Expression and functionality of luteinizing hormone/chorionic gonadotropin receptor in the rat prostate

Time of day modified the time required for semen collection with electroejaculation and slightly affected the quality of fresh semen in rams

The aim was to compare some stress responses to electroejaculation (EE), and the quality of fresh semen, when ram semen is collected at dawn (06:00 h), noon (12:00 h), or evening (18:00 h). Twelve Corriedale rams were used, and semen was collected from four rams at each study time on three different days, with a Latin-square design. The time required for EE, the number of vocalizations emitted, heart rate, and rectal temperature were recorded, and fresh semen was evaluated. The time required for EE was shorter at evening than at dawn and noon (399.3 s, 480.6 s, and 460.2 s respectively; pooled SEM = 72.1; P = 0.03). The percentage of sperm with progressive motility was greater at noon than dawn (59.7% and 50.3%; pooled SEM = 5.8; P = 0.05). Curvilinear velocity was greater at dawn than evening (117.0 µm/s and 95.5 µm/s; pooled SEM = 7.1; P = 0.04), slow linear velocity was greater at evening than at dawn and noon (13.1 µm/s, 9.3 µm/s, and 8.5 µm/s respectively; pooled SEM = 1.7, P = 0.05), and the slow average path velocity was greater at evening than dawn and noon (16.2 µm/s, 11.7 µm/s, and 10.8 µm/s respectively; pooled SEM = 1.9, P = 0.05). In conclusion, the collection time modified the time required for electroejaculation and had only slight effects on the quality of fresh semen. Overall, the time of the day appears to have only slight effects on semen collection and quality.

Possible Relationship between Long-Term Adverse Health Effects of Gonad-Removing Surgical Sterilization and Luteinizing Hormone in Dogs

Spaying and neutering dogs is commonly used to prevent the birth of unwanted animals and eliminate the risk of reproductive diseases. However, removal of the gonads prevents the feedback of estrogen and testosterone on the pituitary and hypothalamus. As a result, luteinizing hormone (LH) is continuously elevated at supraphysiologic concentrations. Although the main role of LH is for reproductive function (e.g., ovulation), there are LH receptors present in several normal tissues including the thyroid and adrenal glands, gastrointestinal tract, cranial cruciate ligament and round ligament, and lymphocytes. In addition, there are LH receptors present in several neoplastic tissues (e.g., lymphoma, hemangiosarcoma, mastocytoma, transitional cell carcinoma, and osteosarcoma). The role of LH receptors in non-reproductive normal and neoplastic tissues is not known but may stimulate nitric oxide release and induce cell division. The precise etiology of the increased incidence of several non-reproductive long-term health complications following spaying and neutering is not known but may be related to LH receptor activation in these non-reproductive target tissues. How these effects may be mediated is described in this review.

Regulation of prostate cancer by hormone-responsive G protein-coupled receptors

Regulation of prostate cancer by androgen and androgen receptor (AR), and blockade of AR signaling by AR antagonists and steroidogenic enzyme inhibitors have been extensively studied. G protein-coupled receptors (GPCRs) are a family of membrane receptors that regulate almost all physiological processes. Nearly 40% of FDA-approved drugs in the market target GPCRs. A variety of GPCRs that mediate reproductive function have been demonstrated to be involved in the regulation of prostate cancer. These GPCRs include gonadotropin-releasing hormone receptor, luteinizing hormone receptor, follicle-stimulating hormone receptor, relaxin receptor, ghrelin receptor, and kisspeptin receptor. We highlight here GPCR regulation of prostate cancer by these GPCRs. Further therapeutic approaches targeting these GPCRs for the treatment of prostate cancer are summarized.

Effects of luteinizing hormone receptor signaling in prostate cancer cells

BACKGROUND

The importance of androgen signaling in prostate cancer (PC) is well described and prostate cancer cells retain the ability to directly synthesize androgens. Luteinizing hormone (LH) can induce expression of steroidogenic enzymes and trigger androgen production, but the regulation of this process is not well-described. Here, we explored the impact of silencing LH receptor (LHR) silencing on androgen synthesis and on several relevant signaling pathways in PC.

METHODS

LHR mRNA and protein expression was evaluated in LNCaP PC cells treated with LHR-siRNA. MTS assay was used to measure the effect of LHR-siRNA on proliferation in LNCaP and 22RV1 PC cells. Treated LNCaP and LAPC-3 cells were also assayed for differences in androgen synthesis and expression of steroidogenic enzymes, PSA, AR, and critical signaling molecules including PKA, ERK1/2, PI3K, AKT2, and HER2.

RESULTS

We confirmed that functional LHR is expressed in both androgen-sensitive and castrate-resistant PC specimens. Treatment with LHR-siRNA effectively silenced LHR gene and protein expression and prevented LH-mediated proliferation and androgen synthesis in prostate cancer cells. LHR silencing also downregulated expression of AR, PSA, PKA, ERK1/2, PI3K, AKT2, and HER2.

