Single microcystin exposure impairs the hypothalamic-pituitary-gonadal axis at different levels in female rats.

Microcystin (MC) is most common cyanobacterial toxin. Few studies have evaluated the MC effects on the hypothalamic-pituitary-gonadal (HPG) axis and metabolic function. In this study, we assessed whether MC exposure results in HPG axis and metabolic changes. Female rats were exposed to a single dose of MC at environmentally relevant levels (5, 20 and 40 µg/kg). After 24 h, we evaluated reproductive and metabolic parameters for 15 days. MC reduced the hypothalamic GnRH protein expression, increased the pituitary protein expression of GnRHr and IL-6. MC reduced LH levels and increased FSH levels. MC reduced the primary follicles, increased the corpora lutea, elevated levels of anti-Müllerian hormone (AMH) and progesterone, and decreased estrogen levels. MC increased ovarian VEGFr, LHr, AMH, ED1, IL-6 and Gp91-phox protein expression. MC increased uterine area and reduced endometrial gland number. A blunted estrogen-negative feedback was observed in MC rats after ovariectomy, with no changes in LH levels compared to intact MC rats. Therefore, these data suggest that a MC leads to abnormal HPG axis function in female rats.

Chlorothalonil as a potential endocrine disruptor in male zebrafish (Danio rerio): Impact on the hypothalamus-pituitary-gonad axis and sperm quality.

Chlorothalonil is a broad-spectrum organochlorine fungicide widely employed in agriculture to control fungal foliar diseases. This fungicide enters aquatic environments through the leaching process, leading to toxicity in non-target organisms. Organic contaminants can impact organism reproduction as they have the potential to interact with the neuroendocrine system. Although there are reports of toxic effects of chlorothalonil, information regarding its impact on reproduction is limited. The aim of the present study was to evaluate the influence of chlorothalonil on male reproductive physiology using the zebrafish (Danio rerio) as ecotoxicological model. Zebrafish were exposed for 7 days to two concentrations of chlorothalonil (0.1 and 10 µg/L) along with a control group (with DMSO - 0.001%). Gene expression of hypothalamus-pituitary-gonad axis components (gnrh2, gnrh3, lhr, fshr, star, hsd17b1, hsd17b3, and cyp19a1), as well as hepatic vitellogenin concentration were assessed. In sperm cells, reactive oxygen species (ROS) content, lipid peroxidation (LPO), mitochondrial functionality, and membrane integrity and fluidity were evaluated. Results indicate that exposure to the higher concentration of chlorothalonil led to a reduction in brain gnr2 expression. In gonads, mRNA levels of lhr, star, and hsd17b1 were decreased at both chlorothalonil concentrations tested. Similarly, hepatic vitellogenin concentration was reduced. Regarding sperm cells, a decreased ROS level was observed, without significant difference in LPO level. Additionally, a higher mitochondrial potential and lower membrane fluidity were observed in zebrafish exposed to chlorothalonil. These findings demonstrate that chlorothalonil acts as an endocrine disruptor, influencing reproductive control mechanisms, as evidenced by changes in expression of genes HPG axis, as well as hepatic vitellogenin concentration. Furthermore, our findings reveal that exposure to this contaminant may compromise the reproductive success of the species, as it affected sperm quality parameters.

Hypothalamic-pituitary-gonadal axis disturbance and its association with insulin resistance in kidney transplant recipients.

OBJECTIVE: To evaluate hypothalamic-pi- tuitary-gonadal (HPG) axis alterations at 1 and 12 months after kidney transplan- tation (KT) and their association with in- sulin resistance. METHODS: A retrospective clinical study was conducted in a tertiary care center in kidney transplantation recipients (KTRs) aged 18- 50 years with primary kidney disease and stable renal graft function. LH, FSH, E2/T, and HOMA-IR were assessed at 1 and 12 months after KT. RESULTS: Twenty-five KTRs were included; 53% were men, and the mean age was 30.6±7.7 years. BMI was 22.3 (20.4-24.6) kg/m2, and 36% had hypogonadism at 1 month vs 8% at 12 months (p=0.001). Re- mission of hypogonadism was observed in all men, while in women, hypogonadotropic hypogonadism persisted in two KTRs at 12 months. A positive correlation between go- nadotrophins and age at 1 and 12 months was evident. Fifty-six percent of patients had insulin resistance (IR) at 1 month and 36% at 12 months (p=0.256). HOMA-IR showed a negative correlation with E2 (r=- 0.60; p=0.050) and T (r=-0.709; p=0.049) at 1 month, with no correlation at 12 months. HOMA-IR at 12 months after KT correlated positively with BMI (r=0.52; p=0.011) and tacrolimus dose (r=0.53; p=0.016). CONCLUSION: Successful KT restores the HPG axis in the first year. Hypogonadism had a negative correlation with IR in the early pe- riod after KT, but it was not significant at 12 months.

