Serum Testosterone Levels In Mice Research Articles

α-Tocotrienol in rice bran enhances steroidogenesis in mouse Leydig cell via increased gene expression of steroidogenic acute regulatory protein and induction of its mitochondrial translocation.

Rice is a staple food in the Asian region and one of the world's major energy sources. Testosterone is a steroid hormone that maintains physical, sexual, and cognitive ability, and its decline causes health problems like late-onset hypogonadism. Evaluation of various grain extracts showed rice bran to stimulate testosterone secretion from Leydig model cells. α-Tocotrienol was found as a bioactive compound in rice bran, and mechanistic analysis showed the stimulation of steroid hormone synthesis through enhanced gene expression of steroidogenic acute regulatory protein as well as inducing mitochondrial localization of the protein. Preliminary study showed an increasing trend in serum testosterone levels in mice by oral intake of α-tocotrienol. These results suggest that α-tocotrienol intake may be effective in preventing symptoms caused by low testosterone levels.

Amylin regulates testosterone levels via steroidogenesis-related enzymes in the central nervous system of male mice

Amylin is a peripheral satiation signal polypeptide co-secreted with insulin by pancreatic β-cells in response to nutrient ingestion. Amylin participates in the eating-inhibitory effect and regulates energy metabolism by acting on the central nervous system (CNS). However, the role of amylin in regulating the biosynthesis of steroid hormones, such as testosterone, through the hypothalamic-pituitary-gonadal axis (HPG) remains unexplored. However, only limited evidence is available on the involvement of amylin in steroid synthesis, we hypothesize that amylin regulates testosterone levels via steroidogenesis-related enzymes in the CNS. In this study, we elucidated the effect of intraperitoneal injection of amylin on the protein expression of steroidogenesis-related enzymes, including 3β-hydroxysteroid dehydrogenase (3β-HSD), cytochrome P450 17A1 (CYP17A1), and steroidogenic acute regulatory protein (StAR), and phospho-extracellular signal-regulated kinase (pERK). Additionally, the effect of amylin on testosterone levels in male mice was examined. Our results suggested that 3β-HSD and CYP17A1 neurons were widely expressed in the CNS of male mice, whereas StAR neurons were mainly expressed in the zona incerta (ZI) and locus coeruleus (LC) regions. Intraperitoneal injection of amylin significantly reduced (p < 0.01) the expression of 3β-HSD, CYP17A1, and StAR in ZI and other areas near the third ventricle (3 V) but increased (p < 0.01) pERK expression, brain testosterone levels, serum FSH, serum LH, and decreased (p < 0.01) serum testosterone levels in mice. In conclusion, amylin regulates testosterone levels via steroidogenesis-related enzymes in the central nervous system of male mice.

Microcystin-leucine arginine induced the apoptosis of GnRH neurons by activating the endoplasmic reticulum stress resulting in a decrease of serum testosterone level in mice

Microcystin-leucine arginine (MC-LR) is a kind of toxin produced by cyanobacterial, resulting in decrease of testosterone levels in serum and leading to impaired spermatogenesis. Gonadotropin-releasing hormone (GnRH) neurons play crucial roles in the regulation of testosterone release. Meanwhile, it has been demonstrated that MC-LR is capable of entering the GnRH neurons and inducing apoptosis. Nevertheless, the molecular mechanism of MC-LR induced apoptosis of GnRH neurons remains elusive. In present study, we found that MC-LR inhibited the cell viability of GT1–7 cells. In addition, we discovered apoptosis of GnRH neurons and GT1–7 cells treated with MC-LR. And increased intracellular ROS production and the release of intracellular Ca2+ were all observed following exposure to MC-LR. Furthermore, we also found the endoplasmic reticulum stress (ERs) and autophagy were activated by MC-LR. Additionally, pretreatment of the ERs inhibitor (4-Phenyl butyric acid) reduced the apoptotic rate of GT1–7 cells comparing with MC-LR exposure alone. Comparing with MC-LR treatment alone, apoptotic cell death was increased by pretreatment of GT1–7 cells with an autophagy inhibitor (3-methyladenine). Together, our data implicated that the treatment of MC-LR induced the apoptosis of GnRH neurons by activating the ERs resulting in a decrease of serum testosterone level in mice. Autophagy is a protective cellular process which was activated by ER stress and thus protected cells from apoptosis upon MC-LR exposure.

Spatial arrangement of testicular cells disrupted by transient scrotal hyperthermia and subsequent impairment of spermatogenesis.

