Immunocytochemical localization of androgen receptor with polyclonal antibody in paraffin-embedded human tissues

Immunocytochemical localization of bovine serum albumin (BSA) in the liver and testis of rats injected with testosterone-BSA, hydrocortisone-BSA or corticosterone-BSA

Through observations of colloidal gold with silver enhancement, we have demonstrated that 2-nm colloidal gold labeled-testosterone-bovine serum albumin (BSA) conjugate or hydrocortisone-BSA conjugate injected intravenously enters the hormone-target cell nuclei of rats (Nishimura and Ichihara, 1997; Nishimura and Nakano, 1997, 1999). To confirm immunocytochemically whether the nature of BSA in the steroid hormone-BSA conjugates (steroid-BSAs) remains intact in the hormone-target cell nuclei, testosterone-BSA, hydrocortisone-BSA or corticosterone-BSA was injected into the vascular system of rats, then the liver and testes of rats killed 2 h postinjection were reacted with FITC-conjugated anti-BSA antibody, and examined under fluorescence microscopy and confocal laser scanning microscopy. In the liver of rat injected with testosterone-BSA, the fluorescence was observed in the nuclei of endothelial cells, but not in the nuclei of hepatocytes, hepatic stellate cells and Kupffer cells. In the liver of rat injected with hydrocortisone-BSA, intense fluorescence was seen in the nuclei of hepatic stellate cells, but did not seem to be present in the nuclei of the other three kinds of cells. In the liver of rat injected with corticosterone-BSA, the fluorescence seemed to be in a few nuclei of hepatic stellate cells, and appeared as speckles in a few nuclei of the hepatocytes and Kupffer cells. In some seminiferous tubules of rat injected with testosterone-BSA, fluorescence was observed in the nuclei of spermatocytes and spermatids. These results suggest that BSA conjugated with steroid hormone can enter the hormone-target cell nuclei with its antigenicity kept intact, and that the fate of steroid-BSAs is decided at the cell membrane level.

Estradiol acts as a germ cell survival factor in the human testis in vitro

The necessity of estrogens for male fertility was recently discovered in studies on both estrogen receptor alpha knockout and aromatase (cyp 19 gene) knockout mice. However, direct testicular effects of estrogens in male reproduction have remained unclear. Here we studied the protein expression of ERalpha and the recently described estrogen receptor beta in the human seminiferous epithelium and evaluated the role of 17beta-estradiol, the main physiological estrogen, in male germ cell survival. Interestingly, both estrogen receptors alpha and beta were found in early meiotic spermatocytes and elongating spermatids of the human testis. Furthermore, low concentrations of 17beta-estradiol (10(-9) and 10(-10) mol/L) effectively inhibited male germ cell apoptosis, which was induced in vitro by incubating segments of human seminiferous tubules without survival factors (i.e. serum and hormones). Dihydrotestosterone, which, in addition to estradiol, is an end metabolite of testosterone, was also capable of inhibiting testicular apoptosis, but at a far higher concentration (10(-7) mol/L) than estradiol. Thus, estradiol appears to be a potent germ cell survival factor in the human testis. The novel findings of the present study together with the previously reported indirect effects of estrogens on male germ cells indicate the importance of estrogens for the normal function of the testis.

Androgens and the control of skeletal muscle protein synthesis

Athletes have long supported the concept that anabolic steroids increase skeletal muscle mass. However, it was only recently that both testosterone and its synthetic analogue, oxandrolone, were proven capable of inducing myotrophic effects in postabsorptive human skeletal muscle. These findings have provided the physiological evidence that anabolic steroids deserve attention in the clinical arena as a pharmacological intervention against losses in lean body mass associated with age, disease, trauma and burn injury. However, we are lacking in vivo molecular evidence that would directly or indirectly link androgens and the androgen receptor with increases in skeletal muscle mass. Clearly, a need exists to link in vivo and in vitro studies from both the physiological and molecular arena as they relate to androgens and the control and regulation of skeletal muscle mass. In this brief review, newly discovered information and emerging theories relating to the direct, indirect, priming and antiglucocorticoid action of androgens on skeletal muscle will be presented.

FHL2, a novel tissue-specific coactivator of the androgen receptor

The control of target gene expression by nuclear receptors requires the recruitment of multiple cofactors. However, the exact mechanisms by which nuclear receptor-cofactor interactions result in tissue-specific gene regulation are unclear. Here we characterize a novel tissue-specific coactivator for the androgen receptor (AR), which is identical to a previously reported protein FHL2/DRAL with unknown function. In the adult, FHL2 is expressed in the myocardium of the heart and in the epithelial cells of the prostate, where it colocalizes with the AR in the nucleus. FHL2 contains a strong, autonomous transactivation function and binds specifically to the AR in vitro and in vivo. In an agonist- and AF-2-dependent manner FHL2 selectively increases the transcriptional activity of the AR, but not that of any other nuclear receptor. In addition, the transcription of the prostate-specific AR target gene probasin is coactivated by FHL2. Taken together, our data demonstrate that FHL2 is the first LIM-only coactivator of the AR with a unique tissue-specific expression pattern.

Immunolocalization of androgen receptors in testicular cells during postnatal development of the bank vole (Clethrionomys glareolus, S.)

Determination of the cellular distribution of the androgen receptors within the testis is of great importance for an understanding of their essential role in mediating of androgen action in the male gonad. In bank voles, which are seasonally breeding rodents, photoperiod is one of the most important factors inducing profound changes in the morphology and hormonal activity of the testes. Immunolocalization of androgen receptors was found in all somatic cells such as Sertoli cells, Leydig cells, and peritubular-myoid cells, however, distribution of the androgen receptors in various cell types depended on age of animals. Intensity of immunoreactivity was noticed as age and photoperiod-dependent. Males reared under different light regimes showed a significant correlation between the length of light and sexual maturation. Therefore, morphology of the testis from young and adult bank voles was also presented.

Monoclonal anti-androgen receptor antibodies: production, characterization and potential diagnostic applications

Several monoclonal antibodies (mAbs) and novel mAb-based assays for the androgen receptors (AR) have been developed. Large amounts of the recombinant human AR protein produced by a baculovirus expression system were used as an antigen to produce mAbs. Twenty-nine AR-specific mAbs were first confirmed by Western blot analysis and were then characterized for their immunoglobulin isotypes, epitopes, and epitope localization in AR. Novel assays using flow cytometry and sandwich enzyme-linked immunosorbent assays (ELISA) were established to detect AR-expressing cells and to quantify soluble AR protein, respectively. Using immunostaining, we identified several anti-AR mAbs exclusively recognizing AR within the nuclei of the prostate cancer cell line LNCaP and of prostate tissues in both frozen and paraffin-embedded sections, whereas other mAbs could detect AR in both nuclear and cytoplasmic compartments. Interestingly, certain mAbs, such as G122-25 and G122-77, could distinguish the androgen-bound AR from the unoccupied AR. In sum, many purified AR protein and anti-AR mAbs, together with the assays developed, could be powerful tools for the study of functional AR and for the diagnosis of prostatic cancers.

