery or at necropsy; samples were processed for histologic classification and immunohistochemical evaluation of the proportion of tumor cells with progesterone and estrogen receptors. Correlation among receptor expression, tumor grade, and histologic subtypes was determined. Several histologic subtypes of intracranial meningiomas were detected among tissue samples. In the cats, all intracranial meningiomas were benign. Progesterone receptor immunoreactivity was detected in 14 of 15 meningiomas. Progesterone receptor expression was identified in > 80% of cells in 8 intracranial meningiomas (4 dogs and 4 cats) and 2 spinal cord meningiomas. In samples of malignant transitional and granular cell meningiomas in dogs, progesterone receptors were detected in 32 and 4.8% of cells respectively. In 1 cat, 38% of tumor cells had progesterone receptors. In a dog treated with gestrinone, no progesterone receptors were detected in the intracranial meningioma. Estrogen receptors were only detected in the tumor of 1 dog. Results indicate a high proportion of progesterone receptors in cells of meningiomas of the CNS in dogs and cats. Antiprogesterone treatment may have a role in the treatment of unresectable or recurrent meningiomas in dogs and cats.

Pregnancy and breast cancer: a population-based study.

The incidence of pregnancy-associated breast cancer, i.e. during pregnancy and lactation, and of pregnancy subsequent to a breast-cancer diagnosis will increase as more women choose childbearing at a later age. Few larger series are published on pregnancy-associated breast cancer. In a population-based study, we evaluated the outcome and prognostic factors in 173 breast-cancer patients. One hundred and twenty-two patients had pregnancy-associated breast cancer (20 coincident with pregnancy and 102 during lactation) and 51 patients had pregnancy subsequent to breast cancer. The median follow-up time was 151 months. Histopathological parameters and immunoreactivity for oestrogen and progesterone receptors c-erbB-2 and c-erbB-4 were studied. All three groups had tumours with high histological grade, low frequency of hormone receptors and high expression of c-erbB-2. The pregnancy and lactation groups were near identical with regard to all histopathological parameters and outcome. In the two pregnancy-associated breast-cancer groups, tumours were significantly larger, with more extensive lymph-node involvement. For node-negative tumours the respective 5- and 10-year survival rates were 62% and 50% in the pregnancy group and 60% and 50% in the lactation group. For node-positive tumours, respective 5- and 10-year survival rates were 50% and 34% in the pregnancy group and 50% and 33% in the lactation group. In the subsequent group, overall survival was high in both node-negative and -positive groups, with 5- and 10-year survival rates of 80% and 73% and 86% and 76%, respectively. Tumour size, lymph-node status, histological grade, progesterone receptor, oestrogen receptor and c-erbB-2 were significant prognostic factors in the pregnancy-associated breast-cancer patients.

Changes in the presence of progesterone receptor isoforms in the oviduct magnum of newly-hatched chicks after gonadotropins treatment

The effects of Follicle-stimulating hormone (FSH) and Luteinizing hormone (LH) on progesterone receptor (PR) isoforms presence in different cell populations from the oviduct magnum of newly-hatched chicks treated in vivo on days 13, 15 and 17 of embryonic development, were analyzed by immunohistochemistry. We found that FSH promoted cytodifferentiation of the magnum's mucosa and increased PR immunoreactivity in all cell types of the oviduct magnum, whereas LH-treatment did not exert cytodifferentiation of magnum's mucosa, and PR immunoreactivity was only induced in some epithelial and stromal cells of the oviduct magnum. In all treatments the number of PR immunopositive cells incubated with the antibody PgR Ab-8 that recognizes both PR isoforms were significantly higher than the number of immunopositive cells incubated with antibody PgR Ab-6 that only recognizes PR-B. This suggests that PR-A should be the predominant isoform in the oviduct magnum of newly-hatched chicks treated with gonadotropins during embryonic development. We conclude that gonadotropins differentially regulate PR-A isoform presence in the oviduct magnum of newly-hatched chicks.

Bisphenol A Increases Progesterone Receptor Immunoreactivity in the Hypothalamus in a Dose‐Dependent Manner and Affects Sexual Behaviour in Adult Ovariectomized Rats

