SEARCH · Search PubMed

Results for “testosterone secretion”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,045 records · Page 58Linked to original sources

PubMed2004

Development of the caput epididymidis studied by expressed proteins (a glutamate transporter, a lipocalin and beta-galactosidase) in the c-ros knockout and wild-type mice with prepubertally ligated efferent ducts.

Expression of a glutamate transporter (EAAC1), a lipocalin (MEP17) and beta-galactosidase (beta-Gal) in histological sections was used to monitor post-natal development of the murine epididymis. Three epithelia in the adult caput of wild-type mice were distinguished: I, the initial segment; II, the proximal caput; and III, the distal caput. The regions in which epithelia I, II and III were situated were called regions I, II and III, respectively. Regions I, II and III developed from a precursor epithelium present on day 14; from day 16, a presumptive region I epithelium was evident and, by day 21, epithelia characteristic of future regions II and III appeared. The relationship between the c-ros gene and the initial segment was studied by investigating the development of the caput epididymidis in transgenic homozygous c-ros knockout (-/-) mice that lack the initial segment, heterozygous (+/-) males and wild-type males in which the efferent ducts had been ligated prepubertally so that the initial segment failed to develop. In mice with prepubertally ligated efferent ducts, regions II and III developed normally but region I was missing in the adult and expression of c-ros was partially decreased. In (-/-) mice, the precursor epithelium was present, differentiation of epithelium II was delayed until day 32 and epithelium I never developed. Thus, caput region I develops before c-ros expression, high testosterone secretion and differentiation of regions II and III but not if the organ is deprived of the oncogene c-ros or testicular exocrine secretions. The caput of the knockout male lacks solely the initial segment so that the efferent ducts are in continuity with the post-initial segment, proximal caput region. The ligand for c-ros may be present in testicular fluid and both ligand and receptor may be necessary for differentiation of epithelia I and II.

Aging↗

PubMed1995

Rotational dynamics of luteinizing hormone receptors and MHC class I antigens on murine Leydig cells.

We have examined the molecular motions of luteinizing hormone (LH) receptor and the Major Histocompatibility Complex Class I antigen on murine Leydig cells. Using time-resolved phosphorescence anisotropy methods, erythrosin (ErITC)-derivatized ovine luteinizing hormone (oLH) bound to the LH receptor appears rotationally mobile with rotational correlation times of 19.6 +/- 1.3 microseconds, 13.3 +/- 2.4 microseconds, 9.5 +/- 0.7 microseconds and 4.7 +/- 0.5 microseconds at 4 degrees C, 15 degrees C, 25 degrees C and 37 degrees C, respectively. Rotational correlation times for human chorionic gonadotropin (hCG)-occupied LH receptors were similar to those of the ErITC-oLH occupied receptor at each temperature. In addition, both oLH- and hCG-occupied LH receptors were laterally mobile in fluorescence photobleaching recovery experiments with diffusion coefficients at 29 degrees C of (5.8 +/- 0.9) x 10(-10) cm2 s-1 and (2.9 +/- 0.4) x 10(-10) cm2 s-1, respectively. We also measured the rotational correlation time of Class I antigen on murine Leydig cells using ErITC-derivatized 34-12-2S, an anti-Class I monoclonal antibody. Because there was no decay of the anisotropy function at 4 degrees C, 15 degrees C, 25 degrees C or 37 degrees C in the absence of oLH or following preincubation of Leydig cells with 1 nM oLH, it appears that Class I is rotationally immobile on the 1 ms timescale of our experiments. This result is consistent with the presence of Class I antigen in large molecular weight structures and may be the result of Class I self-aggregation. Further, treatment of cells with anti-Class I antibody had no effect on either basal or oLH-stimulated testosterone secretion. Thus, it appears that this anti-Class I antibody is not LH-mimetic on murine Leydig cells.

Animals↗

PubMed1983

Steroid secretion by the prepubertal human testis.

