The role of vitamin D in male fertility: A focus on the testis

Abstract

In the last decade, vitamin D has emerged as a pleiotropic molecule with a multitude of autocrine, paracrine and endocrine functions, mediated by classical genomic as well as non-classical non-genomic actions, on multiple target organs and systems. The expression of vitamin D receptor and vitamin D metabolizing enzymes in male reproductive system, particularly in the testis, suggests the occurrence of vitamin D synthesis and regulation as well as function in the testis. The role of vitamin D in the modulation of testis functions, including hormone production and spermatogenesis, has been investigated in animals and humans. Experimental studies support a beneficial effect of vitamin D on male fertility, by modulating hormone production through genomic and non-genomic actions, and, particularly, by improving semen quality essentially through non-genomic actions. However, clinical studies in humans are controversial. Indeed, vitamin D seems to contribute to the modulation of the bioavailable rather than total testosterone. Moreover, although an increased prevalence or risk for testosterone deficiency was reported in men with vitamin D deficiency in observational studies, the majority of interventional studies demonstrated the lack of effect of vitamin D supplementation on circulating levels of testosterone. The most consistent effect of vitamin D was reported on semen quality. Indeed, vitamin D was shown to be positively associated to sperm motility, and to exert direct actions on spermatozoa, including non-genomic driven modulation of intracellular calcium homeostasis and activation of molecular pathways involved in sperm motility, capacitation and acrosome reaction. The current review provides a summary of current knowledge on the role of vitamin D in male fertility, by reporting clinical and experimental studies in humans and animals addressing the relationship between vitamin D and testis function.

Sedentary behavior, physical inactivity and body composition in relation to idiopathic infertility among men and women

“…However, higher volumes of television viewing time have been related to vitamin D deficiency [52], which has been associated with a lower percentage of motile spermatozoa compared to men with sufficient vitamin D levels [32,53]. Low levels of vitamin D are also related to obesity [54,55]. Adiposity, often associated with sedentary behavior and physical inactivity [56], increases oxidative stress, which may subsequently lead to gonad and gamete damage in men [57].…”

Novas perspectivas no papel da vitamina D e sua influência com a qualidade do sêmen e hormônios sexuais em homens

“…Um pré-requisito para um tecido ser alvo da ação da VD é a expressão do receptor VDR na membrana celular e, além dos níveis circulantes de 25(OH)D, a sua ação também depende da atividade das enzimas que a metabolizam, 25-hidroxilase e 1-αhidroxilase, que são expressas a partir dos genes, da família do citocromo P450, CYP27B1 e CYP2R1, respectivamente. (Hammoud et al, 2012;De Angelis et al, 2017). Tanto as enzimas quanto o receptor são simultaneamente expressos nos testículos, nas células de Sertoli, de Leydig, nas células germinativas, nos espermatozoides e nas células epiteliais que revestem o trato reprodutor masculino (Rojansky et al, 1992;Wehr et al, 2010;Ramlau-Hansen et al, 2011).…”

“…Esses achados sustentam a hipótese de que a VD pode ter uma influência na regulação dos níveis séricos de testosterona, embora os mecanismos de ação não estão ainda definidos. Os estudos sugerem um papel na regulação da testosterona, através de ações genômicas da VD nas células de Leydig (Sonnenberg et al, 1986;Inpanbutr et al, 1996;De Angelis et al, 2017).…”

“…Sua aplicação clínica é muito presente no diagnóstico, tratamento e prevenção do raquitismo, osteopenia e osteoporose (Holick, 2008;Holick et al, 2011) (Jensen, 2014). Contudo, o seu mecanismo de ação no sistema reprodutor ainda não é bem elucidado, mas tem sido consideravelmente investigada e reportada na literatura (Blomberg Jensen et al, 2010;Blomberg Jensen et al, 2011;Ramlau-Hansen et al, 2011;Blomberg Jensen e Dissing, 2012;Hammoud et al, 2012;Anic et al, 2016;Abbasihormozi et al, 2017;De Angelis et al, 2017).…”

“…Essas considerações estabelecem novos aspectos envolvidos na complexa patogênese da infertilidade(Blomberg Jensen, 2018). O papel da VD na qualidade seminal é mediado a partir da expressão do VDR e das enzimas que a metabolizam nos tecidos reprodutivos masculinos, demonstrados crescentemente na literatura científica em estudos clínicos e experimentais com animais e humanos(De Angelis et al, 2017).…”