CONCLUSION

Collectively, these data demonstrate that silencing LHR expression suppresses androgen synthesis and signaling and the LH-LHR pathway may represent a viable therapeutic strategy in PC.

Differential action of glycoprotein hormones: significance in cancer progression

Growth of multicellular organisms depends on maintenance of proper balance between proliferation and differentiation. Any disturbance in this balance in animal cells can lead to cancer. Experimental evidence is provided to conclude with special reference to the action of follicle-stimulating hormone (FSH) on Sertoli cells, and luteinizing hormone (LH) on Leydig cells that these hormones exert a differential action on their target cells, i.e., stimulate proliferation when the cells are in an undifferentiated state which is the situation with cancer cells and promote only functional parameters when the cell are fully differentiated. Hormones and growth factors play a key role in cell proliferation, differentiation, and apoptosis. There is a growing body of evidence that various tumors express some hormones at high levels as well as their cognate receptors indicating the possibility of a role in progression of cancer. Hormones such as LH, FSH, and thyroid-stimulating hormone have been reported to stimulate cell proliferation and act as tumor promoter in a variety of hormone-dependent cancers including gonads, lung, thyroid, uterus, breast, prostate, etc. This review summarizes evidence to conclude that these hormones are produced by some cancer tissues to promote their own growth. Also an attempt is made to explain the significance of the differential action of hormones in progression of cancer with special reference to prostate cancer.

The potentiality of medicinal plants as the source of new contraceptive principles in males

Rising human population throughout the world especially in developing and underdeveloped countries has detrimental effects on life supporting system on earth. Traditionally, plants have been used to treat different kinds of ailments. The growing importance of phytochemicals in males has been reported. Contraceptive ability of plants has been reported in several animal models. The reversibility of the anti-fertility effects of plants and its active compounds are of potential clinical relevance in the development of male contraceptive. This review attempts to discuss the latest reports on the potentiality of medicinal plants as the source of new contraceptive principles in males.

LH receptor gene expression in cumulus cells in women entering an ART program

PURPOSE

Luteinizing hormone (LH) exerts its actions through its receptor (LHR), which is mainly expressed in theca cells and to a lesser extent in oocytes, granulosa and cumulus cells. The aim of the present study was the investigation of a possible correlation between LHR gene and LHR splice variants expression in cumulus cells and ovarian response as well as ART outcome.

METHODS

Forty patients undergoing ICSI treatment for male factor infertility underwent a long luteal GnRH-agonist downregulation protocol with a fixed 5-day rLH pre-treatment prior to rFSH stimulation and samples of cumulus cells were collected on the day of egg collection. RNA extraction and cDNA preparation was followed by LHR gene expression investigation through real-time PCR. Furthermore, cumulus cells were investigated for the detection of LHR splice variants using reverse transcription PCR.

RESULTS

Concerning LHR expression in cumulus cells, a statistically significant negative association was observed with the duration of ovarian stimulation (odds ratio = 0.23, p = 0.012). Interestingly, 6 over 7 women who fell pregnant expressed at least two specific types of LHR splice variants (735 bp, 621 bp), while only 1 out of 19 women that did not express any splice variant achieved a pregnancy.

CONCLUSIONS

Consequently, the present study provide a step towards a new role of LHR gene expression profiling as a biomarker in the prediction of ovarian response at least in terms of duration of stimulation and also a tentative role of LHR splice variants expression in the prediction of pregnancy success.

Phytochemical evaluation and antispermatogenic activity of Thevetia peruviana methanol extract in male albino rats

This study was conducted to evaluate the antifertility potential of Thevetia peruviana (Apocynaceae) in male albino rats with their phytochemical evaluations. Phytochemical examination showed that plant is rich in active constituents, i.e. α-amyrin acetate, lupeol acetate, α-amyrin, β-amyrin, lupeol and thevetigenin. T. peruviana stem bark methanol extract (TPMtE) administered orally to male rats at the dose level of 100 mg/rat/day did not cause any significant reduction in body weight, while the weight of reproductive organs reduced significantly. A significant fall in the total protein and sialic acid content of the testes, epididymides, seminal vesicle and ventral prostate, as well as in the glycogen content of testes was also observed; however, cholesterol was increased significantly. TPMtE also caused a decline in spermatogenic elements, i.e. preleptotene and pachytene spermatocytes, secondary spermatocytes, round spermatids and mature Leydig cells. At this dose level Leydig cell nuclear diameter, seminiferous tubular diameter and Sertoli area were significantly reduced (p < 0.001). The reduction in sperm density and motility resulted in 18% residual fertility. In conclusion, T. peruviana inhibited spermatogenesis in rats, indicating the possibility of developing a herbal male contraceptive.

