Hypogonadism and aquaglyceroporins in Sertoli cells

• Autor(a) principal: Nunes, Diana Filipa Cacheira
• Data de Publicação: 2022
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10773/35636
• topic: Male infertility; Testosterone; Follicle-stimulating hormone; Hypogonadism; Hormonal imbalance; Osmoregulation; Aquaporins; Sertoli cells

Male hypogonadism is a hormonal pathology characterized by low plasma testosterone levels. Decreased circulating testosterone levels are known to be directly related to poor fertility outcomes and decreased sperm quality. Sertoli cells (SCs) ensure an adequate ionic and nutritional environment for spermatogenesis. These cells are highly responsive to multiple hormones, with several of their membrane transporters being modulated by hormonal fluctuations. Glycerol is a metabolite crucial for the maintenance of the blood-testicular barrier, with high concentrations negatively impacting the spermatogenic event. Aquaglyceroporins, a subfamily of aquaporins (AQPs), mediate the passage of glycerol through the biological membranes and their activity is thought to be regulated by hormones. Nevertheless, the effects of chronic hormonal changes on the expression and function of AQPs in SCs have not yet been fully elucidated. This work aims to explore comparatively the impact of hormonal dysregulation associated with primary and secondary hypogonadism in the expression and function of aquaglyceroporins in human and mouse SCs (TM4 cell line). Mouse and human SCs were chronically exposed (during 72 hours) to different concentrations of follicle-stimulating hormone (FSH) and testosterone mimicking primary hypogonadism, secondary hypogonadism, and physiological situation. Then, AQPs gene expression was assessed by conventional PCR and quantitative PCR, AQPs protein expression was assessed by WB and AQPs function by analysis of glycerol membrane permeability via Stopped-Flow Light Scattering (SFLS). For the first time, we were able to identify AQP3 in human SCs and AQP7 in human and mouse SCs. Furthermore, our relative mRNA abundance results demonstrate there is an increased abundance of AQP7 gene in human SCs that are exposed to conditions mimicking secondary hypogonadism relative to SCs that are exposed to conditions mimicking primary hypogonadism. Additionally, positive correlations were found between AQPs 3 and 9 in a mimicking context of the physiological environment in mice, between AQPs 7 and 9 in the face of primary hypogonadism mimicking in mice, between AQPs 7 and 9 in the face of secondary hypogonadism mimicking in humans, and between AQPs 7 and 3 in the face of primary hypogonadism mimicking in both species. No significant differences were observed regarding protein expression. Nevertheless, significant changes in membrane permeability to glycerol were observed in SCs treated with hormone levels that mimicked primary hypogonadism in both human and mouse compared to the physiological situation. All this suggests that, despite the preliminary nature of these findings, AQPs appear to contribute to infertility in different types of hypogonadism and may be an important therapeutic target in cases of male (sub)infertility related to hormonal imbalances.