It has been demonstrated that the human testis secretes testosterone and, to a smaller extent and less constantly, also androstenedione. Testosterone, progesterone, 17 alpha-hydroxyprogesterone and 20 alpha-dihydroprogesterone have been measured in the spermatic and peripheral venous blood of prepubertal boys undergoing surgery for undescended testis or inguinal hernia repair. The spermatic plasma levels of testosterone and progesterone were significantly higher than peripheral levels. A significant spermatic-peripheral gradient was not found for 17 alpha-hydroxyprogesterone and 20 alpha-dihydroprogesterone. These studies demonstrate that the secretory pattern of the human prepubertal testis is different from that of the adults.

Androgens↗

PubMed1987

Effect of GABA and benzodiazepines on testicular androgen production.

We have evaluated the effect of Ro5-4864, a selective probe to label peripheral type benzodiazepine receptor, on "in vitro" testicular androgen production. Decapsulated testes from adult rats showed a significant increase in the basal and hCG-stimulated testosterone secretion into the medium in response to 10(-5) M, 10(-6) M, and 10(-7) M Ro5-4864. In addition, we have studied the changes in testicular GABA content at three different ages and we found its highest concentration at 31 days of age. When we evaluated the effect of GABA on "in vitro" androgen production at different stages of gonadal maturation we observed that the highest concentration of GABA (10(-6) M) was able to modify the basal and hCG-stimulated androgen production from adult (60 days) and pubertal (45 days) testes. In addition, when prepubertal testes (31 days) were incubated under basal conditions, 10(-6) M GABA induced a significant increment of androstanediol production, while the stimulatory effect of hCG was reduced in the presence of the same GABA concentration. The present results suggest that GABA plays a physiological role in the regulation of rat testicular androgen production depending on the stage of sexual maturation.

Age Factors↗

PubMed1989

Effect of melatonin on steroid production by rat adrenals under in vitro superfusion conditions.

In vitro superfusion of adrenals from male and female Wistar rats resulted in a gradual decline of the corticosterone content in the samples collected for a period of 80 minutes. ACTH administration either in the beginning or in the end of the perfusion period led to a marked increase in the level of this steroid. Contrary to this, progesterone content in the collected perfusates was constant throughout the experiments and was not influenced by ACTH. The quantities of testosterone secreted under these conditions were below the sensitivity of the assay. Perfusion with melatonin (200 pg/ml) did not affect corticosterone secretion, but resulted in a significant increase of the progesterone content in the recovered fractions. This effect was immediate and was followed by a decline in the progesterone concentration, observed during melatonin perfusion.

Adrenal Glands↗

PubMed1991

Müllerian inhibiting substance blocks epidermal growth factor receptor phosphorylation in fetal rat lung membranes.

Neonatal males develop respiratory distress syndrome more frequently than females for unknown reasons. The fetal testis secretes testosterone and müllerian inhibiting substance (MIS); MIS has been shown to inhibit fetal lung maturation in vitro and in vivo and to block phosphorylation of epidermal growth factor (EGF) receptors in A431 cells. We hypothesized that MIS would also inhibit membrane phosphorylation of EGF receptors in fetal lung, and that ultrastructural study of MIS-exposed lung might complement the biochemical data by assessing the effect of MIS on tissue morphology. Lung membranes were prepared from 19.5-day fetal rats and phosphorylation assays performed with 3 to 4 micrograms of membrane protein, with or without EGF (26 nmol/L), 0.025 mCi AT32P (0.136 mumol/L), and either recombinant human MIS (rhMIS, 30 pmol) from media of Chinese hamster ovary (CHO) cells, rhMIS dialysis buffer, or wild-type CHO media. The 170,000 molecular weight EGF receptor, visualized by autoradiography of polyacrylamide gels, was phosphorylated in both female and male membranes. rhMIS, when added to EGF-stimulated membranes, caused significant inhibition of EGF receptor phosphorylation (females: 32.42% +/- 11.5%; males: 32.3% +/- 19.1%, P less than 0.001; rhMIS-treated v EGF-stimulated state, P = NS, male v female, Cerenkov counting). Electron microscopy (EM) of rhMIS-exposed lung showed decreased lamellar bodies (LB) in both male alveolar spaces and female parenchyma, and, unexpectedly, increased numbers in female alveoli. Immunoabsorption experiments using coincubation of rhMIS with anti-rhMIS IgG polyclonal antibodies or equiprotein normal IgG demonstrated MIS antibody-specific reversal of rhMIS activity in membrane phosphorylation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1986

Medial preoptic-anterior hypothalamic lesions in prepubertal male cats: effects on juvenile and adult sociosexual behaviors.