Recently, we reported that bisphenol A (BPA), an endocrine disrupter, increased progesterone receptor (PR) mRNA in the preoptic area (POA) in adult ovariectomized rats. In the present study, we examined whether BPA also induced expression of PR proteins in both the POA and the ventromedial hypothalamic nucleus (VMH), and whether those proteins were involved in the induction of sexual behaviour. Two weeks after ovariectomy, rats received a subcutaneous (s.c.) injection of BPA, 17 beta-oestradiol or vehicle. Twenty-four hours after the injection, the rats were killed and their tissues were examined by immunocytochemistry. Some rats that received a s.c. injection of BPA, E2 or vehicle alone on the day before were injected with progesterone at 15.00 h and examined for sexual behaviour 5-7 h later. As expected, injection of 10 microg E2 significantly increased the number of PR immunoreactive cells in both the POA and the VMH compared to the number after injection of vehicle alone. In both the POA and the VMH, injection of BPA at a dose of 10 mg also significantly increased the number of PR immunoreactive cells compared to the number after injection of sesame oil alone. Furthermore, BPA induced a dose-dependent increase in the number of PR immunoreactive cells in both the POA and the VMH, demonstrating that the number of PR cells was significantly increased by as little as 100 microg of BPA. Ovariectomized (OVX) rats that were primed with 10 mg of BPA, followed by 1 mg of progesterone, displayed mainly rejection behaviour, but not lordosis as typically observed in OVX rats primed with E2 followed by progesterone. The present study suggests that BPA influences reproductive functions, including sexual behaviour even in adulthood, by altering the PR system in the hypothalamus.

Sex differences in progesterone receptor expression: a potential mechanism for estradiol-mediated sexual differentiation.

The differential exposure of males and females to testosterone (T) and its metabolite estradiol (E) contributes to the development of sex differences in the brain. However, the mechanisms by which T and E permanently alter neural development remain virtually unknown. Two regions of the rat preoptic area, the anteroventral periventricular nucleus (AVPv) and the medial preoptic nucleus (MPN), are sexually dimorphic and serve as models for studying the hormonal mechanisms of sexual differentiation. Around birth, these regions express dramatically higher levels of progesterone receptor immunoreactivity (PRir) in males than they do in females. The present study examined the possibility that sexually dimorphic induction of PR expression in these two regions constitutes a potential mechanism of E-mediated sexual differentiation. Prenatal exposure to either T propionate or the synthetic estrogen, diethylstilbestrol, but not dihydrotestosterone propionate, significantly increased PRir levels in the MPN and AVPv of fetal females compared with controls. Prenatal exposure to the aromatase inhibitor, 1,4,6-androstatriene-3,17-dione, significantly reduced PRir in the MPN and AVPv of fetal males, whereas the androgen receptor antagonist flutamide had no effect. This suggests that aromatization of T into E is crucial for the sex difference in PR expression in the MPN and AVPv during development.

Effect of estrogens on ontogenetic expression of progesterone receptor in the fetal female rat reproductive tract

Ontogenetic expression of progesterone receptor (PR) and effect of estrogens on PR expression in the fetal female rat reproductive tract were investigated. To evaluate ontogenetic PR expression, female reproductive tract from untreated fetuses was examined on gestational days (GD) 15.5, 17.5, 19.5 and 21.5. To evaluate estrogen effects, pregnant rats were injected once per day with oil, 17β-estradiol (E 2) or diethylstilbestrol (DES) from GD15 through 21. Female fetuses were prepared for real-time reverse-transcription polymerase chain reaction (RT-PCR) or immunohistochemistry for PR. Increase in PR mRNA expression was detected in the Müllerian duct on GD21.5 compared to that on GDs15.5 and 17.5 in untreated fetuses ( P<0.05). Prenatal administration of E 2 or DES increased Müllerian PR mRNA levels by GD21.5 compared with oil controls ( P<0.01). To identify cell and region in which PR was expressed and up-regulated by E 2 and DES, localization was evaluated within three regions along the Müllerian duct axis which differentiate into oviduct, uterus and upper vagina in immunohistochemistry. In untreated fetuses, Müllerian epithelial PR immunoreactivity was weak on GDs15.5 and 17.5, but then became moderate on GDs 19.5 and 21.5 in all three regions. These fetuses exhibited faint signals in Müllerian mesenchymal PR immunoreactivity during gestational monitoring. Critically, Müllerian mesenchymal PR staining became intense after E 2 exposure in all three regions by GD21.5, but no change was observed in Müllerian epithelial PR. Similarly, DES dramatically induced Müllerian mesenchymal PR in all regions by GD21.5, and also enhanced proximal epithelial PR. On the other hand, middle and caudal epithelial PRs were reduced by DES. These affected mesenchymal and epithelial cells by DES were ERα immunopositive in the Müllerian duct, except for middle Müllerian epithelium. These findings clearly demonstrate cell-specific PR localization and region-specific effect of DES on PR in the developing rat Müllerian duct, and provide fundamental information critical for investigating the tissue-specific mechanisms underlying the prenatal response to estrogen receptor agonists.