Effects of Cynodon dactylon on Stress-Induced Infertility in Male Rats

Cynodon dactylon (Family: Poaceae) is known to be a tackler in Indian mythology and is offered to Lord Ganesha. It is found everywhere, even on waste land, road side, dry places, and spreads vigorously on cultivated ground. This study was carried out with an objective to test if the constituents of this plant are useful in coping stress-induced sexual In this study, we considered immobilization stress to induce male infertility and the effect of C. dactylon in restoration of the dysfunction was evaluated by considering sexual behavioral observations, sexual performance, fructose content of the seminal vesicles, epididymal sperm concentration and histopathological examinations as parameters. Treatment of rats under stress with methanolic extract of C. dactylon has shown a promising effect in overcoming stress-induced sexual dysfunction, sexual performance, fructose content, sperm concentration and its effect on accessory sexual organs and body weight. We conclude that active constituents of C. dactylon present in methanolic extract have a potent aphrodisiac and male fertility activity.

Evaluation of reversible contraceptive activities of Cuminum cyminum in male albino rats

BACKGROUND

The aim of the present study was to evaluate the contraceptive efficacy of Cuminum cyminum (jeera) seeds in male albino rats.

STUDY DESIGN

C. cyminum methanol extract (CcMtE) at dose levels of 100 and 200 mg/rat/day was orally administered to male rats for 60 days. The effect of the treatment on reproductive organs and fertility was investigated. Recovery and toxicity studies were also carried out.

RESULTS

C. cyminum methanol extract fed to male rats for 60 days did not cause any alterations in the body weight, whereas the weight of testes, epididymides, seminal vesicles and ventral prostate were significantly reduced (p≤.001). Animals treated with CcMtE showed a marked reduction in sperm density in the cauda epididymis and testes and sperm motility in the cauda epididymis. Reduction in fertility was 69.0% and 76.0% in 100 and 200 mg/rat/day dose levels, respectively. The circulatory hormones were also reduced significantly. Testicular biochemical analysis of protein, sialic acid, glycogen, ascorbic acid and fructose indicated a marked decline, whereas testicular cholesterol content was significantly increased, which showed altered biochemistry of the reproductive organs. After CcMtE treatment, significant decreases (p≤.001) were observed in the number of testicular cells (i.e., spermatogonia, primary spermatocytes [preleptotene and pachytene], secondary spermatocytes and round spermatids); nonsignificant change was observed in the Sertoli cell count. The treatment had no effect on levels of serum protein, cholesterol, bilirubin, glutamic oxaloacetic transaminase (GOT), glutamic pyruvic transaminase (GPT), blood urea and hematological indices.

CONCLUSIONS

The present study shows that C. cyminum treatment resulted in the inhibition of spermatogenesis and fertility without producing apparent toxic effects.

Participation of signaling pathways in the derepression of luteinizing hormone receptor transcription

The luteinizing hormone receptor (LHR) transcription is subject to an epigenetic regulatory mode whereby the proximal Sp1 site acts as an anchor to recruit histone deacetylases (HDAC)1/2 and the Sin3A co-repressor complex. This results in promoter-localized histone hypo-acetylation that contributes to the silencing of LHR transcriptional expression. Chromatin changes resulting from site-specific acetylation and methylation of histones regulate LHR gene expression. The HDAC inhibitor TSA-induced cell-specific phosphatase release from the promoter, which serves as an 'on' mechanism for Sp1 phosphorylation by phosphatidylinositol 3-kinase/protein kinase Czeta (PI3K/PKCzeta) at Ser641, leading to p107 repressor derecruitment and LHR transcriptional activation. The methylation status of the promoter provides another layer of modulation in a cell-specific manner. Maximal derepression of the LHR gene is dependent on complete DNA demethylation of the promoter in conjunction with histone hyperacetylation and release of repressors (p107 and HDAC/Sin3A). Independently, the PKC-alpha/Erk pathway, participates in LHR gene expression through induction of Sp1 phosphorylation at Ser site(s) other than Ser641. This causes dissociation of the HDAC1/mSin3A from the promoter, recruitment of TFIIB and Pol II, and transcriptional activation. Collectively, these findings demonstrate that LHR gene expression at the transcriptional level is regulated by complex and diverse networks, in which coordination and interactions between these regulatory effectors are crucial for silencing/activation of LHR expression.