Bilateral lesions of the medial preoptic-anterior hypothalamic (MP-AH) area were made in prepubertal male cats at 6-8 weeks of age. All subjects were subsequently reared in groups containing male and female peers, until the last phase of the juvenile period when an adult estrous female was inserted in these social groups. In spite of such optimal conditions for the practice of sociosexual behaviors during development, no sparing of adult male copulatory behavior was observed in these MP-AH animals during testing in adulthood. This finding, while consistent with earlier work on dogs, contrasts with the results obtained in prepubertally lesioned rats. Urine spraying, another sexually dimorphic behavior which is eliminated by MP-AH lesions in adult cats, was spared by prepubertal lesion placement. Heterotypical sexual behavior was not enhanced by prepubertal MP-AH lesion placement, as it is with postpubertal placement. In the present study, therefore, different behavioral systems influenced by the MP-AH area showed varying degrees of plasticity. As found in dogs, prepubertal MP-AH lesions enhanced and accelerated testosterone secretion in cats.

Animals↗

PubMed1992

Serum testosterone concentration in response to exogenous GnRH does not predict service rates or pregnancy rates by yearling, performance tested, crossbred bulls.

Ten bulls with a scrotal circumference of less than 30 cm at the end of growth performance testing, and 10 cohorts of the same age, size and breed type with a scrotal circumference greater than 30 cm were used to evaluate if testosterone response following GnRH administration could be used to test for fertility, for semen quality, and for specific pathologic testicular parenchymal changes. Serum testosterone concentrations were determined immediately before and 2 to 3 hours following intramuscular injection of 250 ug GnRH. Bulls were examined for breeding soundness, then fertility was tested in a breeding trial; testicular histology was assessed by determining the percentage of cross-sections of seminiferous tubules with no spermatocytes. The mean (+/-SEM) post-GnRH serum testosterone concentration for all bulls was 11.71 (+/-0.64) ng/ml. In order to examine for an association, the GnRH response was classified as above or below the mean for resultant serum testosterone concentration. The GnRH response classification was not related to the scrotal circumference, percentage of tubules devoid of spermatocytes, or percentage of progressively motile spermatozoa (P>0.10). The percentage of morphologically normal spermatozoa was significantly higher (P<0.05) in the bulls with a higher than mean testosterone secretion in response to GnRH injection. In the breeding trial, the percentage of heifers bred and the percentage of heifers pregnant (60 days post breeding) were not significantly different (P>0.10) between the 2 classifications of GnRH response. The GnRH response test was related to the percentage of morphologically normal spermatozoa but did not predict fertility of yearling bulls in this study.

Journal Article↗

PubMed1979

The effect of induced hyperprolactinaemia on Leydig cell function and LH-induced loss of LH-receptors in the rat testis.

Anterior pituitary glands were transplanted beneath the kidney capsule of intact, adult male rats to induce hyperprolactinaemia. This resulted in reduced serum levels of LH and FSH and increased adrenal weight. In pituitary-transplanted rats, testicular hCG-receptor binding was increased by 55 to 175%, whilst the capacity of the testis to secrete testosterone in vitro was greatly reduced. Injection of ovine LH into control and pituitary-transplanted rats resulted in similar percentage reductions in hCG-receptor binding in the two groups. This treatment impaired the in vitro steroidogenic responsiveness of testes from control rats at 24 h after injection, but had no major effect on the already-impaired, steroidogenic responsiveness of testes from pituitary-transplanted rats. Although induction of hyperprolactinaemia resulted in marked changes in Leydig cell function, these alterations were possibly due to the chronically reduced serum gonadotrophin levels in hyperprolactinaemic rats as well as a direct effect of prolactin on the Leydig cell.

