Localization of type 7 17beta-hydroxysteroid dehydrogenase in mouse tissues. In situ hybridization studies

The enzyme type 7 17beta-hydroxysteroid dehydrogenase (17beta-HSD) selectively catalyzes the conversion of estrone (E1) into estradiol (E2). In order to obtain detailed information about the exact sites of action of type 7 17beta-HSD, we have studied the cellular localization of type 7 17beta-HSD mRNA in mouse tissues using in situ hybridization (ISH). In parallel studies, we also measured the enzyme mRNA levels by quantitative real time (RT)-PCR. In the ovary, strong hybridization signal was restricted to corpus luteum cells. In the female mammary gland, type 7 17beta-HSD mRNA was found to be expressed in stromal cells surrounding the ducts. In the clitoral and preputial glands, specific labeling was observed in the epithelial cells of both acini and small ducts. In the adrenal gland, hybridization signal was observed in the zona fasciculata and reticularis in the cortex. In the liver, hybridization signal was found in all the hepatocytes. In the colon, type 7 17beta-HSD mRNA expression was restricted to epithelial cells of the mucosa. From the results obtained with quantitative real time RT-PCR, it appears, with a very few exceptions, that in tissues exhibiting low mRNA expression no ISH signal could be detected. The present data suggest that E2 can be formed through the action of type 7 17beta-HSD in specific cell types in the ovary and peripheral tissues, in addition to type 1 17beta-HSD, thus providing tissues with an alternative route of formation of E2.

Cellular localization of mRNA expression of enzymes involved in the formation and inactivation of hormonal steroids in the mouse prostate

It is well documented that several tissues, including the prostate, are actively involved in the local formation and inactivation of hormonal steroids. To identify the cell types involved in the formation and inactivation of androgens and estrogens in the ventral lobe prostate, we have localized by in situ hybridization (ISH) a large number of steroidogenic as well as steroid-inactivating enzyme mRNAs in the adult mouse prostate. In parallel studies, we also measured enzyme mRNA levels by quantitative real-time PCR (RT-PCR) in ventral lobe prostates. From the results obtained with quantitative RT-PCR, it appears that, with a few exceptions, the enzyme with low mRNA expression could not be detected by ISH. The following enzymes have been localized by ISH: 17beta-hydroxysteroid dehydrogenase (17beta-HSD) types 1, 2, 3, 4, 7, 8, 9, 10, and 11; 5alpha-reductase type 2; 5beta reductase type 1; P450 7alpha hydroxylase; estrogen sulfotransferase type 1; 11beta-HSD types 1 and 2; and UDP-glucuronosyltransferase 1A6. All of these mRNAs are expressed in the epithelial cells of prostatic acini. Several enzyme mRNAs were also localized in stromal cells. Types 1, 7, and 10 17beta-HSD, estrogen sulfotransferase type 1, and 11beta-HSD types 1 and 2 were found only in epithelial cells. The present results indicate that both epithelial and stromal cells in the mouse prostate play a role in local formation and inactivation of hormonal steroids.

High-energy particle acceleration in the shell of a supernova remnant

A significant fraction of the energy density of the interstellar medium is in the form of high-energy charged particles (cosmic rays). The origin of these particles remains uncertain. Although it is generally accepted that the only sources capable of supplying the energy required to accelerate the bulk of Galactic cosmic rays are supernova explosions, and even though the mechanism of particle acceleration in expanding supernova remnant (SNR) shocks is thought to be well understood theoretically, unequivocal evidence for the production of high-energy particles in supernova shells has proven remarkably hard to find. Here we report on observations of the SNR RX J1713.7 - 3946 (G347.3 - 0.5), which was discovered by ROSAT in the X-ray spectrum and later claimed as a source of high-energy gamma-rays of TeV energies (1 TeV = 10(12) eV). We present a TeV gamma-ray image of the SNR: the spatially resolved remnant has a shell morphology similar to that seen in X-rays, which demonstrates that very-high-energy particles are accelerated there. The energy spectrum indicates efficient acceleration of charged particles to energies beyond 100 TeV, consistent with current ideas of particle acceleration in young SNR shocks.