Identification and cloning of a novel androgen-responsive gene, uridine diphosphoglucose dehydrogenase, in human breast cancer cells

Androgens inhibit the growth of breast cancer cells, but the mechanism of androgen-induced growth inhibition has not yet been elucidated, and few androgen-responsive genes have been identified. We, therefore, used differential display PCR to identify novel androgen-responsive genes in ZR-75-1 human breast cancer cells. The human UDP-glucose dehydrogenase gene (UDPGDH), which was not known to be androgen regulated, was detected and cloned by complementary DNA library screening. The UDPGDH open reading frame codes for a protein of 494 amino acids that migrates at an apparent molecular mass of approximately 54 kDa. Northern blot analysis revealed the existence of two messenger RNA species of approximately 3.5 and 2.7 kb in all of the human breast cancer cell lines examined. The major UDPGDH transcript was induced rapidly (within 6 h) by dihydrotestosterone in ZR-75-1 cells, and a maximal 13-fold induction was observed after 24 h of treatment. The increase in UDPGDH messenger RNA was completely prevented by coincubation with the pure antiandrogen hydroxyflutamide, but not by cycloheximide, indicating that UDPGDH is directly regulated by the androgen receptor. As UDPGDH is required for the production of uridine 5'-diphosphoglucuronic acid, a substrate for the steroid-conjugating uridine diphospho-glucuronosyltransferase enzymes, up-regulation of UDPGDH expression by androgens might play an important role in the control of sex steroid inactivation via glucuronidation in breast cancer cells.

Short-term oxandrolone administration stimulates net muscle protein synthesis in young men

Short term administration of testosterone stimulates net protein synthesis in healthy men. We investigated whether oxandrolone [Oxandrin (OX)], a synthetic analog of testosterone, would improve net muscle protein synthesis and transport of amino acids across the leg. Six healthy men [22+/-1 (+/-SE) yr] were studied in the postabsorptive state before and after 5 days of oral OX (15 mg/day). Muscle protein synthesis and breakdown were determined by a three-compartment model using stable isotopic data obtained from femoral arterio-venous sampling and muscle biopsy. The precursor-product method was used to determine muscle protein fractional synthetic rates. Fractional breakdown rates were also directly calculated. Total messenger ribonucleic acid (mRNA) concentrations of skeletal muscle insulin-like growth factor I and androgen receptor (AR) were determined using RT-PCR. Model-derived muscle protein synthesis increased from 53.5+/-3 to 68.3+/-5 (mean+/-SE) nmol/min.100 mL/leg (P < 0.05), whereas protein breakdown was unchanged. Inward transport of amino acids remained unchanged with OX, whereas outward transport decreased (P < 0.05). The fractional synthetic rate increased 44% (P < 0.05) after OX administration, with no change in fractional breakdown rate. Therefore, the net balance between synthesis and breakdown became more positive with both methodologies (P < 0.05) and was not different from zero. Further, RT-PCR showed that OX administration significantly increased mRNA concentrations of skeletal muscle AR without changing insulin-like growth factor I mRNA concentrations. We conclude that short term OX administration stimulated an increase in skeletal muscle protein synthesis and improved intracellular reutilization of amino acids. The mechanism for this stimulation may be related to an OX-induced increase in AR expression in skeletal muscle.

Regulation of lutenizing hormone secretion and subunit messenger ribonucleic acid expression by gonadal steroids in perifused pituitary cells from male monkeys and rats

The mechanisms by which gonadal steroids regulate gonadotropin secretion remain incompletely understood. As previous studies suggest that the pituitary actions of testosterone (T) and estradiol (E) differ in male primates and rodents, we compared the effects of 10 nM T, 0.1 nM E, and 10 nM dihydrotestosterone (DHT) on the LH response to hourly pulses of GnRH as well as the GnRH receptor (GnRH-R) and LH subunit messenger RNA (mRNA) levels in dispersed pituitary cells from intact male monkeys and rats. T suppressed (P < 0.01) and E increased (P < 0.05) GnRH-stimulated LH secretion by rat pituitary cells. With monkey pituitary cells, on the other hand, there was no significant effect of either T or DHT on GnRH-stimulated LH secretion. In E-treated monkey cells, a period of initial enhancement (P < 0.05) was followed by significant suppression (P < 0.05) of LH secretion. GnRH-R mRNA was unchanged by T or E in either rat or monkey cells. T suppressed LHbeta (P < 0.01) and alpha-subunit (P < 0.01) mRNAs, whereas E increased alpha-subunit (P < 0.01), but did not alter LHbeta mRNA levels in rat cells. In monkey cells, however, neither T nor E affected LHbeta or alpha-subunit mRNA levels significantly. Our results identify different regulatory mechanisms by which testicular steroid hormones control LH secretion by the pituitary in male primates and rodents. We propose that the primary site of androgen negative feedback in the male primate is to restrain GnRH pulsatile secretion, whereas in the male rat T also decreases gonadotropin synthesis and secretion by directly affecting the pituitary. E suppresses GnRH-stimulated LH secretion in the primate pituitary, but amplifies the action of GnRH in the rat. Our data also reveal that the action of T to suppress LH secretion and subunit mRNA in male rats is not through decreased GnRH-R gene expression.

Identification of ARA70 as a ligand-enhanced coactivator for the peroxisome proliferator-activated receptor gamma

In an effort to understand transcriptional regulation by the peroxisome proliferator-activated receptor gamma (PPARgamma), we have investigated its potential interaction with coregulators and have identified ARA70 as a ligand-enhanced coactivator. ARA70 was initially described as a coactivator for the androgen receptor (AR) and is expressed in a range of tissues including adipose tissue (Yeh, S., and Chang, C. (1996) Proc. Natl. Acad. Sci. U. S. A. 93, 5517-5521). Here we show that ARA70 and PPARgamma specifically interact by coimmunoprecipitation and in a mammalian two-hybrid assay. PPARgamma and ARA70 interact in the absence of the PPARgamma ligand 15-deoxy-Delta12,14-prostaglandin J2, although the addition of exogenous ligand enhances this interaction. Similarly, in transient transfection of DU145 cells, cotransfection of PPARgamma and ARA70 induces transcription from reporter constructs driven by either three copies of an isolated PPAR response element or the natural promoter of the adipocyte fatty acid-binding protein 2 in the absence of exogenous 15-deoxy-Delta12,14-prostaglandin J2. However, this PPARgamma-ARA70 transactivation is enhanced by the addition of ligand. Thus, ARA70 can function as a ligand-enhanced coactivator of PPARgamma. Finally, we show that AR can squelch PPARgamma-ARA70 transactivation, which suggests that cross-talk may occur between PPARgamma- and AR-mediated responses in adipocytes.