The spermatogenesis is temperature-dependent and heat stress have destructive effects on spermatogenesis and reduces sperm quality. Sixteen adult mice were allocated to two groups: hyperthermia and control groups. Scrotal hyperthermia was induced by water bath with 43°C for 30min. Then, the spermatozoon was isolated through the tail region of epididymis for sperm parameters analysis. The testicular tissues were taken for stereological studies, hormonal assay, TUNEL assay and molecular studies. We found a marked decrease in sperm parameters and serum testosterone level in mice induced by scrotal hyperthermia as well as stereological analysis indicated a significant reduction in testicular cells and changes in the spatial arrangement of testicular cells in the scrotal hyperthermia groups compared to the control groups. Moreover, the TUNEL assay results showed that apoptotic cells were enhanced significantly in the group of scrotal hyperthermia compared to the control groups. Furthermore, scrotal hyperthermia caused a reduction in the expression of retinoic acid 8 (STRA8), c-kit and proliferating cell nuclear antigen (PCNA) genes in the scrotal hyperthermia groups compared to the control. According to results, induction of transient scrotal hyperthermia leads to a fluctuation in the spatial arrangement of testicular cells, which finally influences the normal function of spermatogenesis.

A novel role for zinc transporter 8 in the facilitation of zinc accumulation and regulation of testosterone synthesis in Leydig cells of human and mouse testicles

ObjectiveZinc is intimately involved in testosterone production. Zinc transporter 8 (ZnT8) is found to be localized in insulin secretory granules as a β-cell specific Zn transporter. The effect of ZnT8 and related zinc accumulation in steroidogenesis, however, is still unknown. The present study aimed to explore whether ZnT8 plays a role in the facilitation of zinc accumulation and regulation of testosterone synthesis in testicles. MethodsLeydig cells were isolated from the testicles of human, CD-1 suckling and ZnT8-KO mice. Zn accumulation in mitochondria was induced by hCG stimulation. Transfection of hZnT8-EGFP and RNA interfere of mZnT8 were done in MLTC-1 cells. ZnT8 expression and its co-localization with steroidogenic acute regulatory (StAR) protein were analyzed with RT-PCR, Western blot and dual-fluorescent staining protocols. Serum testosterone levels in mice were determined with chemiluminescent enzyme immunoassay. ResultsZnT8 was found to be presented in Leydig cells and up-regulated in suckling mouse Leydig cells and MLTC-1 cells after hCG administration, by which zinc accumulation occurred in mitochondria. ZnT8 gene silencing or knockout inhibited stimulated progesterone and testosterone production, reduced stimulated zinc accumulation and down-regulated phosphorylated steroidogenic acute regulatory (StAR) expression in Leydig cells. Furthermore, an inhibitor (H89) of PKA blocked hCG-stimulated progesterone caused by ZnT8 over-expression and zinc treatment. ConclusionThe present study provided the first evidence that ZnT8 transports Zn into Leydig cell mitochondria with gonadotropin stimulation and suggests that ZnT8 may play a role in testosterone production via the PKA signaling pathway.

Fertility impairment with defective spermatogenesis and steroidogenesis in male zebrafish lacking androgen receptor.

The pivotal role of androgen receptor (AR) in regulating male fertility has attracted much research attention in the past two decades. Previous studies have shown that total AR knockout would lead to incomplete spermatogenesis and lowered serum testosterone levels in mice, resulting in azoospermia and infertility. However, the precise physiological role of ar in controlling fertility of male fish is still poorly understood. In this study, we have established an ar knockout zebrafish line by transcription activator-like effectors nucleases. Homozygous ar mutant male fish with smaller testis size were found to be infertile when tested by natural mating. Intriguingly, a small amount of mature spermatozoa was observed in the ar mutant fish. These mature spermatozoa could fertilize healthy oocytes, albeit with a lower fertilization rate, by in vitro fertilization. Moreover, the expression levels of most steroidogenic genes in the testes were significantly elevated in the ar mutants. In contrast, the levels of estradiol and 11-ketotestosterone (11-KT) were significantly decreased in the ar mutants, indicating that steroidogenesis was defective in the mutants. Furthermore, the protein level of LHβ in the serum decreased markedly in the ar mutants when compared with wild-type fish, probably due to the positive feedback from the diminished steroid hormone levels.

Sulforaphane Prevents Testicular Damage in Kunming Mice Exposed to Cadmium via Activation of Nrf2/ARE Signaling Pathways.

Sulforaphane (SFN) is a natural and highly effective antioxidant. Studies suggest that SFN protects cells and tissues against cadmium (Cd) toxicity. This study investigated the protective effect of SFN against oxidative damage in the testes of Kunming mice exposed to cadmium, and explored the possible molecular mechanisms involved. Cadmium greatly reduced the serum testosterone levels in mice, reduced sperm motility, total sperm count, and increased the sperm deformity rate. Cadmium also reduces superoxide dismutase (T-SOD) and glutathione (GSH) levels and increases malondialdehyde (MDA) concentrations. SFN intervention improved sperm quality, serum testosterone, and antioxidant levels. Both mRNA and protein expression of mouse testicular nuclear factor-erythroid 2-related factor 2 (Nrf2) was reduced in cadmium-treated group. Furthermore, the downstream genes of Nrf2, glutathione peroxidase (GSH-Px), γ-glutamyl cysteine synthetase (γ-GCS), heme oxygenase-1 (HO-1), and NAD(P)H:quinone oxidoreductase-1 (NQO1) were also decreased in cadmium-treated group. SFN intervention increases the expression of these genes. Sulforaphane prevents cadmium-induced testicular damage, probably via activation of Nrf2/ARE signaling.