Localization of sex steroid receptors in human skin

Sex steroid hormones are involved in regulation of skin development and functions as well as in some skin pathological events. To determine the sites of action of estrogens, androgens and progestins, studies have been performed during the recent years to accurately localize receptors for each steroid hormone in human skin. Androgen receptors (AR) have been localized in most keratinocytes in epidermis. In the dermis, AR was detected in about 10% of fibroblasts. In sebaceous glands, AR was observed in both basal cells and sebocytes. In hair follicles, AR expression was restricted to dermal papillar cells. In eccrine sweat glands, only few secretory cells were observed to express AR. Estrogen receptor (ER) alpha was poorly expressing, being restricted to sebocytes. In contrast, ERbeta was found to be highly expressed in the epidermis, sebaceous glands (basal cells and sebocytes) and eccrine sweat glands. In the hair follicle, ERbeta is widely expressed with strong nuclear staining in dermal papilla cells, inner sheath cells, matrix cells and outer sheath cells including the buldge region. Progesterone receptors (PR) staining was found in nuclei of some keratinocytes and in nuclei of basal cells and sebocytes in sebaceous glands. PR nuclear staining was also observed in dermal papilla cells of hair follicles and in eccrine sweat glands. This information on the differential localization of sex steroid receptors in human skin should be of great help for future investigation on the specific role of each steroid on skin and its appendages.

Localization of 17beta-hydroxysteroid dehydrogenase type 1 mRNA in mouse tissues

The enzyme 17beta-hydroxysteroid dehydrogenase (17beta-HSD) type 1 catalyzes the conversion of estrone (E1) into 17beta estradiol (E2). To gain information about the cellular localization of 17beta-HSD mRNA type 1 expression, we performed in situ hybridization using a 35S-labeled cRNA probe in several tissues of adult mice of both sexes. In the ovary, high expression was found in granulosa cells of growing follicles. No specific labeling could be observed in corpora lutea or interstitial cells. In the pituitary gland of animals of both sexes, 17beta-HSD type 1 mRNA was expressed in the intermediate lobe melanotrophs while no specific signal could be detected in the anterior or posterior lobes of the pituitary. In the prostate, 17beta-HSD type 1 mRNA was exclusively found in the epithelial cells. In both male and female mouse dorsal skin, a specific hybridization signal was seen in the sebaceous glands while the epidermis, stroma, hair follicles and sweat glands were unlabeled. In the testis, a hybridization signal was detected in germ cells of the seminiferous tubules, Leydig cells being unlabeled. The present data indicate that E2 can be formed through the action of 17beta-HSD type 1 in specific cells of the gonads and peripheral tissues. In the testes and peripheral tissues, the action of E2 is probably limited to the cells involved in its formation in an intracrine fashion.

High levels of untreated distress and fatigue in cancer patients

The purpose of the study was to assess a large representative sample of cancer patients on distress levels, common psychosocial problems, and awareness and use of psychosocial support services. A total of 3095 patients were assessed over a 4-week period with the Brief Symptom Inventory-18 (BSI-18), a common problems checklist, and on awareness and use of psychosocial resources. Full data was available on 2776 patients. On average, patients were 60 years old, Caucasian (78.3%), and middle class. Approximately, half were attending for follow-up care. Types of cancer varied, with the largest groups being breast (23.5%), prostate (16.9%), colorectal (7.5%), and lung (5.8%) cancer patients. Overall, 37.8% of all patients met criteria for general distress in the clinical range. A higher proportion of men met case criteria for somatisation, and more women for depression. There were no gender differences in anxiety or overall distress severity. Minority patients were more likely to be distressed, as were those with lower income, cancers other than prostate, and those currently on active treatment. Lung, pancreatic, head and neck, Hodgkin's disease, and brain cancer patients were the most distressed. Almost half of all patients who met distress criteria had not sought professional psychosocial support nor did they intend to in the future. In conclusion, distress is very common in cancer patients across diagnoses and across the disease trajectory. Many patients who report high levels of distress are not taking advantage of available supportive resources. Barriers to such use, and factors predicting distress and use of psychosocial care, require further exploration.

Localization of 20α-hydroxysteroid dehydrogenase mRNA in mouse brain by in situ hybridization

The enzyme 20alpha-hydroxysteroid dehydrogenase (20alpha-HSD) catalyzes the conversion of progesterone into its inactive form, 20alpha-hydroxyprogesterone. We studied the expression of 20alpha-HSD mRNA in mouse brain by in situ hybridization. 20alpha-HSD mRNA was exclusively found in neurons in cortex and hippocampus. In the cortex, the labelled cells were concentrated in the external granular layer, the external pyramidal layer and the inner granular layer. In the hippocampus, the labelling was mostly located over pyramidal cells of the CA1 layer. These results suggest that progesterone can be inactivated by 20alpha-HSD in some specific brain areas.

