Search Results (13)

The use of supraphysiologic testosterone, particularly when alternated with an anti-androgen agent in men with metastatic castration-resistant prostate cancer (CRPC), has demonstrated promising results in clinical trials. As the use of this therapy in clinical practice is more widely adopted, there will be a growing need to understand the mechanisms of resistance. To that end, we independently derived three separate cell models of testosterone-sensitive CRPC. From each CRPC line, high dose testosterone-resistance (HTR) lines were selected. We demonstrated the differential response of the three CRPC lines to a high dose of testosterone in vitro and in vivo. We subsequently demonstrated the resistance of the HTR lines to testosterone and varying responses to testosterone withdrawal in vivo. The heterogeneity in responses to hormonal manipulation is correlated with varying levels of androgen receptor expression within the population. Overall, we show that we have developed three models of HTR that can be used to study the mechanisms of high dose testosterone resistance and identify potential therapeutic targets. Full article

Objective: This study investigated the effects of a supraphysiological dose of testosterone on uterine morphology and the regulation of the leukaemia inhibitory factor (LIF) signalling pathway during endometrial receptivity. Methods: In this study, 30 adult female Sprague–Dawley rats were divided into treatment and control groups. The treatment groups received subcutaneous injections of 1 mg/kg/day of testosterone from gestational day 1 to day 3, either testosterone alone or in combination with inhibitors (anastrozole, finasteride, or both). A control group of six untreated rats was maintained for comparison. Rats were euthanised on the evening of gestational day 4 to examine uterine morphological changes, gene expression and the distribution of proteins associated with the LIF signalling pathway (LIF, LIFR, JAK1 and STAT3) and MUC1 by quantitative polymerase chain reaction (qPCR) and immunohistochemistry (IHC), respectively. Results: The results of this study showed that the thickness of the endometrium and myometrium, as well as the number of glands, markedly decreased in all testosterone-treated rats. In addition, the mRNA levels of LIF, LIFR, JAK1 and STAT3 were significantly downregulated in response to supraphysiological testosterone treatment, while the mRNA of MUC1 was significantly upregulated. The IHC results were consistent with the mRNA data and confirmed the changes in protein distribution in all treatment groups. Conclusions: A supraphysiological dose of testosterone may impair endometrial receptivity through dysregulation of the LIF signalling pathway, potentially affecting fertility. Full article

This study aims to investigate the effect of a supraphysiological dose of testosterone on the levels of sex steroid hormones and the expression and distribution of sex steroid receptors in the uterus during the endometrial receptivity development period. In this study, adult female Sprague–Dawley rats (n = 24) were subcutaneously administered 1 mg/kg/day of testosterone alone or in combination with the inhibitors (finasteride or anastrozole or both) from day 1 to day 3 post-coitus, while a group of six untreated rats served as a control group. The rats were sacrificed on the evening of post-coital day 4 of to measure sex steroid hormone levels by ELISA. Meanwhile, gene expression and protein distribution of sex steroid receptors were analysed by quantitative polymerase chain reaction (qPCR) and immunohistochemistry (IHC), respectively. In this study, treatment with a supraphysiological dose of testosterone led to a significant reduction in oestrogen and progesterone levels compared to the control. The mRNA expression of the androgen receptor increased significantly in all treatment groups, while the mRNA expression of both the progesterone receptor and the oestrogen receptor-α decreased significantly in all treatment groups. The IHC findings of all sex steroid receptors were coherent with all mRNAs involved. This study shows that a supraphysiological dose of testosterone was able to interrupt the short period of the implantation window. This finding could serve as a basis for understanding the role of testosterone in endometrial receptivity in order to develop further therapeutic approaches targeting androgen-mediated disorders of endometrial receptivity. Full article