Immunocytochemical localization of type 5 17beta-hydroxysteroid dehydrogenase in human reproductive tissues

17beta-hydroxysteroid dehydrogenase (17beta-HSD) controls the last step in the formation of all androgens and all estrogens. At least six 17beta-HSD isoenzymes have been identified. The recently cloned Type 5 17beta-HSD transforms 4-dione into testosterone. To gain a better understanding of the role of this enzyme in reproductive tissues, we immunocytochemically localized the enzyme in human male and female reproductive organs. In the ovary of adult premenopausal women (25-40 years of age), immunostaining was found in corpus luteum cells. In the uterus, staining was detected only in the epithelial cells of the endometrium. Immunolabeling was also detected in the mammary gland, a positive reaction being detected in epithelial cells of acini and intralobular ducts as well as in the surrounding stromal cells. In the testis, strong staining was seen in the Leydig cells, and a weak but specific reaction was occasionally detected in Sertoli and germ cells. In the prostate, specific labeling was observed in alveoli and stromal fibroblasts. In alveoli, all the basal cells were generally labeled, whereas the luminal cells exhibited variations in immunoreactivity. In all the reproductive organs examined, specific staining was routinely detected in the walls of blood vessels, including the endothelial cells. These results indicate a cell-specific localization of Type 5 17beta-HSD in the different human reproductive organs, thus suggesting new mechanisms of local androgen and estrogen formation that may play an important physiological role.

Expression of pepsinogen II with androgen and estrogen receptors in human prostate carcinoma

The expression of pepsinogen II (PG II), an aspartyl proteinase usually involved in the digestion of proteins in the stomach, was immunohistochemically investigated in conjunction with androgen (AR) and estrogen receptor (ER) status in prostate adenocarcinomas. Of a total of 38 samples obtained from radical prostatectomies, 23 tumors (60.5%) were positive for PG II and there was a significant positive correlation to the expression of AR but not to ER. Cells positive for PG II were localized mainly to the peripheral zones of tumorous glands which, in normal prostate, are negative, and in areas also expressing AR. In addition, a significant correlation between AR and ER was detected in the prostate carcinomas examined, which suggests a hormone-dependent status. On the basis of these results, PG II expression might be closely related to hormonal alterations associated with the development of prostate tumors.

Androgen receptor distribution in adult human testis

The distribution of the androgen receptor (AR) in archival human testes was determined immunocytochemically using an affinity-purified peptide-specific rabbit antibody, PG21, and employing a modified biotin-streptavidin-immunoperoxidase method that incorporated a biotin amplification step. In combination with microwave epitope retrieval, the biotin amplification step increased the sensitivity of the immunostaining assay approximately 20-fold. Thus, the useful range at which PG21 rendered a robust, specific immunostaining signal without also increasing nonspecific background was extended dramatically. Broadening the useful range of the PG21 antibody made it possible to resolve the relative amounts of immunopositive AR in different cell types of the human testis. At a high PG21 concentration, for example, all AR-positive cells exhibited a robust immunostaining intensity, but it was not possible to distinguish between nuclei exhibiting either high or moderate immunostaining intensities. In contrast, as the concentration of PG21 was decreased, distinct populations of testicular cells exhibited differential AR immunostaining intensities in their nuclei. AR immunostaining of Sertoli cell nuclei was present at low PG21 concentrations at which no immunostaining of peritubular myoid cells or Leydig cells could be detected. In turn, AR immunostaining of peritubular myoid cells was detected at PG21 concentrations that did not immunostain Leydig cells. Moreover, within the seminiferous epithelium, Sertoli cell nuclear AR staining intensity was less at stages V and VI of the cycle of the seminiferous epithelium than that at stage III, and stage III staining intensity was greater than that at stages I and II. This AR immunostaining pattern in human Sertoli cell nuclei as a function of the cycle of the seminiferous epithelium is reminiscent of the pattern observed in rodent species. Finally, no AR immunostaining of germ cells was observed at any of the PG21 concentrations examined.

Androgen receptor gene expression in the primate ovary: cellular localization, regulation, and functional correlations

Excess androgens are associated with a characteristic polyfollicular ovarian morphology; however, it is not known to what extent this problem is due to direct androgen action on follicular development vs. interference with gonadotropin release at the level of the pituitary or hypothalamus. To elucidate potential androgen effects on the ovary, we investigated the cellular localization of androgen receptor (AR) messenger ribonucleic acid (mRNA) in rhesus monkey using in situ hybridization. To investigate the regulation of ovarian AR gene expression, we compared the relative abundance of AR transcripts in monkeys during follicular and luteal phases of the menstrual cycle and in monkeys treated with testosterone. To assess potential functional consequences of AR expression in the primate ovary, we compared AR mRNA levels with indexes of follicular cell proliferation and apoptosis in serial sections from individual follicles. AR mRNA expression was most abundant in granulosa cells of healthy preantral and antral follicles in the primate ovary. Theca interna and stromal cells also expressed AR mRNA, but to a lesser degree than granulosa cells. No significant cycle stage effects were noted in AR mRNA levels; however, larger numbers of animals would be necessary to definitively establish a cycle stage effect. AR mRNA level was significantly increased in granulosa cells and was decreased in theca interna and stromal cells of testosterone-treated monkeys. Importantly, granulosa cell AR mRNA abundance was positively correlated with expression of the proliferation-specific antigen Ki-67 (r = 0.91; P < 0.001) and negatively correlated with granulosa cell apoptosis (r = -0.64; P < 0.001). In summary, these data show that primate ovary AR gene expression is most abundant in granulosa cells of healthy growing follicles, where its expression is up-regulated by testosterone. The positive correlation between granulosa AR gene expression and cell proliferation and negative correlation with programmed cell death suggests that androgens stimulate early primate follicle development.