Localization and estrogenic regulation of androgen receptor mRNA expression in the mouse uterus and vagina

Androgen receptors (AR) are highly expressed in female reproductive organs. In order to define the possible involvement of estrogens in the regulation of AR expression in the uterus and vagina, we have studied the effect of short-term administration of 17beta-estradiol (E2) to ovariectomized adult mice on AR mRNA levels. Seven days after ovariectomy, the mice received a single injection of E2 (0.05 microg/mouse) 3, 12 or 24 h before they were killed. The levels of AR mRNA were measured in the different uterine and vaginal compartments using quantitative in situ hybridization. In the uterus, AR mRNA was expressed in the luminal and glandular epithelial cells, stromal cells and smooth muscle cells. In the vagina, AR mRNA was localized in both epithelial and stromal cells. In the uterus after ovariectomy, AR mRNA levels were decreased by 18% in the epithelial cells, 23% in the stromal cells and 50% in the myometrial cells. AR mRNA levels were completely restored as early as 3 h after E2 administration in the epithelium and stroma, and at the 12-h time-interval in the myometrium. In the vaginal epithelium, ovariectomy induced a 70% decrease in AR mRNA expression. No effect could be detected 3 h after E2 administration, while at the longest time-intervals (12 and 24 h) there was an increase in mRNA levels corresponding to 70% of the levels observed in intact animals. In the vaginal stroma, ovariectomy was responsible for a 55% decrease in mRNA levels. While no significant changes were observed at the 3-h time-interval, a complete restoration of AR mRNA levels in stromal cells could be recorded at the longest time-intervals after E2 administration. The data obtained indicated that, in adult mice, estrogens exert a positive regulation of AR mRNA expression in the different compartments of both the uterus and the vagina.

In vivo action of a new octadecaneuropeptide (ODN) antagonist on gonadotropin-releasing hormone gene expression in the male rat brain

It has been reported that several of the effects induced by octadecaneuropeptide (ODN) could be mediated by an activation of a metabotropic receptor. In order to investigate the role and mechanism of action of ODN in gonadotropin-releasing hormone (GnRH) neuron regulation, we studied the effects of the acute i.c.v. administration of ODN and of a new ODN antagonist to metabotropic receptor, cyclo(1-8)[Dleu(5)]OP, on GnRH mRNA expression as evaluated by in situ hybridization in castrated male rats. The administration of ODN produced a decrease in the hybridization signal while the administration of cyclo(1-8)[Dleu(5)]OP alone produced an 18% increase. When administrated concomitantly with ODN, the antagonist both inhibited the depressing effect of ODN and induced a 22% increase over the values detected in ODN-treated rats. The data suggest that the effect of ODN on GnRH mRNA expression might be mediated by interaction with metabotropic receptors.

Sex-related expression of 20alpha-hydroxysteroid dehydrogenase mRNA in the adult mouse

The enzyme 20alpha-hydroxysteroid dehydrogenase (20alpha-HSD) catalyzes the conversion of progesterone into its inactive form, 20alpha-hydroxyprogesterone. To gain information about the exact sites of 20alpha-HSD mRNA expression, we performed in situ hybridization using a (35)S-labeled cRNA probe in tissues of adult mice of both sexes. 20alpha-HSD mRNA was expressed in both male and female gonads. In the ovary, high expression was found in luteal cells of corpora lutea, while much lower expression could be detected in granulosa cells of growing follicles. In the testis, a specific hybridization signal was detected only in Leydig cells. In the female reproductive tract, 20alpha-HSD mRNA was found in the epithelial cells of the uterine cervix. In the adrenal cortex, only the zona reticularis exhibited specific radiolabeling, the expression being very high in the female and very low in the male. In the skin, specific labeling was restricted to sebaceous glands, the hybridization signal being much higher in the female than in the male. In the liver, 20alpha-HSD mRNA was found in hepatocytes, with a higher degree of expression in the female. In the kidney, specific labeling was observed in the epithelial cells of distal convoluted tubules, the signal being also much more striking in the female than in the male. In non-reproductive tissues, it clearly appears that the expression of 20alpha-HSD mRNA is higher in the female than in the male, suggesting that 20alpha-HSD may play an important role in reducing the intracellular concentration of progesterone originating from the circulation at a much higher level in the female.

