Abstract To study the tissue-specific control of androgen receptors by circulating androgens, guinea pigs were castrated or castrated and treated with crystalline testosterone propionate. Levels of serum androgens and LH were measured and brain and peripheral tissues were collected for determination of androgen receptor levels under differing androgen states. We found that circulating androgen levels changed rapidly following castration or treatment with exogenous androgen. LH secretion was coupled to circulating androgens; high levels of androgen quickly suppressed LH secretion, whereas LH levels did not rise significantly above intact levels until 7 days following castration. Androgen receptor levels were effected by circulating androgens. Cytosolic androgen receptors (ARc) increased significantly in the preoptic area (POA), septum, anterior pituitary, prostate and seminal vesicle following castration, whereas nuclear androgen receptors (ARn) decreased significantly in the POA, septum, medial basal hypothalamus (MBH), amygdala, parietal cortex, pituitary, prostate and seminal vesicle. Exogenous androgens, which increased serum steriod levels significantly above that in intact animals, decreased ARc below control levels in MBH, amygdala, pituitary and seminal vesicle. High circulating androgens increased ARn above intact levels in the MBH, pituitary and prostate. It thus appears that circulating androgens regulate LH secretion and have profound, but tissue-specific effects on androgen receptors in the guinea pig.
Differential autoregulation of androgen receptors (AR) has been previously described for the separate lobes of the rat prostate gland. While AR are up-regulated by testosterone in the ventral, dorsal, and LP1 lateral lobes, the epithelial cells of the LP2 lateral ducts show continued expression of the AR protein following androgen withdrawal. To determine the mechanism of this differential autologous regulation, the present study examined the autoregulation of AR mRNA in the separate regions of ...
Phosphorylation of the androgen receptor (AR) in human prostate tumor cells (LNCaP) is increased by androgens. The AR is expressed as two isoforms with apparent molecular masses of 110 and 112 kDa. Metabolic labeling experiments with [32P]orthophosphate revealed that only the 112 kDa isoform is radioactively labeled. Phosphoamino acid analysis revealed only phosphorylation on serine residues. Phosphotryptic peptide analysis of human AR protein by two-dimensional peptide mapping and by reverse-ph...
Sexual differentiation of behavior and gonadotropin release in short-gestation mammalian species is affected by perinatal testosterone (T). Differentiation of dimorphic behaviors in two long-gestation species (guinea pigs and rhesus macaques) depends upon prenatal androgen exposure. The brain areas mediating gonadotropin release are not sexually differentiated in nonhuman primates, but similar information is not available for the guinea pig. To obtain new information on this subject, we treated ...
Abstract Wild-type rat androgen receptor and four of its deletion mutants were produced in insect cells using the baculovirus expression system. Inclusion of androgen, but not estrogen, progesterone, or glucocorticoid, in culture medium increased the yield of soluble androgen receptors, although the majority of receptors still remained in the insoluble form (Xie, Y.-B., Sui, Y.-P., Shan, L.-X., Palvimo, J. J., Phillips, D. M., and Janne, O. A. (1992) J. Biol. Chem. 267, 4939-4948). The wild-type...
Androgen receptors synthesized by translation in vitro form dimeric aporeceptor complexes with an androgen response element (ARE). Physiological and synthetic androgens elicit a conformational change in the receptor, which increases the mobility of receptor-ARE complexes in gel retardation assays. Neither a steroidal (cyproterone acetate) nor a non-steroidal (casodex) antiandrogen brings about the same effect and, at high concentrations, reverse the action of androgen agonists. When receptor-ago...
Abstract Androgens bind to specific high-affinity receptors (AR), thereby initiating gene transcription. We investigated the effects of testosterone (T), dihydrotestosterone (DHT), and 17β-estradiol (E 2 ) on AR transcription and binding in prostate, medial basal hypothalamus (MBH), preoptic area (POA), amygdala, hippocampus, and cortex in the rat. Androgen receptor mRNA was measured by a ribonuclease protection assay. Cytosolic and nuclear AR binding (ARc and ARn, respectively) were measured by...
Abstract To characterize central nervous system changes that occur with anabolic steroid abuse in humans, immunocytochemical localization of androgen receptors in the brains of 10 intact and 10 castrated male rats was conducted after the administration of high levels of androgenic-anabolic steroids (AAS; 14 daily injections of sesame oil or a cocktail of 2 mg/kg testosterone cypionate, 2 mg/kg nandrolone decanoate, and 1 mg/kg boldenone undecylenate). In normal intact oil-treated males, nuclear ...
#2Robert J. Handa(LUC: Loyola University Chicago)H-Index: 29
Last. Robert J. Handa(LUC: Loyola University Chicago)H-Index: 29
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To determine possible cellular mechanisms governing androgen action in the brain, we examined the hormonal regulation of androgen receptor (AR) mRNA in neural tissues by Northern blot hybridization and RNase protection analysis. While a single hybridizable species of AR mRNA of approximately 11 kb was found in the anterior pituitary gland (AP) and ventral prostate gland (VP), an additional species of AR mRNA, approximately 2 kb smaller, was revealed in neural tissues. Furthermore, in these neura...
#1John A. Resko(OHSU: Oregon Health & Science University)H-Index: 45
#2Peter B. Connolly(OHSU: Oregon Health & Science University)H-Index: 13
Last. Jerome V.A. Choate(OHSU: Oregon Health & Science University)H-Index: 11
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Aromatase activity (AA) is androgen dependent and independent in subcortical regions of the nonhuman primate brain, but the correlation of androgen receptor (AR) content with AA has not been demonstrated. Thus, we castrated 10 adult male cynomolgus monkeys (Macaca fascicularis) and divided them into 2 groups. One group (n = 6) received empty Silastic capsules, whereas the second group (n = 4) received Silastic capsules filled with testosterone (T). Animals were killed after 3 weeks. Microsomal A...