Male gonadal function, prolactin secretion and lactotroph population in an experimental model of cirrhosis

Liver cirrhosis, a highly prevalent chronic disease, is frequently associated with endocrine dysfunctions, notably in the gonadal axis. We evaluated lactotroph population by immunohistochemistry, gonadotropins and prolactin by immunoradiometric assay and testosterone and estradiol by radioimmunoassay in adult male Wistar rats with cirrhosis induced by carbon tetrachloride. No significant difference in mean +/- SEM percentages of lactotrophs was found between cirrhotic animals and controls (N = 12, mean 18.95 +/- 1.29%). Although there was no significant difference between groups in mean serum levels of prolactin (control: 19.2 +/- 4 ng/mL), luteinizing hormone (control: 1.58 +/- 0.43 ng/mL), follicle-stimulating hormone (control: 19.11 +/- 2.28 ng/mL), estradiol (control: 14.65 +/- 3.22 pg/mL), and total testosterone (control: 138.41 +/- 20.07 ng/dL), 5 of the cirrhotic animals presented a hormonal profile consistent with hypogonadism, all of them pointing to a central origin of this dysfunction. Four of these animals presented high levels of estradiol and/or prolactin, with a significant correlation between these two hormones in both groups (r = 0.54; P = 0.013). It was possible to detect the presence of central hypogonadism in this model of cirrhotic animals. The hyperestrogenemia and hyperprolactinemia found in some hypogonadal animals suggest a role in the genesis of hypogonadism, and in the present study they were not associated with lactotroph hyperplasia.

Expression of the mature luteinizing hormone receptor in rodent urogenital and adrenal tissues is developmentally regulated at a posttranslational level

The LH receptor (LHR) is a G protein-coupled receptor involved in the regulation of ovarian and testicular functions. In this study we demonstrate novel and unexpected patterns of receptor expression and regulation in fetal and adult rodent urogenital and adrenal tissues. Two rat LHR promoter fragments (approximately 2 and 4 kb) were shown to direct expression of the lacZ reporter in transgenic mice to gonads, adrenal glands, and kidneys, starting at 14.5 d post coitum, and to genital tubercles, starting at 11.5 d post coitum. These tissues were also found to express the full-length LHR mRNA and protein during rat fetal development, but, importantly, only immature receptors carrying unprocessed N-linked glycans were detected. After birth, the receptor gene activity ceased, except in the gonads, which started to express the mature receptor carrying fully processed N-linked glycans. Surprisingly, both LHR mRNA and mature protein levels were up-regulated substantially in pregnant female adrenal glands and kidneys at a time that coincides with differentiation of fetal urogenital tissues. Taken together, these results indicate that the LHR protein is expressed constitutively in gonadal and nongonadal urogenital tissues as well in adrenal glands, but its final functional maturation at the posttranslational level appears to be developmentally and physiologically regulated.

Effect of Saponins of Albizia lebbeck (L.) Benth bark on the reproductive system of male albino rats

Oral administration of saponins isolated from Albizia lebbeck bark at the dose level of 50 mg/kg/b.w. per day for 60 days to male rats brought about a significant decrease in the weights of testes, epididymides, seminal vesicle and ventral prostate. The production of round spermatid was reduced by 73.04% in Albizia lebbeck treated rats. The population of preleptotene spermatocytes and spermatogonia were reduced by 65.07% and 47.48% and secondary spermatocytes by 73.41%, respectively. Cross sectional surface area of Sertoli cells as well as the cell counts were found to be depleted significantly. Leydig cell nuclear area and number of mature Leydig cells were decreased by 57.47% and 54.42%, respectively. Sperm motility as well as sperm density were reduced significantly. Albizia lebbeck reduced the fertility of male rats by 100%. There were no significant changes in RBC and WBC count, haemoglobin, haematocrit and glucose in the blood and cholesterol, protein, triglyceride and phospholipid in the serum. The protein, glycogen and cholesterol contents of the testes, fructose in the seminal vesicle and protein in epididymides were significantly decreased. Histoarchitecture of the testes showed vacuolization at primary spermatocytes stage. Highly reduced seminiferous tubular diameter and increased intertubular space were also observed when compared to controls.

The follicle-deplete mouse ovary produces androgen

The follicle-depleted postmenopausal ovary is enriched in interstitial cells that produce androgens. This study was designed to cause follicle depletion in mice using the industrial chemical, 4-vinylcyclohexene diepoxide (VCD), and characterize the steroidogenic capacity of cells in the residual ovarian tissue. From a dose-finding study, the optimal daily concentration of VCD was determined to be 160 mg/kg. Female B6C3F(1) immature mice were treated daily with vehicle control or VCD (160 mg kg(-1) day(-1), 15 days, i.p.). Ovaries were removed and processed for histological evaluation. On Day 15 following onset of treatment, primordial follicles were depleted and primary follicles were reduced to about 10% of controls. On Day 46, primary follicles were depleted and secondary and antral follicles were reduced to 0.7% and 2.6% of control, respectively. Seventy-five percent of treated mice displayed disruptions in estrous cyclicity. All treated mice were in persistent diestrus (acyclic) by Day 58. Plasma FSH levels were increased (P < 0.05) relative to controls on Day 37 and had plateaued by Day 100. Relative to age-matched cyclic controls, by Day 127, the significant differences in VCD-treated mice included reduced ovarian and uterine weights, elevated plasma LH and FSH, and reduced plasma progesterone and androstenedione. Furthermore, plasma 17beta-estradiol levels were nondetectable. Unlike controls, immunostaining for LH receptor, and the high density lipoprotein receptor (SR-BI), was diffuse in ovarian sections from VCD-treated animals. Ovaries from Day 120 control and VCD-treated animals were dissociated and dispersed cells were placed in culture. Cultured cells from ovaries of VCD-treated animals produced less LH-stimulated progesterone than control cells. Androstenedione production was nondetectable in cells from cyclic control animals. Conversely, cells from VCD-treated animals produced androstenedione that was doubled in the presence of insulin and LH (1 and 3 ng/ml). Collectively, these data demonstrate that VCD-mediated follicle depletion results in residual ovarian tissue that may be analogous to the follicle-deplete postmenopausal ovary. This may serve as a useful animal model to examine the dynamics of follicle loss in women as ovarian senescence ensues.