Physiology and pathophysiology of androgen action

Knowledge of the physiology of male sexual differentiation and the clinical presentation of androgen insensitivity syndromes (AIS) has led to an increasing understanding of the mechanisms of androgen action. Androgens induce their specific response via the androgen receptor (AR), which in turn regulates the transcription of androgen-responsive target genes. The androgen-dependent development of male genital structures and the induction of the normal male phenotype depends on the presence of an intact AR. Structural alterations leading to malfunction of the AR are associated with variable inhibition of virilization despite normal or even supranormal serum levels of androgens. The mapping, cloning and sequencing of the AR gene have facilitated new insights into the study of androgen action. Functional investigation of the normal and the mutant AR in vivo as well as in vitro has led to the characterization of the distinct molecular steps involved in the normal androgen action pathways that are inhibited in the androgen insensitivity syndrome.

Estrogen and progesterone receptors in androgenic alopecia versus alopecia areata

In some situations, hair growth is under hormonal control. Androgenic alopecia is characterized as hormonally driven hair loss in the genetically susceptible individual. During pregnancy, hair growth is increased, as estrogen appears to prolong the anagen phase. However, postpartum hair loss is common, and thus may be related to a decrease in estrogen and or progesterone levels. In contrast, alopecia areata is not considered to be under hormonal control. We compared the immunohistochemical staining characteristics of nine cases of androgenic alopecia with those of 13 cases of alopecia areata using estrogen receptor (ER) and progesterone receptor (PR) markers. Estrogen receptor positivity in the dermal papilla was found in only two of 13 cases of alopecia areata, and in one case of androgenic alopecia. Six of 13 cases of alopecia areata demonstrated focal reactivity with the progesterone marker in a similar location, while only three cases of androgenic alopecia showed positivity with this antibody. Examination of the perifollicular fibroblasts for the ER marker showed positivity in one of 13 cases of alopecia areata and in one case of androgenic alopecia. Two cases of alopecia areata revealed focal staining in this location for the PR marker, while the androgenic alopecia cases failed to stain. These results indicate that estrogen and progesterone receptor expression is not significantly increased or decreased in the pilosebaceous units or surrounding mesenchymal cells in androgenic alopecia vs. alopecia areata. Therefore, an indirectly mediated process of estrogen/progesterone control on hair growth and development must be presumed for cases of androgenic alopecia.

Evidence for a stimulatory role of follicle-stimulating hormone on the spermatogonial population in adult males

OBJECTIVE

To evaluate the effects of treatment with FSH on seminal indices and on the seminiferous epithelium of oligozoospermic subjects with normal FSH plasma levels.

DESIGN

Placebo-controlled, double-blind randomized study.

SETTING

Academic setting.

PATIENT(S)

Ninety subjects with idiopathic oligozoospermia (sperm count of < 10 x 10(6)/mL) and normal plasma levels of FSH.

INTERVENTION(S)

Three months of treatment with FSH (60 patients) or placebo (30 patients); bilateral testicular fine-needle aspiration.

MAIN OUTCOME MEASURE(S)

Seminal indices; testicular cytologic features; plasma levels of FSH, LH, and testosterone; and ultrasonographic testicular examination.

RESULT(S)

According to seminal indices, patients treated with FSH and placebo were classified as nonresponders or as responders (as determined by at least a doubling of sperm count). No placebo-treated patients responded to treatment. Among FSH-treated patients, 20 responded to hormonal treatment and 40 did not. The results of pretreatment cytologic examination of testicular specimens from patients who did not respond to FSH treatment were consistent with hypospermatogenesis associated with maturational disturbances at the spermatid level. In contrast, patients who responded to treatment with FSH had isolated hypospermatogenesis without maturational disturbances. After FSH therapy, we detected an increase of spermatogonia and spermatocyte population in both the responder and nonresponder subjects. This increase was associated with an activation of spermatogenic and spermiogenic processes and with a rise in ejaculated sperm concentration only when isolated hypospermatogenesis was present (responder patients).

CONCLUSION(S)

The findings of this study demonstrate that FSH treatment increases the spermatogonial population in men. This treatment may be appropriate for oligozoospermic subjects who have normal FSH plasma levels and a testicular evaluation characterized by hypospermatogenesis without maturational disturbances.

Regulation of androgen and estrogen receptors in male excurrent ducts of the goat: an immunohistochemical study

BACKGROUND

Since androgens and/or estrogens must bind with specific receptors in order to elicit a response at the target organ(s), it is important to understand factors that regulate expression of androgen receptors (AR) and estrogen receptors (ER). Hence, the objective of the study is to determine the relative significance between circulating androgen (CA) and luminal androgen (LA) in maintaining normal expression of AR and ER in male excurrent ducts.

METHODS

Mature Nubian goats were subjected for 15 days each to the following treatments: (1) bilateral orchidectomy, (2) bilateral orchidectomy and testosterone treatment, (3) unilateral ligation of the extratesticular rete, and (4) unilateral orchidectomy. Tissues from different segments of the excurrent ducts were fixed in 4% paraformaldehyde and embedded in Paraplast-plus. Antigenic sites for AR and ER were immunolocalized using PG-21 rabbit antirat/human antibody and H-222 rat antihuman monoclonal antibody, respectively. The avidin-biotin horseradish peroxidase procedure was used to identify positive immunoreactivity. Negative controls included incubation of sections with irrelevant IgG in place of primary antibody.

RESULTS

In intact animals, whereas AR were found in epithelial, connective tissue, and peritubular smooth muscle cells of the efferent ductules, regions I-V of the epididymis, and ductus deferens, ER were confined to nonciliated cells of the efferent ductules. Bilateral orchidectomy caused a severe loss of both AR and ER staining. Testosterone replacement to orchidectomized animals restored staining of both AR and ER to the intact level. Neither unilateral ligation of the extratesticular rete nor unilateral orchidectomy had any effect on AR or ER immunostaining.

CONCLUSION

Circulating androgen alone, without any input from luminal androgen or other rete fluid contents, can regulate expression of both androgen receptor and estrogen receptor.