Discovery of ODM-201, a new-generation androgen receptor inhibitor targeting resistance mechanisms to androgen signaling-directed prostate cancer therapies.

Activation of androgen receptor (AR) is crucial for prostate cancer growth. Remarkably, also castration-resistant prostate cancer (CRPC) is dependent on functional AR, and several mechanisms have been proposed to explain the addiction. Known causes of CRPC include gene amplification and overexpression as well as point mutations of AR. We report here the pharmacological profile of ODM-201, a novel AR inhibitor that showed significant antitumor activity and a favorable safety profile in phase 1/2 studies in men with CRPC. ODM-201 is a full and high-affinity AR antagonist that, similar to second-generation antiandrogens enzalutamide and ARN-509, inhibits testosterone-induced nuclear translocation of AR. Importantly, ODM-201 also blocks the activity of the tested mutant ARs arising in response to antiandrogen therapies, including the F876L mutation that confers resistance to enzalutamide and ARN-509. In addition, ODM-201 reduces the growth of AR-overexpressing VCaP prostate cancer cells both in vitro and in a castration-resistant VCaP xenograft model. In contrast to other antiandrogens, ODM-201 shows negligible brain penetrance and does not increase serum testosterone levels in mice. In conclusion, ODM-201 is a potent AR inhibitor that overcomes resistance to AR-targeted therapies by antagonizing both overexpressed and mutated ARs. ODM-201 is currently in a phase 3 trial in CRPC.

Abstract 5560: Characterization of a new non-steroidal small molecule inhibitor of CYP17 for castration-resistant prostate cancer.

Abstract Prostate cancer affects 1 in 6 men and is the second most common cause of cancer-related death. Since the majority of prostate cancers critically depend on androgens for growth, androgen deprivation therapy is a frontline treatment for advanced prostate cancer. The majority of prostate tumors initially respond to androgen deprivation therapy, but eventually the disease often progresses to castration-resistant prostate cancer. However, the current therapies that only reduce androgen produced in the testis do not affect androgen produced by adrenal glands can also produce androgens. This extra-testicular androgen production is thought to be a key factor in the development of castration resistant prostate cancer. CYP17 is a P450 enzyme that catalyzes the last step of androgen biosynthesis in both the testis and the adrenals. Inhibition of CYP17 therefore completely blocks androgen production and it is thus thought to be more effective to prevent prostate cancer progression than current therapies. Angion Biomedica has identified a promising series of proprietary non-steroidal CYP17 inhibitors. Our lead compound is potent, orally bioavailable, and significantly reduces serum testosterone levels in mice. Treatment of rats and mice with our lead CYP17 inhibitor significantly reduces the weights of androgen dependent organs. In two mouse xenograft models of androgen-dependent tumor growth our lead CYP17 inhibitor markedly reduces primary tumor growth, serum testosterone and PSA levels. Angion is currently further evaluating the therapeutic potential of this series of compounds as a possible therapy for castration resistant prostate cancer. Citation Format: Bert Oehlen, Siobhan McCormack, Gaifeng Ma, Dong Sung Lim, Bijoy Panicker, Itzhak D. Goldberg. Characterization of a new non-steroidal small molecule inhibitor of CYP17 for castration-resistant prostate cancer. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 5560. doi:10.1158/1538-7445.AM2013-5560

Effects of andrographolide on sexual functions, vascular reactivity and serum testosterone level in rodents

In this study, effects of andrographolide from Andrographis paniculata on sexual functions, vascular reactivity and serum testosterone level in experimental animals were observed. The suspension of andrographolide in 5% DMSO was administered orally at the dose of 50mg/kg to male ICR mice. The female mice involved in mating were made receptive by hormonal treatment. The mating behaviors, mounting latency and mounting frequency, were determined and compared with the standard reference drug sildenafil citrate. Administration of andrographolide significantly decreased the mounting latency at 120 and 180min and increased mounting frequency at 180min after treatment. In endothelium-intact rat aortic strips, norepineprine-induced contraction was reduced by preincubation with andrographolide. Administration of 50mg/kg andrographolide orally to male mice once daily for 2, 4, 6 or 8weeks had no significant effects on sperm morphology and motility. Interestingly, at week 4, serum testosterone level in mice treated with andrographolide was significantly increased when compared to the control. Thus, the effects of andrographolide on vascular response to norepinephrine and testosterone level observed in this study might be contributed to the sexual enhancing properties observed.