KINKY POLLEN encodes a SABRE-like protein required for tip growth in Arabidopsis and conserved among eukaryotes

In higher plants, pollen tubes and root hairs share an ancient growth process named tip growth. We have isolated three allelic Arabidopsis mutant lines showing kinky-shaped pollen tubes and, when homozygous, showing shorter and thicker root hairs. The ultrastructure of pollen tubes in these kinky pollen (kip) mutants is similar to that of the wild type; however, time-lapse studies suggest that aberrant pollen tube shape is caused by periodic growth arrests alternated with phases of tube axis reorientation. The KIP gene encodes a protein of 2587 amino acids that is predicted to be targeted to the secretory pathway. KIP mRNA was detected in all organs investigated but was most abundant in pollen and roots. KIP has putative homologues in many eukaryotes, including mammals and yeast, and is similar to the Arabidopsis SABRE gene, whose mutation causes a dwarf phenotype. The phenotype of the kip/sab double mutant suggests related functions for both genes, however, the KIP protein is mostly required for tip-growth.

Lack of association between HFE gene mutations and hepatocellular carcinoma in patients with cirrhosis

BACKGROUND

Liver cirrhosis may lead to hepatocellular carcinoma (HCC), regardless of its cause. Genetic and/or environmental factors may modulate the risk of HCC. Mutations in the HFE gene are responsible for genetic haemochromatosis, a condition known to be associated with liver cirrhosis, HCC, or both. It has recently been suggested that the C282Y HFE gene mutation may be more frequent in patients with HCC that have developed in the non-cirrhotic liver than in the general population. Whether or not HFE gene mutations are associated with an increased risk of HCC in patients with cirrhosis is unknown.

AIM

To assess the prevalence of HFE gene mutations in cirrhotic patients with and without HCC.

PATIENTS AND METHODS

A total of 133 consecutive cirrhotic patients with HCC were prospectively studied for the presence of C282Y and H63D mutations. The control group consisted of 100 cirrhotic patients without HCC. We used restriction enzyme digestion of polymerase chain reaction amplified genomic DNA for determination of HFE genotypes. Iron loading was assessed on non- tumoral liver biopsy samples from 89 patients with HCC and 73 patients without HCC.

RESULTS

The prevalence of C282Y heterozygotes was similar in patients with and without HCC (5% v 4%, respectively; p=0.65) and did not differ from that expected in the general population. None of the HCC patients was found to be homozygous for C282Y or H63D, nor compound heterozygous. The prevalence of H63D heterozygotes was similar in patients with and without HCC (31% v 38%, respectively; p=0.25). No relation was detected between HFE genotypes and hepatic iron loading in patients with or without HCC.

CONCLUSION

C282Y and H63D mutations do not appear to be associated with an increased risk of HCC in patients with cirrhosis.

Inflammatory pseudotumor of the common bile duct

An exceptional cause of obstructive jaundice is reported in the present case. A 51-year-old woman progressively developed jaundice with pruritus, and abdominal ultrasonography revealed dilated intra- and extrahepatic bile ducts. Endoscopic retrograde cholangiography and endoscopic ultrasonography showed a tumor in the distal common bile duct, but failed to determine the nature of the lesion, and the patient underwent a pancreaticoduodenectomy. The final diagnosis was an inflammatory pseudotumor of the common bile duct. Inflammatory pseudotumors are uncommon, without evident pathogenesis, and are described in many organs. The localization in the common bile duct is exceptional. The prognosis is good, and a more conservative approach is possible if the diagnosis is certain before surgery.

Effect of intracerebroventricular administration of the octadecaneuropeptide on the expression of pro-opiomelanocortin, neuropeptide Y and corticotropin-releasing hormone mRNAs in rat hypothalamus

Intracerebroventricular (i.c.v.) administration of the octadecaneuropeptide (diazepam-binding inhibitor [33-50]; ODN) exerts a potent anorexigenic effect in the rat. We studied the effect of ODN on three neuropeptides involved in feeding behaviour: the orexigenic peptide neuropeptide Y (NPY) and two anorexigenic peptides, corticotropin-releasing hormone (CRH) and the pro-opiomelanocortin (POMC)-derived peptide alpha-melanocyte-stimulating hormone. The effect of i.c.v. administration of ODN (0.1 microg/kg and 1 microg/kg) on mRNA expression of the peptides in male rat hypothalamus was evaluated by semiquantitative in situ hybridization. In the arcuate nucleus, NPY-expressing neurones were mostly found in the inner zone in close proximity of the third ventricle. ODN at the dose of 0.1 microg/kg induced a significant decrease of 17.4% in NPY mRNA expression, while the depressing effect was more marked (31.4%) with the highest dose of ODN (1 microg/kg). POMC-expressing neurones were more laterally located in the arcuate nucleus. Administration of ODN at 0.1 microg/kg and 1 microg/kg doses induced increases of 33.5% and 27.4% in POMC mRNA expression, respectively. Labelling obtained with the CRH cRNA probe was essentially distributed throughout the medial parvocellular area of the hypothalamic paraventricular nucleus. ODN, at doses of 0.1 and 1 microg/kg, resulted in 17.8% and 32.8% decreases in CRH mRNA expression, respectively. The present data suggest that ODN might exert its anorexigenic effect by increasing mRNA expression of POMC and decreasing mRNA expression of NPY in the arcuate nucleus.