Role of the androgen receptor in human breast cancer

Although the androgen receptor (AR)3 is often co-expressed with the estrogen receptor (ER) and progesterone receptor (PR) in human breast tumors, its role in breast cancer is poorly understood. Specific growth stimulatory and inhibitory actions of androgens have been described in human breast cancer cell lines. The mechanisms by which androgens exert these contrasting growth effects are unknown. A commonly utilized second line therapy for the treatment of advanced breast cancer is high dose medroxyprogesterone acetate (MPA). Although MPA, a synthetic progestin, was thought to act exclusively through the PR, the androgenic side-effects observed in women taking MPA suggest that its action may also be mediated in part by the AR. In support of this hypothesis, the level of AR measured by radioligand binding in primary breast tumors was correlated with the duration of response to MPA treatment following failure of tamoxifen therapy. Recent data suggest that the presence of structurally altered AR in breast cancers may account for unresponsiveness to MPA in some of these cases. Further studies are warranted to determine the role of AR mediated pathways in regulating breast tumor growth. In particular, identification of androgen-regulated genes may lead to new possibilities for the hormonal treatment of breast cancer.

The localization of androgen receptors in human bone

Androgens have important effects on the human skeleton, and deficiency has been associated with bone loss in both males and females. The skeletal actions of androgens may be mediated directly via the androgen receptor (AR) or indirectly via the estrogen receptor after aromatization to estrogens. The presence of androgen receptors has been demonstrated in bone cells and chondrocytes in vitro, but their presence in human bone in situ has not been reported. In order to provide further evidence for a direct action of androgens on bone via androgen receptors, we have used specific monoclonal antibodies to investigate the expression of human AR in normal developing and osteophytic bone of both sexes. In the growth plates from the developing bone, androgen receptors were predominantly expressed in hypertrophic chondrocytes and in osteoblasts at sites of bone formation. They were also observed in osteocytes in the bone, and in mononuclear cells and endothelial cells of blood vessels within the bone marrow. In the osteophytes, androgen receptors were widely distributed at sites of endochondral ossification in proliferating, mature, and hypertrophic chondrocytes and at sites of bone remodeling in osteoblasts. They were also expressed in osteocytes and mononuclear cells within the bone marrow. The pattern and number of cells expressing the receptor was similar in both sexes. Our results show for the first time the presence and distribution of androgen receptors in normal developing human and osteophytic bone in situ and further provide evidence for a direct action of androgens on bone and cartilage cells.

Immunolocalization of androgen receptor and estrogen receptor in the developing testis and excurrent ducts of goats

BACKGROUND

Because of the significance of androgens and estrogens in prenatal and postanatal differentiation of the testis and excurrent ducts, it is important to understand the developmental pattern of androgen receptor (AR) and estrogen receptor (ER) in these organs.

METHODS

Tissues from 1-23-week-old goats were fixed in 4% paraformaldehyde and embedded in Paraplast-plus. Antigenic sites for AR and ER were immunolocalized using the PG-21 rabbit anti-rat/human antibody and the H-222 rat anti-human monoclonal antibody, respectively. The avidin-biotin horseradish peroxidase procedure was used to identify positive immunoreactivity. Controls included incubation of sections with irrelevant IgG in place of primary antibody.

RESULTS

Within the testis, immunostaining for AR in the nuclei of Sertoli cells increased gradually from mild at week 1 to strong at week > or = 19. In contrast, nuclei of peritubular myoid cells and Leydig cells exhibited moderate to strong reaction for AR in all animals. Germ cells were negative. Within the rete testis, efferent ductules, regions I-V of the epididymis, and ductus deferens, nuclei of all epithelial cells, peritubular myoid cells, and intertubular connective tissue cells expressed moderate to strong staining for AR at all ages. ER were confined to nonciliated cells of the efferent ductules, which displayed moderate staining in all animals, beginning from week 1.

CONCLUSIONS

Nuclear AR staining, found in all testicular cells (except germ cells) and excurrent duct cells examined, was observed to change in an age-related manner only in Sertoli cells, where staining intensity increased between week 1 and week 19. Staining for ER, confined to nonciliated epithelial cells of the efferent ductules, was not affected by postnatal age.

Human prostatic smooth muscle cells in culture: estradiol enhances expression of smooth muscle cell-specific markers

Smooth muscle cells (SMCs) constitute a major cellular component of prostatic stroma. SMC tension plays an important role in urethral obstruction secondary to benign prostatic hyperplasia (BPH). We have developed an in vitro procedure for the propagation of human prostatic SMCs. Tissue specimens from patients undergoing radical prostatectomy or cystectomy were enzymatically disaggregated and cultured in MCDB-131 medium supplemented with horse serum, insulin, conditioned medium from the tumor cell line CRL-5813, and steroid hormones. The medium was assembled on the basis of the effects these supplements have on the growth of SMC cultures and on the expression of the two markers desmin and smooth muscle myosin. Addition of 0.1 microM of estradiol to the growth medium dramatically increased expression of these SMC-specific markers. Dihydrotestosterone (DHT) and hydrocortisone had a similar, albeit less pronounced effect. At three to five passages, about two thirds of the cells were immunohistologically positive for smooth muscle myosin or desmin. Almost all cells were positive for the myofibroblast marker smooth muscle alpha-actin throughout 10 passages and more. In SMC cultures, cells staining for smooth muscle myosin and desmin were found to seek direct contact to myofibroblasts. They grew in aggregates on a layer of myofibroblasts which adhered to the surface of the culture vessel. As revealed by transmission electron microscopy the cultured cells exhibited morphological features of myofibroblasts. Characteristics of smooth muscle cells, such as prominent bundles of microfilaments associated with dense bodies, basal laminae investing the cells, and numerous caveolae at the cell surfaces were regularly observed in cultures of low passages. After several passages, these features were markedly decreased and organelles of the biosynthetic system became more prominent. In summary, we present an in vitro model of prostatic SMCs and demonstrate that steroid hormones have characteristic effects on these cells. SMC cultures are expected to facilitate investigation of the functions and properties of human prostatic SMCs.

Pituitary Sex Steroid Receptors: Localization and Function

The pituitary contains estrogen receptor (ER), progesterone receptor (PR), and androgen receptor (AR). In accordance with immunocytochemistry, it is agreed that sex hormone receptors reside into the nucleus. All three receptors are found predominantly in gonadotrophs and lactotrophs, and less frequently in other cell types. ER plays a major role in prolactin (PRL) production and lactotroph proliferation, and protracted estrogen administration induces lactotroph hyperplasia and adenoma in rodents. Most research on PR and AR is focused on their role in the fine-tuning of gonadotropin secretion during estrous cycle. Contrary to the effect in nontumorous pituitary, estrogens can inhibit the proliferation of transplantable rat pituitary tumors and of cell lines derived from them. In humans, despite the presence of ER in all types of adenohypophysial tumors, the role of estrogen in tumor cell proliferation is still unclear. Few results indicate that tumor growth is stimulated by estrogen, and inhibited by progesterone and androgen. Novel data reveal that steroid hormones can act directly on plasma membrane or via other receptors, and interact with growth factors, oncogenes, and other transcription factors. The mechanisms by which steroid hormones control cell proliferation remain a major challenge for future research.