Elevated steroidogenesis, defective reproductive organs, and infertility in transgenic male mice overexpressing human chorionic gonadotropin

We previously developed a transgenic (TG) mouse model that overexpresses the human chorionic gonadotropin (hCG) beta-subunit under the universal human ubiquitin C promoter, displaying in males a modest 3-fold increase in circulating levels of LH/hCG bioactivity. The males were fertile and presented with a mild reproductive phenotype. To achieve higher levels of hCG, a double TG model was generated by cross-breeding the hCG beta-expressing mice with another TG line harboring a ubiquitin C/common alpha-subunit fusion gene. The double-TG mice expressed excessive levels of dimeric hCG, with 2000-fold elevated circulating LH/hCG bioactivity. These male mice were infertile, primarily due to inability to copulate, and they showed enhanced testicular androgen production despite clear down-regulation of LH/hCG receptors. Their intratesticular inhibin B was unaltered, but serum FSH was markedly reduced. Apparently the chronic hCG hyperstimulation led to focal Leydig cell proliferation/hypertrophy at 6 months of age, but failed to promote testicular tumors. Even though full spermatogenesis occurred in most of the seminiferous tubules, progressive tubule degeneration was apparent as the males grew older. The prostate and seminal vesicles were enlarged by distension of glandular lumina. Functional urethral obstruction was indicated by distension and sperm accumulation in distal vas deferens as well as by dilated urinary bladder and enlarged kidneys. The abnormal function of accessory sex glands and/or lower urinary tract as a consequence of the disturbed sex hormone balance or direct action of hCG may be the main cause of infertility in this model. The present study provides in vivo evidence that exposure of male mice to chronically elevated levels of hCG severely affects their urogenital tract function at multiple sites and causes infertility, but, unlike in LH/hCG overexpressing female mice, it is not tumorigenic.

Partial characterization of chorionic gonadotropin-like binding sites from the bacteria Xanthomonas maltophilia

The gram-negative bacterium, Xanthomonas maltophilia, has low- and high-affinity luteinizing hormone/chorionic gonadotropin (LH/CG)-binding sites, similar to the LH/CG receptor found in mammals. Although the low-affinity site binds both LH and human CG (hCG), the high-affinity site is specific for hCG. In the current investigation, these two binding sites were independently isolated from X. maltophilia for further characterization. To isolate functional binding sites, we developed a solubilization method using the detergent zwittergent 3,14 and high glycerol concentrations that allowed for the maintenance of ligand-binding integrity. Gel filtration experiments established molecular weights of 170 and 11.5 kDa for the two binding sites, which were supported by data from photoaffinity labeling and ultracentrifugation experiments. Gel filtration data also suggested the presence of a third binding site of 5.4 kDa. The 170-kDa site had a binding affinity of Kd = 12 x 10(-6) and bound both LH and hCG. The small molecular weight site had an affinity of Kd = 9.4 x 10(-8) and was CG specific. Collectively, these data demonstrate the presence of multiple hormone binding sites in X. maltophilia that differ in molecular size, binding affinity, and ligand specificity.

Multiple luteinizing hormone receptor (LHR) protein variants, interspecies reactivity of anti-LHR mAb clone 3B5, subcellular localization of LHR in human placenta, pelvic floor and brain, and possible role for LHR in the development of abnormal pregnancy, pelvic floor disorders and Alzheimer's disease