It has been described in some female mammalian species that postnatal androgenization causes reproductive structural and functional abnormalities. The objective of this study was to describe the clinical, ovulatory and genital effects of postnatal androgens in female dogs. Ten newborn female crossbred puppies were randomly assigned to: testosterone enanthate 18 mg/100 g sc (TE; n = 5) or placebo sc (PL; n = 5). The puppies were physically followed up until puberty when ovulation was tested by serum progesterone. Then, ovariohysterectomies were performed, and genital tracts were grossly and histomorphometrically examined. At puberty, all the females had normal estrous behavior and ovulated without age and body weight differences. All TE puppies presented mild clitoris enlargement. Gross and microscopical ovarian examination did not reveal differences. Conversely, the endometrial area occupied by uterine glands as well as the height of the glandular and luminal epithelium were higher in the TE than in the PL group (<0.01). The height of the endometrium and myometrial thickness did not differ between groups. It was concluded that a supraphysiological postnatal dose of testosterone did not affect ovulatory capacity, nor did it provoke gonadal histological alterations, although it caused an increased area of endometrial glands and a higher uterine epithelium. Full article

Androgen deprivation therapy (ADT) is a primary treatment for advanced prostate cancer (PCa), but resistance often leads to castration-resistant PCa (CRPC). CRPC remains androgen receptor (AR)-dependent, and AR overexpression causes vulnerability to high doses of androgen in CRPC. Bipolar androgen therapy (BAT) refers to the periodic administration of testosterone, resulting in oscillation between supraphysiologic and near-castrate serum testosterone levels. In this study, we evaluated the efficacy of BAT against CRPC in a preclinical setting. To emulate CRPC characteristics, PCa cell lines (LNCaP, VCaP, and 22Rv1) were cultured in phenol red-free RPMI-1640 medium supplemented with 10% dextran-coated charcoal treated FBS (A− cell line). Cell viability, AR, and AR-V7 expression were evaluated using the Cell Counting Kit-8 and Western blotting. In vivo studies involved 12 castrated NOG mice injected with LNCaP/A− cells, treated with testosterone pellets or controls in 2-week cycles. Tumor sizes were measured post a 6-week treatment cycle. Bicalutamide inhibited PCa cell viability but not in the adapted cell lines. Supraphysiologic androgen levels suppressed AR-expressing PCa cell growth in vitro. In vivo, high AR-expressing LNCaP cells proliferated under castrate conditions, while BAT-treated xenografts exhibited significant growth inhibition with low Ki-67 and mitotic indexes and a high cell death index. This study provides preliminary evidence that BAT is effective for the treatment of CRPC through rapid cycling between supraphysiologic and near-castrate serum testosterone levels, inducing an anti-tumor effect. Full article

The salivary glands play a central role in the secretion of saliva, whose composition and volume affect oral and overall health. A lesser-explored dimension encompasses the possible changes in salivary gland proteomes in response to fluctuations in sex hormone levels. This study aimed to examine the effects of chronic exposure to testosterone on salivary gland remodeling, particularly focusing on proteomic adaptations. Therefore, male Wistar rats were implanted with subcutaneous testosterone-releasing devices at 14 weeks of age. Their submandibular glands were histologically and molecularly analyzed 47 weeks later. The results underscored a significant increase in gland mass after testosterone exposure, further supported by histologic evidence of granular duct enlargement. Despite increased circulating sex hormones, there was no detectable shift in the tissue levels of estrogen alpha and androgen receptors. GeLC-MS/MS and subsequent bioinformatics identified 308 proteins in the submandibular glands, 12 of which were modulated by testosterone. Of note was the pronounced upregulation of Klk3 and the downregulation of Klk6 and Klk7 after testosterone exposure. Protein–protein interaction analysis with the androgen receptor suggests that Klk3 is a potential target of androgenic signaling, paralleling previous findings in the prostate. This exploratory analysis sheds light on the response of salivary glands to testosterone exposure, providing proteome-level insights into the associated weight and histological changes. Full article