Expression of the androgen receptor and an androgen-responsive protein, apolipoprotein D, in human breast cancer

Little is known regarding the activity and function of the androgen receptor (AR) in human breast cancer. In the present study AR was evaluated in untreated primary breast cancers using antisera to the amino- and carboxy-termini of the receptor and quantitated using colour video image analysis. A strong correlation between tissue concentration and percentage AR-positive cells was observed for each antiserum. However, comparison of percentage positive cells using the amino- and carboxy-terminal AR antisera in individual breast cancer specimens revealed a subset of tumours with discordantly increased staining for the carboxy terminus. These findings suggest the presence of amino-terminal-truncated AR in a proportion of breast cancer cells or presence of AR mutations or associated protein alterations that affect binding of the amino-terminal AR antiserum. Immunohistochemical expression of the androgen-regulated glycoprotein, apolipoprotein D (apo-D), was also evaluated in the breast cancer specimens. Focal positivity of apo-D staining, which did not always co-localise with AR-positive cells, was observed within breast tumours. Furthermore, no correlation was evident between percentage positive cells stained for AR and apo-D in breast cancer specimens. These findings indicate that, although apo-D expression is androgen regulated in human breast cancer cell lines in vitro, its expression in primary breast cancers may be regulated by other factors. The expression of AR in primary breast cancers also suggests that the receptor may be involved in tumour responsiveness or in abnormal responses to endocrine therapies.

Immunohistochemical localization of androgen receptor in mouse testicular germ cells during fetal and postnatal development

BACKGROUND

Determination of the cellular distribution of the androgen receptor (AR) in testicular cells is necessary for understanding the mode of AR action in the testis. We here investigated immunohistochemically the localization of AR by use of anti-human AR polyclonal antibody NH27, with special reference to the AR in germ cells in the developing mouse testis.

METHODS

ICR mouse testes taken from day 14 post coitum (p.c.) to day 56 post partum (p.p) were used for AR immunohistochemistry by the routine immunoperoxidase method at the light microscopic level and the pre-embedding method at the electron microscopic level.

RESULTS

On day 14 p.c., AR immunoreactivity was present in nuclei of prospermatogonia but not in those of Sertoli cells or interstitial cells. On day 14 p.p., the AR was detected in the nuclei of spermatogonia, Sertoli cells, and myoid cells. AR immunoreactivity in nuclei of Leydig cells appeared on day 21 p.p. In the mature mouse testis, the AR was present in the nuclei of spermatogonia, Sertoli cells, myoid cells, and Leydig cells.

CONCLUSIONS

AR was present both in germ cells and in somatic cells during fetal and postnatal development of the mouse testis. In the fetal testis, AR was localized exclusively in prospermatogonia and spermatogonia, suggesting that androgen may act directly on germ cells during prespermatogenesis and the early stage of spermatogenesis. Based on the fact that AR is expressed in Sertoli cells, myoid cells, and Leydig cells around the onset of spermatogenesis, the regulation of AR expression in the germ cells seems to be different from that in the somatic cells. Furthermore, our present data suggest the ultrastructural localization in nuclei of mouse testicular cells is similar to that of some other steroid receptors, both in germ cells and somatic cells.

Characteristics of androgen-independent growth of androgen-responsive Shionogi carcinoma 115 cells

BACKGROUND

The effects of castration on the biological features of an androgen-responsive carcinoma were examined in order to clarify the mechanism responsible for the relapse of an androgen-responsive carcinoma after androgen ablation therapy.

METHODS

A well-characterized androgen-responsive mammary carcinoma, Shionogi carcinoma 115 (SC115), was used for these experiments. Male mice were examined for the effects of castration on the growth rate of the tumor, the number of androgen receptor-positive cells, and the karyotype of the SC115 tumors. Castration was performed 1 week prior to tumor transplantation, or 2 or 3 weeks after tumor transplantation.

RESULTS

SC115 tumors did not develop when transplanted into castrated male mice. When castration was performed 2 weeks after transplantation, the tumor showed androgen-independent growth with temporary regression of growth rate. However, when castration was performed more than 3 weeks after transplantation, the tumor showed androgen-independent growth not associated with any temporal regression of growth rate. There were no significant differences in histological features or the number of androgen receptor-positive cells between SC115 tumors in untreated or castrated mice. To test whether SC115 tumors growing under androgen-deprived conditions became fully androgen-independent, SC115 tumors were transplanted in both male and female mice. A transplanted tumor piece grew progressively only in male mice. This indicates that the SC115 tumor maintains its androgen response in the next generation, even though growth of the tumor resumed after temporary suppression due to castration. Chromosomal analyses revealed no apparent cytogenetic changes in the SC115 tumors that resumed growth under androgen-deprived conditions.

CONCLUSION

These results suggest that no gross changes in the number of androgen receptor-positive cells or karyotype are necessary for androgen-independent growth in this system once the size of tumor increased.

A and B forms of the androgen receptor are expressed in a variety of human tissues

Human genital skin fibroblasts contain both the full-length 110 K androgen receptor protein (AR-B, apparent M(r) approximately 110,000) and an 87 K N-terminally truncated AR isoform (AR-A, apparent M(r) approximately 87,000). These two AR species are structurally analogous to the A- and B-isoforms of the progesterone receptor (PR). We examined the distribution pattern of human AR isoforms in a variety of fetal and adult tissues by Western blot analysis. Relative levels of immunoreactive AR proteins in high salt tissue extracts were estimated by densitometry in comparison to a standard normal genital skin fibroblast preparation. High AR levels (AR-A + AR-B = 0.8-7.7) were present in male and female reproductive tissues from mid-trimester fetuses, including penis, prostate, testis, epididymis, scrotal skin, labial skin, uterus/cervix, and ovary. AR-A and AR-B (0.08-0.9) also were found in 14 non-genital fetal tissues (bladder, fat, lung, great vessel, trachea, muscle, scalp skin, kidney, thyroid, intestine, thymus, ureter, stomach and rectum). AR-A accounted for 4-26% of the AR protein detected in these tissues. Ten other fetal tissues had low levels of AR-B (0.02-0.3) and little or no detectable AR-A. AR-B also was the predominant or only immunoreactive AR species found in 17 adult human tissues. AR levels in adult reproductive tissues (prostate, endometrium, ovary, uterus, fallopian tube, testis, seminal vesicle, myometrium, and ejaculatory duct) ranged from 0.1 to 2.2. Immunoreactive AR (0.4-0.8) also was present in specimens of prostate carcinoma, endometrial carcinoma, thyroid carcinoma and kidney. Lower levels of AR (0.03-0.1) were detected in adult breast, colon, lung and adrenal gland specimens. This study demonstrates that immunoreactive AR protein is present in a wide variety of human fetal and adult tissues and that two AR isoforms are expressed in many tissues.