Distinct luteinizing hormone receptor (LHR) protein variants exist due to the posttranslational modifications. Besides ovaries, LHR immunoreactivity (LHRI) was also found in other tissues, such as the brain, fallopian tube, endometrium, trophoblast and resident tissue macrophages. The 3B5 mouse monoclonal antibody was raised against purified rat LHR. In rat, porcine and human ovaries, the 3B5 identified six distinct LHR bands migrating at approximately 92, 80, 68, 59, 52 and 48 kDa. Characteristic LHRI was detected in rat, human and porcine corpora lutea. During cellular differentiation, subcellular LHR distribution changed from none to granular cytoplasmic, perinuclear, surface, nuclear and no staining. There were also differences in vascular LHR expression--lack of LHRI in ovarian vessels and strong staining of vessels in other tissues investigated. In normal human term placentae, villous LHRI was associated with blood sinusoids and cytotrophoblast cells, and rarely detected in trophoblastic syncytium. In all abnormal placentae, the LHRI of sinusoids was absent, and syncytium showed either enhanced (immature placental phenotypes) or no LHRI (aged placental phenotype). LHRI in human brain was identified in microglial cells (CD68+ resident macrophages). Protein extracts from human vaginal wall and levator ani muscle and fascia showed strong approximately 92 and 68 kDa species, and LHRI was detected in smooth muscle cells, fibroblasts, resident macrophages and nuclei of skeletal muscle fibers. Our observations indicate that, in contrast to the theory on the role of vascular hormone receptors in preferential pick up of circulating hormones, there is no need to enhance selective pick up rather only prevent LH/CG transport to inappropriate sites. Abnormal placental LHR expression may play a role in the development of abnormal pregnancy. Expression of LHR in the pelvic floor compartments suggests that high LH levels in postmenopausal women may contribute to the pelvic floor relaxation and increased incidence of pelvic floor disorders. Since chorionic gonadotropin increases secretion of a variety of cytokines by monocytes, and induces their inflammatory reaction and phagocytic activity, high LH levels in aging individuals may also activate microglia (mononuclear phagocyte system in the central nervous system) and contribute to the development of Alzheimer's disease and other inflammation-mediated neurodegenerative diseases.

Epididymal phenotype in luteinizing hormone receptor knockout animals and its response to testosterone replacement therapy

Previous studies reported that epididymis contains functional LH receptors. The LH receptor knockout mice, which have epididymal phenotypes, gave us an opportunity to test the hypothesis that testosterone replacement alone may not be sufficient to reverse phenotypes to wild-type epididymis. The morphological phenotype in knockout animals includes a decrease in luminal diameter of the proximal and distal caput and cauda epididymis, the absence of clear and halo cells in the epithelial lining, a decrease in the height of principal cells and the number of cells containing cilia, a decrease in cilia length, and a change from basal to central location of nuclei in the principal cells. The biochemical phenotype includes a decrease in periodic acid-Schiff reaction product, reflecting the glycogen and glycoprotein synthesis and secretion, a decrease in androgen receptor (AR) and estrogen receptor (ER)beta, and an increase in ERalpha levels. Twenty-one-day testosterone replacement therapy in 30-day-old knockout animals reversed some, but not all, morphological and biochemical phenotypes. Those that did not reverse include luminal diameters of proximal and distal caput and cauda epididymis, the percentage of ciliated principal cells in caput epididymis, and nuclear AR localization. In summary, while our results reaffirm that androgens are important for normal epididymal morphology and function, they indicate that LH could be required for certain facets of epididymal morphology and/or function.

Transgenic mice harboring murine luteinizing hormone receptor promoter/beta-galactosidase fusion genes: different structural and hormonal requirements of expression in the testis, ovary, and adrenal gland

In vivo regulation of the LH receptor (LHR) promoter was studied using transgenic (TG) mice harboring fusion genes containing three different lengths of the LHR promoter (7.4 kb, 2.1 kb, and 173 bp), fused with coding sequence of the Escherichia coli beta-galactosidase (beta-GAL) reporter gene. The length of the LHR promoter significantly affected the pattern of beta-GAL expression. In the testis the shortest promoter directed expression primarily of the full-length beta-GAL mRNA, but mainly truncated messages were transcribed from the longer LHR promoter/beta-GAL constructs. The case was reversed in the ovary and adrenal gland. Furthermore, we have recently detected strong LHR expression in the adrenal gland of female mice with chronically elevated serum LH. Therefore, the regulation of the adrenal LHR expression was addressed in the present study using the LHR/beta-GAL TG mice. Elevated LH levels were achieved in the LHR/beta-GAL mice either by gonadectomy or cross-breeding them with TG mice overexpressing a chimeric protein of bovine LH beta-subunit and the C-terminal fragment of human chorionic gonadotropin-beta. In both models, beta-GAL mRNA was found in the adrenal cortex when the 7.4-kb LHR promoter was applied but not in mice carrying the 173-bp LHR promoter. The 7.4-kb construct was activated also in the ovaries in the double TG LHR(beta-GAL)/bovine LH beta-subunit/C-terminal fragment of human chorionic gonadotropin-betamice in some theca-interstitial cells surrounding the follicles. Hence, the LHR promoter elements essential for directing beta-GAL expression to the adrenal gland and ovary (7.4 kb) are different from those recently shown to be essential for the testicular expression (173 bp). In conclusion, elevated serum LH concentrations were found seminal for the LHR promoter activation in the ovaries and adrenals, and different lengths of the promoter are responsible for reporter gene expression in the testis, ovary, and adrenal gland.