Background and Objectives: Nandrolone decanoate (ND) is the most widely used among the anabolic androgenic steroids (AAS), synthetic substances derived from testosterone, to improve muscular and health gains associated with exercises. The AAS leads to physical performance enhancement and presents anti-aging properties, but its abuse is associated with several adverse effects. Supraphysiological doses of AAS with or without physical exercise can cause morphological and functional alterations in neuromuscular interactions. This study aims to investigate the effects of ND supraphysiological doses in neuromuscular interactions, focusing on the soleus muscle and its neuromuscular junctions (NMJs) in rats, associated or not with physical exercise. Materials and Methods: Forty male Sprague Dawley rats were divided into four groups: sedentary and exercised groups, with or without ND at the dose of 10 mg/kg/week. The animals were treated for eight weeks, with intramuscular injections, and the soleus muscle was collected for morphological analyses. Results: The supraphysiological doses of ND in the sedentary group caused muscle degeneration, evidenced by splitting fibers, clusters of small fibers, irregular myofibrils, altered sarcomeres, an increase in collagen deposition and in the number of type I muscle fibers (slow-twitch) and central nuclei, as well as a decrease in fibers with peripheral nuclei. On the other hand, in the ND exercise group, there was an increase in the NMJs diameter with scattering of its acetylcholine receptors, although no major morphological changes were found in the skeletal muscle. Thus, the alterations caused by ND in sedentary rats were partially reversed by physical exercise. Conclusions: The supraphysiological ND exposure in the sedentary rats promoted an increase in muscle oxidative pattern and adverse morphological alterations in skeletal muscle, resulting from damage or post-injury regeneration. In the ND-exercised rats, no major morphological changes were found. Thus, the physical exercise partially reversed the alterations caused by ND in sedentary rats. Full article

Androgen deprivation therapy (ADT) remains the cornerstone of advanced prostate cancer treatment. However, the progression towards castration-resistant prostate cancer is inevitable, as the cancer cells reactivate androgen receptor signaling and adapt to the castrate state through autoregulation of the androgen receptor. Additionally, the upfront use of novel hormonal agents such as enzalutamide and abiraterone acetate may result in long-term toxicities and may trigger the selection of AR-independent cells through “Darwinian” treatment-induced pressure. Therefore, it is crucial to develop new strategies to overcome these challenges. Bipolar androgen therapy (BAT) is one such approach that has been devised based on studies demonstrating the paradoxical inhibitory effects of supraphysiologic testosterone on prostate cancer growth, achieved through a variety of mechanisms acting in concert. BAT involves rapidly alternating testosterone levels between supraphysiological and near-castrate levels over a period of a month, achieved through monthly intramuscular injections of testosterone plus concurrent ADT. BAT is effective and well-tolerated, improving quality of life and potentially re-sensitizing patients to previous hormonal therapies after progression. By exploring the mechanisms and clinical evidence for BAT, this review seeks to shed light on its potential as a promising new approach to prostate cancer treatment. Full article

Since the Nobel Prize-winning work of Huggins, androgen ablation has been a mainstay for treatment of recurrent prostate cancer. While initially effective for most patients, prostate cancers inevitably develop the ability to survive, grow, and metastasize further, despite ongoing androgen suppression. Here, we briefly review key preclinical studies over decades and include illustrative examples from our own laboratories that suggest prostate cancer cells titrate androgen signaling to optimize growth. Such laboratory-based studies argue that adaptations that allow growth in a low-androgen environment render prostate cancer sensitive to restoration of androgens, especially at supraphysiologic doses. Based on preclinical data as well as clinical observations, trials employing high-dose testosterone (HDT) therapy have now been conducted. These trials suggest a clinical benefit in cancer response and quality of life in a subset of castration-resistant prostate cancer patients. Laboratory studies also suggest that HDT may yet be optimized further to improve efficacy or durability of response. However, laboratory observations suggest that the cancer will inevitably adapt to HDT, and, as with prior androgen deprivation, disease progression follows. Nonetheless, the adaptations made to render tumors resistant to hormonal manipulations may reveal vulnerabilities that can be exploited to prolong survival and provide other clinical benefits. Full article