Role of androgens in the regulation of urotensin II precursor mRNA expression in the rat brainstem and spinal cord

It has been reported that both urotensin II precursor (pro UII) mRNA and androgen receptors (ARs) are highly expressed in rat brainstem motor nuclei and ventral horn of the spinal cord. In order to determine the possible involvement of androgens in regulation of pro UII mRNA expression, we have studied the co-localization of pro UII mRNA and AR immunoreactivity and the effect of castration and dihydrotestosterone (DHT) replacement therapy on pro UII mRNA in the rat facial nucleus and ventral horn of the spinal cord. By in situ hybridization, pro UII mRNA was only detected in motoneurons in both the facial nucleus and ventral horn of the spinal cord. Double-labelling studies revealed that the vast majority (over 95%) of motoneurons immunostained for AR also expressed pro UII mRNA in both areas examined. Three weeks after castration, pro UII mRNA expression, as measured by semi-quantitative in situ hybridization, was increased by 17% and 58% in the ventral horn of the spinal cord and the facial nucleus, respectively. The administration of DHT completely prevented the stimulating effect of castration. These results indicate that circulating androgens are exerting a down-regulation of pro UII expression possibly by a direct action at the level of motoneurons. The physiological relevance of these new findings remains to be fully explored.

Effects of estradiol on prostate epithelial cells in the castrated rat

There is evidence that estrogens can modulate the activity of prostate epithelial cells. To determine whether estradiol can have a direct influence on rat prostate, this study examined the effects of estradiol-17beta (E(2)) administered alone or in combination with dihydrotestosterone (DHT) to castrated rats for 3 weeks on prostate binding protein (PBP) C1 mRNA expression and androgen receptor (AR) localization. PBP C1 mRNA levels were measured by semi-quantitative in situ hybridization using a (35)S-labeled cDNA probe. In intact animals, strong hybridization signal could be observed in prostate sections after 12 hr of exposure to Kodak X-Omat films. In castrated rats, no PBP C1 mRNA could be detected even with longer exposure times, an effect that was prevented by administration of DHT. E(2) administered alone induced a detectable hybridization signal, and the concomitant administration of E(2) and DHT induced an increase in PBP C1 mRNA that significantly exceeded that obtained in animals that received only DHT. In prostate epithelial cells of intact animals, AR immunostaining was restricted to the nucleus. In castrated animals the alveoli were decreased in size and the epithelial cells were atrophied. AR staining was weak and was detected in both cytoplasm and nucleus. DHT administration completely obviated the effect of castration on epithelial cell histology and on AR immunostaining distribution and intensity. Interestingly, E(2) administration alone induced moderate hypertrophy of epithelial cells compared to the histological appearance of cells in untreated castrated rats. Moreover, in E(2)-treated animals the nuclear staining was much stronger than that detected in untreated castrated rats, whereas the cytoplasmic staining was not modified by the treatment. In animals that received both DHT and E(2), the staining was similar to that seen in DHT-treated rats. These results suggest that E(2) can influence the activity of rat prostate epithelial cells by mechanisms that remain to be fully clarified.

