%0 Journal Article
%T Functional Importance of 1¦Á,25(OH)2-Vitamin D3 and the Identification of Its Nongenomic and Genomic Signaling Pathways in the Testis
%A F¨¢tima Regina Mena Barreto Silva
%J Advances in Andrology
%D 2014
%R 10.1155/2014/808906
%X The 1¦Á,25(OH)2-vitamin D3 (1,25-D3) is known by its classic effects on Ca2+ metabolism and regulation of cellular proliferation and differentiation. The hormone 1,25-D3 acts in the testis through nongenomic and genomic events being implicated in the success of spermatogenesis in rats and in human being. The aim of this review was to highlight the effect and intracellular pathways of 1,25-D3 to modulate the spermatogenesis. The pivotal role of 1,25-D3 in male reproduction is reinforced by the presence of VDR and 1¦Á-hydroxylase in reproductive tract. Also, the marked expression of VDR and the VD metabolizing enzymes in human testis, ejaculatory tract, and mature spermatozoa implicates the 1,25-D3 in spermatogenesis and maturation of human spermatozoa. Among genomic events, 1,25-D3 influences the expression of calcium binding protein and stimulates aromatase gene expression through a nongenomic activation of the membrane-bound VDR receptor involving the PKA pathway in the testis. Also, 1,25-D3 stimulates amino acid transport and exocytosis in testis by nongenomic events coupled to ionic currents triggered at plasma membrane. All together, the demonstration that 1,25-D3 regulates both Sertoli cell and sperm function may be useful for the study and development of new therapeutic strategies for the male reproductive disorders. 1. General Aspects The first scientific report associated with vitamin D deficiency and bone disease rickets was around 1645. However, the recognition of the rickets in patients with no sunshine exposition was only in the 20th century. In 1924, an additional key for vitamin D present in skin was the discovery that a precursor of vitamin D could be converted into vitamin D by exposure to sunlight or ultraviolet [1]. The hallmark era of vitamin D began in 1965¨C1970 since the chemical characterization of an active metabolite of vitamin D, 1¦Á,25(OH)2-vitamin D3 (1,25-D3), and its nuclear receptor (VDR) was reported [1, 2]. It is known that vitamin D3 does not have any intrinsic biological activity [3]. After the knowledge that the precursor of vitamin D can be converted into vitamin D by exposure to ultraviolet light (UVB), it is now comprehensive that vitamin D is correctly named as vitamin only when sunlight exposure does not exist [4]. Nowadays, the biologically active form of vitamin D is known to be a steroid hormone and endocrine system of vitamin D is well accepted. The chemical characterization, the production of an active metabolite of 1,25-D3, and its nuclear receptor occurred between 1965¨C1970 [5]. The interesting thing about
%U http://www.hindawi.com/journals/aandrol/2014/808906/