In vitro models for the effects of sex hormones on neurons

The results of these two in vitro models share some striking similarities. In both, estrogen was able to induce or promote the formation of either dendrites themselves in hippocampal neurons or dendritic specializations in PC12 neurites, and these specializations were then able to induce interneural interactions. In both models, androgen was able to promote the development of axons that branched frequently, while not directly fostering interneuronal contact. These findings recapitulate in part some of the effects of estrogen and androgen on neurons in vivo and suggest the inherent ability of cells of neural crest origin to respond to these hormones with specific neural morphogenetic programs designed to alter interneuronal communication. In these ways, it seems likely that both sex hormones are acting as neural growth factors in cells that express the appropriate receptor, leading to stereotyped changes in neural growth and pattern formation. Through the examination of such subcellular mechanisms, we hope to further understand the effects of sex hormones on brain development and the ontogeny of behavioral, cognitive, and reproductive differences between the sexes.

Androgen regulation of the messenger RNA encoding diazepam-binding inhibitor/acyl-CoA-binding protein in the rat

Our recent finding that diazepam-binding inhibitor/acyl-CoA-binding protein (DBI/ACBP) expression is regulated by androgens in the human prostatic adenocarcinoma cell line LNCaP, prompted us to study whether androgen regulation of DBI/ACBP also occurs in vivo in the prostate and in other organs of the rat. Northern blot analysis demonstrated that DBI/ACBP transcripts were expressed in male accessory sex organs such as ventral prostate, dorsolateral prostate, seminal vesicles and coagulating glands. Castration caused a 1.7- to 2.7-fold reduction in the levels of DBI/ACBP transcripts over a period of 6 days. Readministration of androgens during the last 3 days led to 4.2- to 7.5- fold higher levels of DBI/ACBP transcripts than in untreated castrates. In situ hybridization revealed that in the ventral prostate, DBI/ACBP transcripts were expressed predominantly in epithelial cells and that the observed effects of androgens were due both to modulation of gene expression per cell and to changes in cell composition. Androgen regulation of DBI/ACBP mRNA expression was also observed in the lacrimal glands, the adrenals, and the submandibular glands, but not in the liver and the kidney. These findings demonstrate that DBI/ACBP is androgen-regulated in vivo in various organs of the rat. In view of the proposed role of DBI/ACBP in the control of multiple biological processes, DBI/ACBP may be one of the target genes by which androgens affect a variety of physiological processes.

Immunocytochemical demonstration of androgen receptors in Leydig cells of the bank vole (Clethrionomys glareolus, Schreber): an in vitro study

Androgen receptors of the bank vole Leydig cells in vitro were immunostained using a polyclonal antibody against androgen receptors followed by streptavidine-peroxidase complex or rhodamine-labelled goat anti-rabbit IgG visualization. The immunocytochemical studies revealed localization of androgen receptors in the whole cytoplasm or in the perinuclear area of the cells. Addition of dehydroepiandrosterone into the culture medium resulted in nuclear localization of the androgen receptors. Long (18L : 6D) and short (6L : 18D) photoperiods as well as the age of animals were taken into account. The concentration of androgen receptors was changed dependent on age and status of reproduction.

Immunocytochemical detection of androgen receptor in human temporal cortex characterization and application of polyclonal androgen receptor antibodies in frozen and paraffin-embedded tissues

Immunocytochemical and biochemical studies have demonstrated the presence of androgen receptor protein in various regions of the rodent and non-human primate cortex. Localization of androgen receptor in the human brain has, however, not been studied as extensively, because of difficulties in obtaining suitable tissue samples. In the present study, we have localized androgen receptors in both frozen and paraffin-embedded temporal cortex from epileptic patients undergoing resection. Polyclonal antibodies were raised against fusion proteins containing fragments of the human androgen receptor protein. The antibodies were affinity-purified against the corresponding fusion protein. Immunoprecipitation and Western blotting using extracts from human cell lines demonstrated the specificity of the antibodies for the human androgen receptor and lack of cross-reactivity with other steroid hormone receptors. Immunocytochemistry was performed on frozen and paraffin sections of human temporal cortex and in paraffin-embedded benign hyperplastic prostates (BPH), as well as prostate and breast carcinomas, by the streptavidin-biotin-peroxidase method. Antigen-retrieval was performed in paraffin-embedded sections using microwave irradiation. Specific nuclear and cytoplasmic immunoreactivity for androgen receptor was detected in neurons, astrocytes, oligodendrocytes, and microglia cells of the temporal cortex. In contrast, only nuclear staining was observed in BPH, prostate and breast carcinomas. Immunoprecipitation of human temporal cortex lysate and subsequent Western blot analysis demonstrated the expression of a 98 kDa immunoreactive protein, slightly smaller than the reported molecular weight of the wild-type androgen receptor. These results provide further evidence for the expression of androgen receptor in the human temporal cortex. The use of these immunocytochemical techniques should enable the retrospective determination of possible changes in androgen receptor expression in a variety of archival paraffin-embedded tissues, including samples of the human central nervous system.

Androgens induce divergent proliferative responses in human breast cancer cell lines

