Downregulation of testosterone production through luteinizing hormone receptor regulation in male rats exposed to 17α-ethynylestradiol

Abstract

The pharmaceutical 17α-ethynylestradiol (EE2) is considered as an endocrine-disrupting chemical that interferes with male reproduction and hormonal activation. In this study, we investigated the molecular mechanism underlying EE2-regulatory testosterone release in vitro and in vivo. The results show that EE2 treatment decreased testosterone release from rat Leydig cells. Treatment of rats with EE2 reduced plasma testosterone levels and decreased the sensitivity of human chorionic gonadotropin (hCG). EE2 reduced luteinizing hormone receptor (LHR) expression associated with decreased cAMP generation by downregulation of adenylyl cyclase activity and decreased intracellular calcium-mediated pathways. The expression levels of StAR and P450scc were decreased in Leydig cells by treatment of rats with EE2 for 7 days. The sperm motility in the vas deferens and epididymis was reduced, but the histopathological features of the testis and the total sperm number of the vas deferens were not affected. Moreover, the serum dihydrotestosterone (DHT) level was decreased by treatment with EE2. The prostate gland and seminal vesicle atrophied significantly, and their expression level of 5α-reductase type II was reduced after EE2 exposure. Taken together, these results demonstrate an underlying mechanism of EE2 to downregulate testosterone production in Leydig cells, explaining the damaging effects of EE2 on male reproduction.The endocrine system precisely mediates sexual development and reproductive ability through circulating sexual hormones, which act as signaling molecules to render adequate regulation. Endocrine-disrupting chemicals (EDCs) are natural or industrial chemicals that are released into the environment through industries, livestock activities, domestic wastewater, and hospital effluence 1,2 . Numerous studies have indicated that EDCs interfere with endogenous endocrine processes by mimicking hormonal action, leading to infertility, metabolic syndrome, and the rise of cancer incidence 3-5 . In humans, increasing studies have indicated that EDCs have detrimental effects on the reproductive system, resulting in poor sperm quality and testicular dysgenic occurrence in men 6,7 , and disorders of ovulation and the uterus as well as a rise in breast cancer incidences in women 8,9 . Hence, the risks of EDCs are a global health issue 10 .EE2 has been reported to exert a higher estrogenic activity than estradiol (E2), and is extremely stable against oxidation by metabolism or degradation in the human body due to the property of the ethynyl group in the C 17 position [11][12][13] . This characteristic potentially allows 17α-ethynylestradiol (EE2) to pass into the environment 14,15 . Therefore, it is reasonable to consider environmental EE2 to be an EDC and have deleterious effects on the health of both animals and human beings 15 . The pharmaceutical EE2 is a synthetic estrogen widely used as an oral contraceptive pill, but abundant animal studies have also reported that long-term exposure to EE2 interferes with the biological ...

Effect of High-Fructose Diet-Induced Metabolic Syndrome on the Pituitary-Gonadal Axis in Male Rats

“…Interestingly, testosterone release, in response to hCG (0.05 IU/mL), was increased significantly in rat Leydig cells and purified from the fructose-fed group compared to the normal group ( Figure 3 ). The hCG dosage is enough to induce the maximum steroidogenic response, as shown in our previous experimental studies [ 20 , 21 ]. To determine whether the fructose-rich diet also can affect the cAMP/PKA pathway, the main downstream mechanism of the LH receptor, the cAMP analog (8-Br-cAMP), and the PKA activator (forskolin) were utilized at 10 −5 M. A nonstatistically significant elevation of testosterone release was found between the two groups in response to 8-Br-cAMP and forskolin.…”

“…Animals were sacrificed, and the testes were decapsulated. Leydig cells were isolated and digested by collagenase and Percoll separation, as our previous study described [ 20 , 21 ]. In brief, testicular interstitial cells were isolated after collagenase digestion and centrifugation.…”

“…We used a radioimmunoassay (RIA) (sensitivity 10 pg/mL, intra-assay coefficients of variation (CV) 4.1%, inter-assay 4.7%) to determine plasma and media testosterone levels [ 20 , 21 ].…”

“…The sperm vitality was evaluated according to our previous study [ 21 ]. The rat cauda epididymis was cut into two pieces and incubated with gentle shaking in 1% BSA-M199 medium for 10 min at 34 °C.…”

Circle(s) of Life: The Circadian Clock from Birth to Death

“…As a result, the ability of females in terms of reproduction rapidly drops to zero, whereas andropause in men is characterized by a rather gradual reduction in testosterone levels over decades [ 152 ]. This testosterone level reduction, however, has only little effect on the viability of sperm cells and, thus, the principal ability to reproduce [ 153 , 154 , 155 ].…”