Targeted destruction of androgen-sensitive and -insensitive prostate cancer cells and xenografts through luteinizing hormone receptors

BACKGROUND

We have prepared a conjugate of a lytic peptide (hecate) and a 15-amino acid segment of the beta-chain of LH to test the concept that this conjugate will target cancer cells expressing LH receptors.

METHODS

Hecate-betaLH was added in vitro to cultures of Chinese hamster ovary (CHO) cells with and without LH receptors and to prostate cancer cells in the presence or absence of steroids, follicle-stimulating hormone (FSH), epidermal growth factor (EGF), or betaLH. PC-3 xenografts were established in male athymic nude mice and treated once a week for 3 weeks with hecate-betaLH via the lateral tail vein.

RESULTS

The conjugate showed concentration-dependent toxicity for the following prostate cancer cell lines: BRF 41 T>DU145>PC-3>LNCaP, according to their LH receptor capacities. Steroid removal reduced sensitivity to the drug in a reversible manner. Hecate-betaLH reduced the tumor burden in the nude mice from 60 to 12.5 mg/g body weight.

CONCLUSIONS

We conclude that the hecate-betaLH conjugate selectively kills androgen-dependent and-independent prostate cancer cells both in vivo and in vitro; its toxicity depends on the number of LH receptor sites present.

Mutations of gonadotropins and gonadotropin receptors: elucidating the physiology and pathophysiology of pituitary-gonadal function

The recent unraveling of structures of genes for the gonadotropin subunits and gonadotropin receptors has provided reproductive endocrinologists with new tools to study normal and pathological functions of the hypothalamic-pituitary-gonadal axis. Rare inactivating mutations that produce distinctive phenotypes of isolated LH or FSH deficiency have been discovered in gonadotropin subunit genes. In addition, there is a common polymorphism in the LHbeta subunit gene with possible clinical significance as a contributing factor to pathologies of LH-dependent gonadal functions. Both activating and inactivating mutations have been detected in the gonadotropin receptor genes, a larger number in the LH receptor gene, but so far only a few in the gene for the FSH receptor. These mutations corroborate and extend our knowledge of clinical consequences of gonadotropin resistance and inappropriate gonadotropin action. The information obtained from human mutations has been complemented by animal models with disrupted or inappropriately activated gonadotropin ligand or receptor genes. These clinical and experimental genetic disease models form a powerful tool for exploring the physiology and pathophysiology of gonadotropin function and provide an excellent example of the power of molecular biological approaches in the study of pathogenesis of diseases.

Age- and sex-specific promoter function of a 2-kilobase 5'-flanking sequence of the murine luteinizing hormone receptor gene in transgenic mice

A transgenic (TG) mouse model carrying a 2-kb murine LH receptor (LHR) promoter/beta-galactosidase (beta-GAL) fusion gene was created to study the regulatory function of the 5'-flanking region of the murine LHR gene. Of the five TG mouse lines produced, three displayed high beta-GAL expression in the testis, but none showed any expression in the ovary. In addition, all mouse lines of both sexes expressed beta-GAL consistently in the brain, most prominently in hippocampus, hypothalamus, midbrain, and cortex. Weak staining was found in a few pituitary samples. All other tissues examined were negative for transgene expression. In support of sex-specific gonadal expression of the transgene, transient transfection of the LHR/beta-GAL gene construct into immortalized mouse granulosa (KK-1) and Leydig (mLTC-1) tumor cells revealed a more than 5-fold higher expression level in the Leydig cells. Histological examination of the TG testes demonstrated strong beta-GAL expression in Leydig cells, but, unexpectedly, also in elongating spermatids of adult age and in some spermatogonia of the neonatal testis. The functional significance of the latter findings remains open. The transgene was only expressed in adult Leydig cells; no expression was found in the fetal population of these cells. Hence, these findings indicate that the immediate 2-kb fragment of the murine LHR 5'-flanking sequence is transcriptionally active only in adult Leydig cells and certain brain areas, but other promoter sequences are apparently needed for ovarian and fetal testicular expression of the LHR gene.

Effects of pituitary hormones on the prostate

BACKGROUND

Although essential, androgens alone are not sufficient to induce normal growth and functionality of the prostate. Nonandrogenic hormones must also be involved in the proliferation of the prostate cancer cells which do not respond to antiandrogenic therapy and which thus become androgen-independent. Prolactin, but also growth hormone and luteinizing hormone, are potentially able to act on both normal and abnormal prostatic cells.

METHODS

In this review we summarize data from the literature concerning the physiological and pathological implications of prolactin, growth hormone, and luteinizing hormone on the prostate.

