The impact of endocrine disruptors on spermatogonia survival: the case of methoxychlor

• Autor(a) principal: Raposo, Joana Filipa Rocha
• 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/10400.6/12524
• topic: Apoptose; Espermatogónias Tipo B; Metoxicloro; Recetores de Esteroides Sexuais; Sobrevivência; Stress Oxidativo; Domínio/Área Científica::Engenharia e Tecnologia::Bioquímica

Endocrine disruptors (EDCs) are xenobiotics that have the ability to interfere with hormone synthesis, secretion and metabolism, thus affecting the reproductive system. Today we are ubiquitously exposed to these compounds through various pathways, such as ingestion, inhalation and dermal absorption. Methoxychlor (MXC) is an organochloride pesticide with moderate persistence in the environment capable of adversely affecting spermatogenesis, deregulating the development of germ cells, and interfering with sperm function. Among germ cells, type B spermatogonia are the first differentiated germline cell population and the initiator of the spermatogenic process. However, little is known about the role of MXC in modulating the survival pathways of type B spermatogonia. In the present dissertation, the impact of MXC on survival/apoptosis, and on the antioxidant defences of spermatogonia, was studied. For this purpose, a type B spermatogonia cell line, the GC-1spg, was cultured in the presence (5, 10, 25, 50 and 100 µM) and without MXC for 48 hours. The effect of MXC on GC-1spg viability was analysed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium (MTT) bromide assays. Moreover, protein expression of key regulators of apoptosis, estrogen receptors alpha and beta (ERa and ERß, respectively) and androgen receptor (AR) was analysed by Western Blot and the activity of antioxidant enzymes and caspase-3 by colorimetric assays. The obtained results demonstrated that MXC decreases the viability of GC-1spg cells in a concentration-dependent manner, increasing the activity of the antioxidant enzymes superoxide dismutase and glutathione peroxidase, and caspase-3. Despite the increase in the Bax (pro-apoptotic protein)/Bcl-2 (anti-apoptotic protein) ratio, there was a decrease in caspase-8 and p53 expression in GC-1spg exposed to MXC. In addition, MXC treatment decreased the expression of both estrogen receptors (ERa and ERß) and AR in GC-1spg. The present study demonstrates the modulation of GC1-spg apoptosis by MXC, being the first to demonstrate the expression of ERß in GC-1spg and to show the impact of MXC on the expression of these sex steroid receptors. By investigating the mechanisms and pathways by which EDCs exert harmful effects on male reproductive health, the present study widens the horizons for the identification of targets for developing new strategies for preserving male fertility and eventual treatments.