Animals↗

PubMed1995

Gender and the use of neuroleptics in schizophrenia. Further testing of the oestrogen hypothesis.

According to the oestrogen hypothesis, the lower need for neuroleptic drugs in female schizophrenics is caused by the antidopaminergic effect of oestrogens. Due to the decreased oestrogen production during the menopause, this 'neuroleptic' effect is lost and the need for neuroleptic drugs increases in female schizophrenics. This hypothesis was tested by studying a sample of 1097 schizophrenic patients (DSM-III-R), who were discharged from hospital and followed for three years. Prescribed daily doses of neuroleptic drugs were recorded and converted to chlorpromazine equivalents. Males had higher daily doses of neuroleptics than females; this gender difference, however, was only significant in middle-aged groups. Daily doses were also associated with age at the onset of illness, duration of illness and clinical status. Results did not support the oestrogen hypothesis: In females, there was no consistent increase in daily doses of neuroleptics after menopause age. Results are discussed from the viewpoint of testosterone secretion, body weight and smoking habits, which are gender-bound and thus can, at least in part, explain gender differences in the use of neuroleptic drugs in schizophrenic patients. It is pointed out that the age at the onset of illness and the duration of illness should be taken into account when the effects of gender and age on the need for neuroleptics are studied.

Adolescent↗

PubMed1990

Antiandrogens: clinical applications.

Antiandrogens, preventing androgen action at target tissue level, are used in the treatment of various androgen-dependent diseases. Pharmacologically these substances have either a steroidal structure, like cyproterone acetate (CPA) and spironolactone (SPL), or a non-steroidal structure, like flutamide (FLU). In women with hyperandrogenism (PCO syndrome, idiopathic hirsutism, acne), clinical benefit may be obtained with CPA, which also displays a progestational activity and an antigonadotropic effect. CPA (25-50 mg/day) is used in combination with ethinyl-estradiol (EE) (20-30 micrograms/day) in reversed sequential regimen. SPL, less effective than CPA may be employed in moderate hirsutism and acne at dosages of 100-200 mg/day. During SPL treatment menstrual irregularities are frequent: in this case an association with oral contraceptives is indicated. SPL + bromocriptine (2.5-5 mg/day) has been experienced with success in PCO syndrome. The pure antiandrogen FLU, inducing progressive increase in LH and testosterone secretion, may be used only in combination with oral contraceptives. In men antiandrogens have been tested in BPH and prostatic carcinoma. In BPH the decrease in nuclear receptors and DHT nuclear content during CPA or FLU may represent the rational base of the medical treatment. An improvement in urinary obstructive manifestation has been observed with CPA alone or associated with tamoxifen (100 mg + 100 mg day). In advanced prostatic carcinoma antiandrogens represent a good alternative to estrogen therapy with less side effects and in combination with surgical or medical castration (LH-RH analogues) achieve a complete androgen blockade. An increase in the percentage of remissions and survival has been reported.

Acne Vulgaris↗

PubMed1991

Regulation by growth factors of Leydig cell differentiated functions.

In this paper the effects of growth factors on the differentiated function of pig Leydig cells and other steroidogenic cells are reviewed. Two types of action have been observed, i.e. positive or negative acute effects on testosterone secretion, and long-term trophic effects of hCG receptor and responsiveness to hCG. Among the growth factors, insulin-like growth factor I (IGF-I) and transforming growth factor beta (TGF beta-1) are of particular interest. IGF-I is required for the maintenance and probably the expression of differentiated functions of several steroidogenic cells, including the Leydig cells. TGF beta-1 has effects opposite to IGF-I on Leydig cell functions. When considering effects of growth factors on Leydig cells, caution should be taken in extrapolating results obtained in one species to another.

Animals↗

PubMed1996

In vitro studies of the subtypes of endothelin (ET) receptors present in the rat testis, and of their involvement in the secretory response of Leydig cells to ET-1.