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

The objective of this study was to determine the effect of long-term (48 days), per os administration of specific zearalenone (ZEN) doses (20 and 40 μg ZEN/kg BW in experimental groups EI and EII, which were equivalent to 200% and 400% of the upper range limit of the no-observed-adverse-effect-level (NOAEL), respectively) on the bioavailability of ZEN and the rate of changes in estradiol and testosterone concentrations in the peripheral blood of pre-pubertal gilts. ZEN and α-ZEL levels were similar until day 28. After day 28, α-ZEL concentrations increased significantly in group EI, whereas a significant rise in ZEN levels was noted in group EII. The presence of estradiol in peripheral blood plasma was not observed until day 20 of the experiment. Spontaneous secretion of estradiol was minimal, and it was determined at very low levels of up to 10 pg/mL in EI and EII groups. Testosterone concentrations ranged from 4 to 9 ng/mL in all groups. A decrease in the concentrations of both analyzed hormones was reported in the last stage of the experiment. The results of the experiment indicate that: (i) The bioavailability of ZEN in peripheral blood has low diagnostic value, (ii) exposure to low doses of ZEN induces minor changes in the concentrations of the analyzed hormones, which could lead to situational supraphysiological hormone levels and changes in endogenous hormonal balance. Full article

Background and Objectives: Anabolic androgenic steroids (AASs) are a complex group of molecules that include both steroidal androgens and synthetic compounds, derived from testosterone. AASs are commonly used to support pharmacological therapy in cases of primary or secondary hypogonadism, major burns, and neoplastic cachexia. Their prolonged and supra-physiological consumption can provoke several adverse effects on various organs and systems. Among these, the physiopathological mechanisms that induce neuropsychiatric disorders related to AAS abuse are poorly known. For this reason, the proposed review aims to retrace the pathway of action of testosterone to focus on the effects on the central nervous system and specifically highlight the effects of AASs on neuropsychiatric and behavioral functions, as well as on lifestyle. Materials and Methods: This review was conducted using PubMed and Google Scholar databases. On these database websites, we searched for articles from 1 January 1980 to March 2019 using the key terms: “AAS,” “Anabolic Androgenic Steroids,” “brain,” and “neurology.” Results: The use of AASs through self-administration yields circulating androgens levels, inducing neuron apoptosis, which is linked to thinner cortex and, in general, less cortical volume. The same alterations affect the putamen. These differences were more evident when correlated with longer use. From a functional point of view, prolonged AAS consumption seemed to be related to lower connectivity between amygdala and frontal, striatal, limbic, hippocampal and visual cortical areas. On the other hand, AAS use seems to negatively condition the positive effects of the sport exercise, reducing its important anti-apoptotic and pro-proliferative functions on the hippocampus, implicated in anxiolytic control. Conclusion: This review clarifies the major aspects of the side effects related to AAS use/abuse highlighting the complex mechanisms on neuropsychiatric and cognitive pathological alterations and also the emotional and behavioral dysfunctions. Full article

Since Huggins defined the androgen-sensitive nature of prostate cancer (PCa), suppression of systemic testosterone (T) has remained the most effective initial therapy for advanced disease although progression inevitably occurs. From the inception of clinical efforts to suppress androgen receptor (AR) signaling by reducing AR ligands, it was also recognized that administration of T in men with castration-resistant prostate cancer (CRPC) could result in substantial clinical responses. Data from preclinical models have reproducibly shown biphasic responses to T administration, with proliferation at low androgen concentrations and growth inhibition at supraphysiological T concentrations. Many questions regarding the biphasic response of PCa to androgen treatment remain, primarily regarding the mechanisms driving these responses and how best to exploit the biphasic phenomenon clinically. Here we review the preclinical and clinical data on high dose androgen growth repression and discuss cellular pathways and mechanisms likely to be involved in mediating this response. Although meaningful clinical responses have now been observed in men with PCa treated with high dose T, not all men respond, leading to questions regarding which tumor characteristics promote response or resistance, and highlighting the need for studies designed to determine the molecular mechanism(s) driving these responses and identify predictive biomarkers. Full article