Progesterone and oestrogen receptor immunoreactivity in the vagina of the immature ostrich, Struthio camelus

1. The presence of sperm storage tubules in the cranial, middle and caudal regions of the vagina in the immature ostrich was studied. In addition, progesterone and oestrogen receptor immunoreactivity in these regions was investigated. 2. Sperm storage tubules were observed only in birds with active ovaries. Progesterone receptor immunoreactivity was more intense in birds with active ovaries, whilst immunostaining for the oestrogen receptor was absent in birds with both active and inactive ovaries. 3. These results suggest that steroid hormones produced by the active ovary mediate the activation of the progesterone receptor.

FSH and LH induce progesterone production and progesterone receptor synthesis in cumulus cells: a requirement for meiotic resumption in porcine oocytes.

The aim of this study was to investigate the role of progesterone in the meiotic resumption of porcine oocytes. Progesterone production and progesterone receptor (PR) immunoreactivity in cumulus cells were not detected in porcine cumulus-oocyte complexes (COC) when observations were made either just after collection from the follicles or after 28 h cultivation without LH and FSH. However, the addition of LH and FSH induced PR expression in cumulus cells, concomitant with increased progesterone production. To assess the role of progesterone in the COC, an inhibitor of progesterone production, aminoglutethimide (AGT), was administered. The addition of AGT to the medium with LH and FSH significantly suppressed progesterone production in a dose-dependent fashion. When COC were cultured with LH, FSH and 0.5 x 10(-3) mol/l AGT, almost complete inhibition of progesterone production and of germinal vesicle breakdown (GVBD) was seen. However, this inhibitory effect on GVBD was overcome by additional progesterone. Moreover, 0.5 x 10(-3) mol/l AGT also suppressed the reduction in connexin43, a gap junctional protein, in cumulus cells after 28 h cultivation, and increased the level of cyclic AMP in oocytes. These results support the hypothesis that the binding of progesterone, which was secreted by LH- and FSH-stimulated cumulus cells, to its newly synthesized receptor induces GVBD in porcine oocytes, possibly through a reduction of connexin43 in cumulus cells.

Progestin receptor immunoreactivity within steroid-responsive vasopressin-immunoreactive cells in the male and female rat brain.

Progestin receptor immunoreactivity is found in the same regions of the bed nucleus of stria terminalis (BST) and centromedial amygdala (CMA) as steroid-responsive vasopressin immunoreactive (AVP-ir) cells. To test whether AVP-ir cells express progestin receptors, brains of male rats were stained immunocytochemically for arginine vasopressin as well as progestin receptors. In BST and CMA, over 95% of AVP-ir cells contained progestin receptor immunoreactivity. In contrast, none of the AVP-ir cells in the suprachiasmatic, supraoptic and paraventricular nuclei expressed progestin receptor immunoreactivity. To study whether progestin receptor expression in AVP-ir cells in the BST and CMA is responsive to gonadal steroids, male and female rats were castrated and implanted with either empty capsules or capsules filled with testosterone or oestradiol, respectively. Ten days later, brains were processed for AVP and progestin receptor immunoreactivity. Although there was no effect of hormonal status on the percentage of colocalized cells, the level of progestin receptor immunoreactivity was higher in rats that received gonadal steroids than those that did not. The presence of progestin receptor immunoreactivity in steroid responsive AVP-ir cells, and the responsiveness of this expression to gonadal hormones, is consistent with the possibility that the effects of gonadal steroids on AVP-ir expression in the BST and CMA may be mediated at least in part by progestin receptors.

Progesterone receptor in the liver and oviduct of the lizard Podarcis sicula

In this paper we report the presence of a 3H-Progesterone ( 3H-P) binding moiety, which has the characteristics of a true receptor, in the liver of the female of the lizard Podarcis sicula. 3H-P binding studies show the presence of one type of binding site with an average Kd value of 6.2 ± 2.0 nM in the cytoplasm and 6.3 ± 1.1 nM in the nucleus. Competition experiments showed that progesterone (P) was the best competitor, while testosterone, deoxycorticosterone (DOC), corticosterone, 17α-hydroxyprogesterone; R5020; RU486 and RU26988-5 were poor competitors. We have also investigated the immunological characteristics of progesterone receptor (PR) in both the liver and the oviduct of Podarcis sicula, by Western blotting using the monoclonal antibody PR22 raised against the PR isoforms A and B of chicken. One imunoreactive band of about 70 kDa was detected in cytoplasmic and nuclear extracts of both the liver and the oviduct. PR immunoreactivity was present in the liver during the quiescent phase. In the oviduct PR immunoreactivity increased from the recovery to the full grown phase. P treatment of estrogen-primed females did not affect the presence of PR in the liver, while brought about a PR increase in the oviduct. This study suggests that PR is expressed differently in the liver and the oviduct of Podarcis sicula throughout the reproductive cycle. PR might fulfill different requirements in relation to the different physiological functions of the tissue during the reproductive cycle.