The distribution of the endothelin (ET)-receptor subtypes ET(A) and ET(B) in the rat testis and their involvement in the secretory response of Leydig cells to ET-1 have been investigated by the use of specific ligands. Autoradiography showed that [125I]ET-1 binding was intense in the interstitial area of the testis, containing Leydig cells, and virtually absent in the walls of seminiferous tubules. Labelling was almost completely displaced by BQ-123, a selective ETA receptor antagonist, while sarafotoxin-6C and BQ-788, two specific ET(B) ligands, were ineffective. ET-1 concentration-dependently enhanced testosterone secretion of dispersed rat Leydig cells, and the response was suppressed by BQ-123, but not by BQ-788. Both antagonists per se did not affect either basal and hCG stimulated secretion of Leydig cells. Taken together our findings indicate that rat Leydig cells are mainly, provided with ETA, and that this ET-receptor subtype mediates their secretory response to ET-1.

Animals↗

PubMed2005

Steroid-dependent plasticity in the medial amygdala.

Behavioral sex differences have traditionally been thought to arise from gonadal steroids during a neonatal sensitive period. However, it is possible to sex-reverse certain behaviors by reversing the levels of circulating androgen in adult males and females. These results suggest that the sexually dimorphic substrates of sex behavior are subject to a high degree of plasticity, even in adulthood. I have found that circulating androgen exerts a trophic effect on the Nissl-stained morphology of an important nucleus in the control of sex behavior, namely, the posterodorsal subnucleus of the medial amygdala. First, sex-reversing the level of circulating androgen reversed the sex difference in soma size and regional volume of the posterodorsal subnucleus of the medial amygdala in adult rats. Interestingly, activation of both androgen and estrogen receptors was necessary for the post-castration maintenance of a masculine phenotype in terms of posterodorsal subnucleus of the medial amygdala cell size, whereas only estrogen receptor activity was necessary to maintain a masculine posterodorsal subnucleus of the medial amygdala volume. Then, we showed that seasonal variation in androgen was correlated with morphologic plasticity in the posterodorsal subnucleus of the medial amygdala of the Siberian hamster. However, if the experimental males were housed with females, their posterodorsal subnucleus of the medial amygdalas failed to regress in response to winter-like short daylengths. Furthermore, when male hamsters were castrated and treated with testosterone, the posterodorsal subnucleus of the medial amygdala responded to the hormone only if the animals were in summer-like photoperiods. Overall, these findings indicate that circulating androgens are critical for the maintenance of greater posterodorsal subnucleus of the medial amygdala regional volumes and soma sizes, and that environmental variables can regulate testosterone secretion and responsiveness.

Amygdala↗

PubMed2006

Neonatal genistein or bisphenol-A exposure alters sexual differentiation of the AVPV.

There is growing concern that naturally occurring and chemically manufactured endocrine-active compounds (EACs) may disrupt hormone-dependent events during central nervous system development. We examined whether postnatal exposure to the phytoestrogen genistein (GEN) or the plastics component bisphenol-A (BIS) affected sexual differentiation of the anteroventral periventricular nucleus of the hypothalamus (AVPV) in rats. The AVPV is sexually differentiated in rodents. The female AVPV is larger than the male AVPV and contains a higher number of cells expressing tyrosine hydroxylase (TH). Sexual differentiation of the AVPV results from exposure of the male nervous system to estrogen aromatized from testicular testosterone secreted in the first few days after birth. Thus, we hypothesized that exposure to EACs during this critical period could alter the sexually dimorphic expression of TH and the overall expression of estrogen receptor alpha (ERalpha) in the AVPV. Animals were given 4 subcutaneous injections of sesame oil (control), 50 microg 17beta-estradiol (E2), 250 microg GEN, or 250 microg BIS at 12-h intervals over postnatal days (PND) 1 and 2 and sacrificed on PND 19. E2 treatment masculinized TH immunoreactivity (TH-ir) in the female AVPV while exposure to GEN or BIS demasculinized TH-ir in the male AVPV. In addition, we identified a population of neurons co-expressing TH and ERalpha located primarily in the medial region of the AVPV. Normally, females have nearly three times as many double-labeled cells as males, but their numbers were defeminized by E2, GEN or BIS treatment. These results suggest that acute exposure to EACs during a critical developmental period alters AVPV development.