Quercetin Inhibits ROS-p53-Bax-caspase-3 axis of apoptosis and augments gonadotropin and testicular hormones in chronic unpredictable stress-Induced testis injury / La quercetina inhibe el eje de apoptosis ROS-p53-Bax-caspasa-3 y aumenta la gonadotropina y las hormonas testiculares en la lesión testicular inducida por estrés crónico e impredecible

SUMMARY: A large body of evidence supports the protective role of the flavonol antioxidant compound quercetin in mammals. We tested the hypothesis that quercetin can protect against the hypothalamus-pituitary-gonadal (HPG) axis defect like a reduction in gonadotropins and testicular hormones and abnormal semen analysis induced by chronic unpredictable stress (CUS), possibly via the downregulation of oxidative stress (ROS) and p53-Bax-caspase-3 pathways. Rats were either exposed to a variety of unpredictable stressors daily before being sacrificed after 3 weeks (model group) or were treated with quercetin (50 mg/kg body weight/day) at the same time the CUS were induced (treated group). Harvested testicular tissues were stained with basic histological staining, and testis homogenates were assayed for the tumor suppressor p53, apoptosis regulator Bax, B-cell lymphoma 2 (Bcl-2), caspase-3, malondialdehyde (MDA), glutathione peroxidase (GPx), and superoxide dismutase (SOD). In addition, harvested epididymis tissues were used to assess semen analysis, and blood samples were assayed for the testicular hormone testosterone, the adrenal cortex hormone corticosterone, and the anterior pituitary gonadotropins, follicular stimulating hormone (FSH) and luteinizing hormone (LH). CUS induced profound testicular damage and significantly (p<0.05) induced p53, Bax, caspase-3, MDA, and corticosterone, which were significantly (p<0.05) inhibited by quercetin except corticosterone. Whereas, quercetin significantly (p<0.05) increased FSH, LH, testosterone, Bcl-2, GPx, and SOD levels that were inhibited by CUS. In addition, CUS induced oligozoospermia, asthenozoospermia, and teratozoospermia, which were significantly (p<0.05) protected by quercetin. Thus, Quercetin protects against CUS-induced HPG defects in rats, which is associated with the inhibition of ROS-p53-Bax-caspase-3 axis.

RESUMEN: El papel protector del compuesto antioxidante flavonol quercetina en los mamíferos ha sido ampliamente reportado. Probamos la hipótesis que la quercetina puede proteger contra el defecto del eje hipotálamo-hipofisiario- gonadal (HHG) como una reducción de gonadotropinas y hormonas testiculares y análisis de semen anormal inducido por estrés crónico impredecible (ECI), posiblemente a través de la regulación reducida del estrés oxidativo (REO) y las vías p53- Bax-caspasa-3. Las ratas fueron expuestas a una variedad de fac- tores estresantes impredecibles diariamente antes de ser sacrificadas después de 3 semanas (grupo modelo) o fueron tratadas con quercetina (50 mg / kg de peso corporal / día) al mismo tiempo que se indujo la ECI (grupo tratado). Los tejidos testiculares fueron teñidos con tinción histológica básica y los homogeneizados de testículo se analizaron para determinar el supresor de tumores p53, el regulador de apoptosis Bax, el linfoma de células B 2 (Bcl-2), la caspasa-3, el malondialdehído (MDA), la glutatión peroxidasa (GPx) y superóxido dismutasa (SOD). Además, se utilizaron tejidos del epidídimo recolectados para evaluar el análisis de semen y se analizaron muestras de sangre para determinar la hormona testicular testosterona, la hormona corticosterona de la corteza suprarrenal y las gonadotropinas de la hipófisis anterior, la hormona estimulante folicular (FSH) y la hormona luteinizante (LH). El ECI indujo daño testicular importante e indujo significativamente niveles de (p <0,05) p53, Bax, caspasa-3, MDA y corticosterona, que fueron inhibidos (p <0,05) por la quercetina. La quercetina aumentó significativamente (p <0,05) los niveles de FSH, LH, testosterona, Bcl-2, GPx y SOD que fueron inhibidos por ECI. Además, ECI indujo oligozoospermia, astenozoospermia y teratozoospermia, protegidos de manera significativa (p <0,05) por la quercetina. Por lo tanto, la quercetina protege contra los defectos de HHG inducidos por ECI en ratas, lo que está asociado con la inhibición del eje ROS-p53-Bax-caspasa-3.