Intracrinology and the skin

The skin, the largest organ in the human body, is composed of a series of androgen-sensitive components that all express the steroidogenic enzymes required to transform dehydroepiandrosterone (DHEA) into dihydrotestosterone (DHT). In fact, in post-menopausal women, all sex steroids made in the skin are from adrenal steroid precursors, especially DHEA. Secretion of this precursor steroid by the adrenals decreases progressively from the age of 30 years to less than 50% of its maximal value at the age of 60 years. DHEA applied topically or by the oral route stimulates sebaceous gland activity, the changes observed being completely blocked in the rat by a pure antiandrogen while a pure antiestrogen has no significant effect, thus indicating a predominant or almost exclusive androgenic effect. In human skin, the enzyme that transforms DHEA into androstenedione is type 1 3beta-hydroxysteroid dehydrogenase (type 1 3beta-HSD) as revealed by RNase protection and immunocytochemistry. The conversion of androstenedione into testosterone is then catalyzed in the human skin by type 5 17beta-HSD. All the epidermal cells and cells of the sebaceous glands are labelled by type 5 17beta-HSD. This enzyme is also present at a high level in the hair follicles. Type 1 is the 5alpha-reductase isoform responsible in human skin for the conversion of testosterone into DHT. In the vagina, on the other hand, DHEA exerts mainly an estrogenic effect, this effect having been demonstrated in the rat as well as in post-menopausal women. On the other hand, in experimental animals as well as in post-menopausal women, DHEA, at physiological doses, does not affect the endometrial epithelium, thus indicating the absence of DHEA-converting enzymes in this tissue, and avoiding the need for progestins when DHEA is used as hormone replacement therapy.

FLAGdb/FST: a database of mapped flanking insertion sites (FSTs) of Arabidopsis thaliana T-DNA transformants

A large collection of T-DNA insertion transformants of Arabidopsis thaliana has been generated at the Institute of Agronomic Research, Versailles, France. The molecular characterisation of the insertion sites is currently performed by sequencing genomic regions flanking the inserted T-DNA (FST). The almost complete sequence of the nuclear genome of A.thaliana provides the framework for organising FSTs in a genome oriented database, FLAGdb/FST (http://genoplante-info.infobiogen.fr). The main scope of FLAGdb/FST is to help biologists to find the FSTs that interrupt the genes in which they are interested. FSTs are anchored to the genome sequences of A.thaliana and positions of both predicted genes and FSTs are shown graphically on sequences. Requests to locate the genomic position of a query sequence are made using BLAST programs. The response delivered by FLAGdb/FST is a graphical representation of the putative FSTs and of predicted genes in a 20 kb region.

[Epithelioid hemangioendothelioma associated with nodular regenerative hyperplasia]

Epithelioid hemangioendothelioma of the liver is a rare neoplasm of vascular origin. We report a case of epithelioid hemangioendothelioma occurring in a patient with nodular regenerative hyperplasia. This association suggests that some hepatic vascular changes might promote the growth of epithelioid hemangioendothelioma.

Effect of long-term treatment with the antiestrogen EM-652.HCl on pituitary estrogen receptor alpha and prolactin mRNA expression in intact, ovariectomized and gonadotropin-releasing hormone-treated female rats

Estrogen receptor alpha (ERalpha) is the predominant estrogen receptor subtype in the anterior pituitary gland. In order to assess the influence of the pure antiestrogen EM-652.HCl on ERalpha gene transcription, we have studied the effect of long-term administration of the antiestrogen in ovariectomized rats as well as in intact female rats treated or not with the GnRH-agonist D-trp(6), des-Gly-NH2(10) GnRH ethylamide (GnRH-A), a treatment which induces pharmacological castration. To evaluate the degree of pituitary responsiveness to changes in estrogen exposure, prolactin (PRL) mRNA levels were also measured. ERalpha and PRL mRNA levels were evaluated by quantitative in situ hybridization. It was found that, 49 weeks after ovariectomy (OVX), pituitary ERalpha mRNA levels were decreased by 55%. Long-term administration (49 weeks) of EM-652.HCl to OVX animals resulted in a further 41% decrease in ERalpha mRNA. On the other hand, ovariectomy induced an 82% decrease in PRL mRNA levels while the administration of EM-652.HCl to OVX animals did not further decrease PRL mRNA. The administration of EM.652.HCl or GnRH-A alone to intact rats during 52 weeks did not significantly modify pituitary ERalpha mRNA levels. Concomitant administration of both GnRH-A and EM-652.HCl induced 41 and 47% decreases in ERalpha mRNA levels, when compared to the levels measured in vehicle-treated and GnRH-treated animals respectively. Combined administration of EM.652.HCl and GnRH-A induced 56 and 65% decreases in PRL mRNA, respectively. When EM-652.HCl was administered concomitantly with GnRH-A, the inhibitory effect on PRL mRNA levels was more marked than that observed in GnRH-A-treated animals. The present data demonstrate that when circulating estrogens are absent or maintained at very low levels by GnRH administration, EM-652.HCl can still depress ERalpha gene transcription. It is suggested that estrogens can positively regulate pituitary ERalpha gene transcription and that the antiestrogen EM-652.HCl can downregulate by itself pituitary ERalpha gene transcription.