Animals↗

PubMedDate not supplied

Are XX and XY brain cells intrinsically different?

In mammals and birds, the sex of the gonads is determined by genes on the sex chromosomes. For example, the mammalian Y-linked gene Sry causes testis differentiation. The testes then secrete testosterone, which acts on the brain (often after conversion to estradiol) to cause masculine patterns of development. If this were the only reason for sex differences in neural development, then XX and XY brain cells would have to be deemed otherwise equivalent. This equivalence is doubtful because of recent experimental results demonstrating that some XX and XY tissues, including the brain, are sexually dimorphic even when they develop in a similar endocrine environment. Although X and Y genes probably influence brain phenotype in a sex-specific manner, much more information is needed to identify the magnitude and character of these effects.

Animals↗

PubMed2005

A masculinized skeletomusculature is not necessary for male-typical patterns of food-protective movement.

Although sexual dimorphism in movement has been documented in rodents, the extent to which it relates to dimorphic neural control versus dimorphic body size/structure is unclear. We have shown previously that male and female rats are sexually dimorphic with regards to the lateral movements and hindpaw stepping they use to protect a food item. We addressed the question of whether this sexual dimorphism is due to sex differences in peripheral skeletomusculature or in the CNS by examining the movement composition used during dodging to protect a food item by tfm-affected males and their wild-type male (WTM) and female (WTF) controls. The tfm-affected male, while genetically male, develops internal testes that secrete testosterone, but is phenotypically female due to a failure of androgen receptor-mediated masculinization of the periphery. Masculinization of the CNS of tfm-affected males, however, is primarily accomplished by the actions of testosterone's aromatized metabolite estradiol acting via estrogen receptors. Thus the tfm-affected male provides an assay by which the relative contributions of the skeletomusculature or CNS to sex differences in movement organization can be addressed. We found that female wild-type animals were significantly different from both the tfm-affected and wild-type males. There were no significant differences in dodge patterns used by tfm-affected males and their wild-type male controls. This study provides evidence that the sex differences in dodging patterns are mediated primarily by CNS mechanisms and are not primarily dependent on a male- or female-typical skeletomusculature.

Androgen-Insensitivity Syndrome↗

PubMed2002

Effects of follicle-stimulating hormone (FSH) and human chorionic gonadotropin in individuals with an inactivating mutation of the FSH receptor.

OBJECTIVE: To study the gonadal steroid responses to FSH and hCG in individuals with the inherited Finnish-type inactivating Ala189Val mutation of the FSH receptor gene. DESIGN: Prospective clinical and descriptive study. SETTING: University hospital. PATIENT(S): Two women and one man homozygous for the Ala189Val mutation of the FSH receptor gene, and ovarian biopsies from four affected and four healthy women, and four normal fetuses. INTERVENTION(S): Individuals were treated with increasing doses of recombinant FSH (300 IU/day start, 900 IU/day final) and/or a single dose of hCG (5000 IU). Ovarian biopsies were used in immunohistochemical analyses for detection of aromatase cytochrome P450 and transcription factor GATA-4. In situ 3'-end labeling analyses were used for detection of apoptosis. MAIN OUTCOME MEASURE(S): Measurements of serum concentrations of follicle-stimulating hormone, leuteinizing hormone, inhibin A and B, estradiol, testosterone (T), androstenedione, and prolactin, immunostaining for ovarian aromatase, GATA-4, and apoptosis. RESULT(S): Administration of FSH had no effect on production of the steroids. Similarly, human chorionic gonadotropin (hCG) treatment, alone or after FSH administration, failed to raise serum steroid concentrations. Ovarian apoptosis was absent, and the expression of transcription factor GATA-4 and aromatase was negligible in the ovarian biopsies from Ala189Val homozygous individuals. CONCLUSION(S): The Ala189Val mutation of the FSH receptor gene results in a complete block of FSH action in vivo. Furthermore, the failure of hCG to increase both ovarian estradiol and testosterone secretion emphasizes the possible contribution of FSH in regulating ovarian androgen synthesis, and supports the concept that both gonadotropins are necessary for appropriate ovarian steroidogenesis in humans.

Adult↗