RESULTS

In rodent prostates, prolactin and growth hormone can induce a variety of effects independently of androgens (e.g., transactivation of certain genes, or synthesis of the major secretion products). Moreover, hyperprolactinemia is responsible for inflammation and dysplasia of the gland, while growth hormone promotes the development of prostate tumors in vivo in the mouse and rat. Growth hormone acts on the gland directly, through prostatic growth hormone receptors, and/or indirectly via the stimulation of insulin-like growth factor-I (IGF-I) synthesis in the liver. Luteinizing hormone receptor is expressed in rat and human prostates. Luteinizing hormone increases the amount of various transcripts in the rat prostate through an androgen-independent pathway.

CONCLUSIONS

Prolactin, growth hormone, and luteinizing hormone, alone or synergistically with androgens, play physiologically significant roles in the normal prostate. The involvement of these hormones in the development of benign prostatic hyperplasia and prostatic carcinoma is an issue that needs to be addressed.

Coexpression of gonadotropic hormones and their corresponding FSH- and LH/CG-receptors in the human prostate

BACKGROUND

Benign prostatic hyperplasia (BPH) affects the majority of elderly men, and prostate cancer is the most common male cancer. Prostatic growth and function are thought to be regulated by steroid hormones, primarily androgens and estrogens, but nonandrogenic hormones must also be considered. The increasing evidence of para/autocrine functions of the gonadotropic glycoprotein-hormones (GPH), their allocation to the superfamily of cystine-knot growth factors, and luteinizing hormone (LH)/chorionic gonadotropin (CG)-receptor (R) gene expression in nongonadal tissues led us to investigate intraprostatic GPH and GPH-R gene expression.

METHODS AND RESULTS

RT-PCR and subsequent Southern hybridization and/or restriction enzyme analysis of BPH and prostatic adenocarcinoma demonstrated that all three human (h) gonadotropic hormones, i.e., follicle-stimulating hormone (FSH), LH, and CG, as well as the corresponding FSH-R and LH/CG-R, are transcribed intraprostatically. Significant amounts of the alpha and beta subunits of hCG were secreted by short-term primary cultures of human BPH tissues, as detected by highly sensitive and specific time-resolved immunofluorometric assays (IFMAs).

CONCLUSIONS

Our data suggest that prostatic- and pituitary-derived GPH act directly on the prostatic gland, particularly FSH via the FSH-R, thereby possibly modulating locally acting key hormones and growth factors involved in BPH development.

The luteinizing hormone receptor

The luteinizing hormone receptor (LHR) is a member of the subfamily of glycoprotein hormone receptors within the superfamily of G protein-coupled receptor (GPCR)/seven-transmembrane domain receptors. Over the past eight years, major advances have been made in determining the structure and function of the LHR and its gene. The hormone-binding domain has been localized to exons 1-7 in the extracellular (EC) domain/region of the receptor, which contains several leucine-rich repeats. High-affinity binding of LH and human chorionic gonadotrophin (hCG) causes secondary hormone or receptor contacts to be established with regions of the EC loop/transmembrane module that initiate signal transduction. Models of hormone-receptor interaction have been derived from the crystal structures of hCG and of the ribonuclease inhibitor, which also contains leucine-rich repeats. Such models provide a framework for the interpretation of mutational studies and for further experiments. The extracellular domain of the receptor has been overexpressed in vitro, which will facilitate crystallographic resolution of the structure of the receptor-binding site. The transmembrane domain/loop/cytoplasmic module transduces the signal for coupling to G proteins. Several constitutive, activating mutations that cause human disease have been found in helix VI and adjacent structures. These mutations have provided valuable information about mechanisms of signal transfer and G protein coupling. The structure of the LHR gene has been elucidated, and the regulation of its transcription is beginning to be understood. Valuable insights into receptor evolution have been derived from analysis of sequence homologies, the gene structure of glycoprotein hormone receptors and other members of the GPCR family, and the glycoprotein hormone receptor-like precursors identified in several invertebrate species.

Luteinizing hormone increases the abundance of various transcripts, independently of the androgens, in the rat prostate

Differential display analysis was carried out to find, in the rat prostate, genes that could be regulated by Luteinizing Hormone (LH), independently of the androgens. Hypophysectomized and castrated adult rats were treated with either LH, testosterone or saline. Regulated discrete bands have been eluted and reamplified. After Northern blotting, the levels of mRNA corresponding to 8 PCR fragments were significantly increased by LH treatment. None of these inserts were found to be induced by testosterone. One insert was subcloned, sequenced and identified as the ribosomial protein S 23. A competitive RT-PCR assay was carried out on the full length S 23 cDNA and confirmed that its mRNA levels were stimulated by LH but not by testosterone. These results strongly suggest that the LH membrane receptor, previously shown to be expressed in the rat prostate, has a physiological significance in this organ. Moreover, it appears that the effect of LH on the rat prostate are independent of the androgens.