Phosphorylation of the androgen receptor in human prostate tumour cells (LNCaP) is increased by addition of androgens to intact cells. Double-label studies, using [35S]methionine incorporation into receptor protein, and [32P]P(i) to label metabolically receptor phosphorylation sites, have enabled us to determine the phosphate content, relative to receptor protein, of both nontransformed and transformed and androgen receptors generated in intact LNCaP cells. No net change in the phosphorylation o...
Last. Xianyin Zeng(Sichuan Agricultural University)H-Index: 8
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Abstract The objective was to compare effects of anti-GnRH immunization (immunocastration) versus surgical castration on hypothalamic-pituitary function in boars. Thirty-six boars were randomly divided into three groups (n = 12/group): control, surgically castrated, or immunized against GnRH at 10 wk of age (boostered 8 wk later). Compared to intact boars, immunocastration reduced ( P 0.05 ) serum concentrations of LH, FSH, testosterone and inhibin B and caused severe testicular atrophy, whereas...
The aim of this work was to study the androgen receptors (AR) expression in pituitary pars distalis (PD) of male viscachas in relation to growth and reproductive cycle. AR were detected by immunocytochemistry and quantified by image analysis. Pituitary glands from fetus, immature, prepubertal, and adult viscachas during their reproductive cycle were used. In the fetal PD, the immunoreactivity (ir) was mainly cytoplasmic. In immature and prepubertal animals, AR-ir was cytoplasmic (ARc-ir) and nuc...
The aims of the present study were to determine whether castration results in quantitative immunohistochemical changes in androgen receptors (AR), LH-immunoreactive (IR) cells and FSH-IR cells, and to analyse the colocalisation of AR and gonadotropins in the pituitary pars distalis (PD) of viscachas. Pituitaries were processed for light and electron microscopy. AR-IR, LH-IR and FSH-IR cells were detected by immunohistochemistry. In morphometric studies, the percentage of AR-IR, LH-IR, FSH-IR, LH...
The experiment was aimed at investigating the relationship between reduced circulating/endogenous testosterone occasioned by orchiectomy and emotional behavior using the open field test. Eighteen male Wistar rats were randomly selected and classified into two groups: orchiectomized and nonorchiectomized. Orchiectomy was carried out by simple sham surgery. After recovery from orchiectomy, plasma testosterone was determined in both groups after which each animal was observed in the open-field for ...
Anabolic steroids are widely used to increase skeletal muscle (SM) mass and improve physical performance. Some dietary supplements also include potent steroid precursors or active steroid analogs such as nandrolone. Our previous study reported the anabolic steroid effects on SM in a castrated guinea pig model with SM measured using a highly quantitative magnetic resonance imaging (MRI) protocol. The aim of the current study was to apply this animal model and in vivo MRI protocol to evaluate the ...
Last. Nancy G. Forger(UMass: University of Massachusetts Amherst)H-Index: 42
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Abstract Naked mole-rats (Heterocephalus glaber) are eusocial rodents that live in large subterranean colonies including a single breeding female and 1–3 breeding males; all other members of the colony, known as subordinates, are reproductively suppressed. We recently found that naked mole-rats lack many of the sex differences in the brain and spinal cord commonly found in other rodents. Instead, neural morphology is influenced by breeding status, such that breeders, regardless of sex, have more...
Last. Joseph R. Vasselli(Mount Sinai St. Luke's and Mount Sinai Roosevelt)H-Index: 12
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This study aimed to develop a quantitative and in vivo magnetic resonance imaging (MRI) approach to investigate the muscle growth effects of anabolic steroids. A protocol of MRI acquisition on a standard clinical 1.5 Tesla scanner and quantitative image analysis was established and employed to measure the individual muscle and organ volumes in the intact and castrated guinea pigs undergoing a 16-week treatment protocol by two well-documented anabolic steroids, testosterone and nandrolone, via im...
Last. Paul Simoens(UGent: Ghent University)H-Index: 27
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The present study aimed to determine the extent to which the androgen receptor (AR) is directly involved in the hormonal modulation of pathological canine aggressive behaviour in the basolateral nuclear group (BNG) of the amygdaloid body. A stereological quantification of AR-positive neurons was performed in the BNGs of normally behaving and aggressive male dogs. The BNG was selected because it is involved in sexual and behavioural activities that are influenced by androgens. In the aggressive d...
Sex and species differences in androgenic regulation of steroid hormone receptor mRNAs were examined in the diencephalon of two species of whiptail lizards: Cnemidophorus inornatus is a sexual species and the direct evolutionary ancestor to Cnemidophorus uniparens, an all-female parthenogenetic species. Lizards were gonadectomized and treated with different doses of either aromatizable testosterone or nonaromatizable dihydrotestosterone. The relative abundances of androgen-, oestrogen-, and prog...
#1Mino D. C. Belle(UCLan: University of Central Lancashire)H-Index: 14
#2Robert W. Lea(UCLan: University of Central Lancashire)H-Index: 31
Abstract Nuclear androgen receptors (ARs) were localized immunocytochemically in the brains of courting and brooding male and female ring doves ( Streptopelia risoria ). AR immunoreactivity (AR-ir) in courting birds was localized in cell nuclei in the telencephalon, diencephalon, and mesencephalon. In the anterior hypothalamus, high density of AR-ir was concentrated in several nuclei including the nucleus lateralis hypothalami, nucleus periventricularis magnocellularis, nucleus preopticus anteri...