Although the majority of primary human breast cancers express the androgen receptor (AR), the role of androgens in breast cancer growth and progression is poorly understood. We have investigated the effects of the naturally occurring androgen, dihydrotestosterone (DHT), and a synthetic non-metabolizable androgen, mibolerone, on the proliferation of six human breast cancer cell lines. The anti-proliferative and proliferative effects of androgens were only observed in cell lines that expressed the AR. Two of the AR-positive cell lines, T47-D and ZR-75-1 were growth inhibited in the presence of either DHT or mibolerone, while the proliferation of MCF-7 and MDA-MB-453 cells was increased by both androgens. Co-incubation of cultures with 1 nM DHT and a 100-fold excess of the androgen receptor antagonist, hydroxyflutamide, resulted in reversal of both inhibitory and stimulatory effects of DHT on T47-D, MCF-7 and MDA-MB-453 cell proliferation, indicating that DHT action is mediated by the AR in these lines. Hydroxyflutamide only partially reversed the DHT-induced growth inhibition of ZR-75-1 cultures, which suggests that growth inhibition of these cells may be mediated by non-AR pathways of DHT (or DHT metabolite) action. Mibolerone action on breast cancer cell growth was similar to that of DHT, with the exception that growth stimulation of MCF-7 and MDA-MB-453 cells was only partially reversed in the presence of a 100-fold excess of hydroxyflutamide. Anandron, another androgen receptor antagonist, was able to reverse all inhibitory and stimulatory actions of the androgens. AR antisense oligonucleotides reduced the level of immunoreactive AR expression in MDA-MB-453 and ZR-75-1 cells by more than 60%, but only reversed the growth inhibitory action of mibolerone in ZR-75-1 cultures. The results suggest that androgen action in breast cancer cell lines may not be solely mediated by binding of androgen to the AR. For example, metabolites of DHT with oestrogenic activity, or androgen binding to receptors other than the AR, may explain the divergent responses to androgens observed in different breast cancer cell lines.

Expression of androgen receptors in skin appendage tumors: an immunohistochemical study

Androgen receptor (AR) expression was examined in normal skin and in 52 cases of various skin appendage tumors using a monoclonal antibody (F39.4.1) raised against the N-terminal domain of human AR. Microwave oven heating in citrate buffer solution followed by immunostaining with the labeled streptavidin biotin (LSAB) method was applied to formalin-fixed paraffin-embedded sections. Immunoreactive AR was restricted to the nuclei. In normal skin, AR was consistently localized in seboblasts and in some differentiated sebocytes, and variable expression was seen in luminal epithelial cells of eccrine and apocrine glands in the secretory portion. Hair follicles and epidermis showed no reactivity. In sweat gland tumors, AR was identified focally in inner layer cells of the tubuloglandular component of ten of thirteen chondroid syringomas but the remaining tumors were nonreactive. In sebaceous gland tumors, benign tumors with mature sebaceous elements (sebaceous nevi and sebaceous adenomas) showed AR expression, but the sebaceous epitheliomas and sebaceous carcinomas lost their expression. No AR expression was observed in hair follicle tumors, except in AR-positive mature sebaceous glands incorporated into the cyst wall of steatocystomas.

Immunohistochemical Localization of Chromostatin and Pancreastatin, Chromogranin A-Derived Bioactive Peptides, in Normal and Neoplastic Neuroendocrine Tissues

Despite the widespread distribution of chromogranin A (CgA) in neuroendocrine tissues, the biological function of CgA has not yet been elucidated. The primary amino acid sequence of CgA, elucidated by cDNA analysis, has been revealed to include several pairs of basic amino acid residues that are homologous to the bioactive peptides, such as pancreastatin (PST) and chromostatin (CST). Using antibodies for human PST and CST, the immunohistochemical localization of these peptides was investigated in neuroendocrine tissues, including human pituitary glands, pancreas, adrenal medulla, various types of neuroendocrine neoplasms (13 pheochromocytomas, 10 medullary thyroid carcinomas, 11 pancreatic endocrine tumors, and 19 carcinoid tumors), and the cell line QGP-1N derived from human somatostatin-producing pancreatic endocrine tumor. Variable immunoreactive intensities of PST and CST were seen, but both peptides were detectable in all neuroendocrine tissues and in most of the neoplasms. Immunoreactivity for both PST and CST was observed in 100 and 73%, respectively, of pancreatic endocrine tumors, all pheochromocytomas, and 80 and 40%, respectively, of medullary thyroid carcinomas, as well as all nonrectal carcinoid tumors. In rectal carcinoids, cells immunoreactive for PST and CST were sparse. The distribution of PST and CST was similar to that of CgA, and it is considered that these peptides are simultaneously processed from CgA, and may play roles in autocrine and paracrine regulation on various hormones in addition to their previously known functions.

Detection of human androgen receptor mRNA in hepatocellular carcinoma by in situ hybridisation

Recent evidence suggests that anti-androgen therapy may be useful in patients with androgen receptor (AR)-positive hepatocellular carcinomas (HCC), as determined by a steroid binding assay. To evaluate the AR expression of HCC, in both histological and cytological material, we developed a non-radioisotopic in situ hybridisation (NISH) assay specific for the human AR mRNA. A synthetic oligonucleotide complementary to positions 661-695 of the human AR coding sequence was end-labelled with digoxigenin-dUTP and revealed by an alkaline phosphatase-conjugated anti-digoxigenin antibody. We analysed 22 formalin-fixed, paraffin-embedded HCC, obtained at surgery, together with the corresponding non-neoplastic liver tissues (19 cases). In six cases, cell blocks obtained by fine-needle aspiration (FNA) prior to surgery were also available. Positive controls included seminal vesicles and prostate tissues. Sixteen HCCs (73%) expressed a variable amount of AR mRNA, with the proportion of positive cells ranging from very few to more than 90%. Normal hepatocytes were stained weakly and focally in eight cases (42%). Appropriate controls, inclusive of immunohistochemical detection of the AR protein in selected cases, established the specificity of the assay. Data obtained on FNA specimens were predictive of the results on histologic material. However, in two cases the NISH assay was negative on the cytological specimen but stained rare hepatocytes within the surgically resected tumor. In conclusion, NISH is a novel procedure for rapid and specific assessment of the expression of AR in HCC tissue. Its clinical significance, in terms of predictivity of response to anti-androgen treatment, needs to be assessed in large correlative studies.

Immunocytochemical localization of androgen receptors in the scalp of the stumptail macaque monkey, a model of androgenetic alopecia

The purpose of this study was to identify the distribution of androgen receptors in the bald and hairy scalp of adult male and female stumptail macaque monkeys by light microscopic biotin-avidin immunocytochemistry with a highly purified rat monoclonal antibody against the cloned human androgen receptor. Consistent, intense nuclear and minimal cytoplasmic immunostaining was observed in several distinct cell populations of the pilosebaceous unit including the dermal papilla, hair epithelium, outer root sheath, dermal sheath, and sebaceous gland. A similar distribution of androgen receptors was found in miniaturized and terminal anagen and telogen follicles of the bald and hairy scalp, respectively. Binding of androgen receptor antibody was also detected in dermal fibroblasts, basal and intermediate layers of the interfollicular epidermis, and duct and glandular cells of eccrine sweat glands. This investigation demonstrates the presence of androgen receptors in the pilosebaceous unit of the scalp of the stumptail macaque and also shows that their distribution is comparable to that previously reported for humans.