Endocrine Abstracts

Infertility affects about 15% of couples, and, among these, 50% are related to the male factor. Male infertility can be caused by intrinsic factors, and these may either directly or indirectly affect gamete and testicular development as a consequence of endocrinopathies. In that sense, research regarding the involvement of endocrine hormones, particularly of nutritional status-linked hormones, in the male reproductive system has increased over the years. In fact, the rise on the incidence of metabolic diseases is positively associated with a decrease in fertility rates, suggesting that nutritional status-linked hormones may play a role in the crosstalk between both conditions. Among the nutritional status-linked hormones, little is known concerning the role of insulin-like growth factors for several facets of testicular development, spermatogenesis, and steroidogenesis. IGF-1 was found to be expressed in multiple testicular cells and some germ cells, being the Sertoli cells their main source in the seminiferous tubules. IGF-2 mRNA has been found in human spermatozoa and is believed that IGF-2 is possibly produced by other cells of the male reproductive system, such as germ cells. However, the roles of both IGF-1 and IGF-2 for the male reproductive health and fertility outcomes remain poorly understood. Hence, the main goal of this work was to understand the contribution of IGF-1 and IGF-2 on male fertility. For that purpose, we identified and quantified the expression of IGF-1 and IGF-2 mRNA in spermatozoa samples of men (n=111) that underwent medically assisted reproduction (ART) treatments, through RT-PCR and RT-qPCR, respectively. We were able to identify for the first time, to the best of our knowledge, the expression of IGF-1 mRNA in human spermatozoa. In addition, we also positively identified the expression of IGF-2 mRNA in human spermatozoa. Further studies will disclosure the potential association between IGF-1 and IGF-2 mRNA expression and ART outcomes. The discovery of the expression of both IGF-1 and IGF-2 in human spermatozoa also opens the path for future studies concerning the role of nutritional status-linked hormones for male fertility and ART outcomes.