title: Vitamin C and oxidative stress in the seminiferous epithelium.
abstract: In this article, we focus on the fundamental role of vitamin C transporters for the normal delivery of vitamin C to germ cells in the adluminal compartment of seminiferous tubules. We argue that the redox status within spermatozoa or in semen is partly responsible for the etiology of infertility. In this context, antioxidant defence plays a critical role in male fertility. Vitamin C, a micronutrient required for a wide variety of metabolic functions, has long been associated with male reproduction. Two systems for vitamin C transport have been described in mammals. Facilitative hexose transporters (GLUTs), with 14 known isoforms to date, GLUT1-GLUT14, transport the oxidized form of vitamin C (dehydroascorbic acid) into the cells. Sodium ascorbic acid co-transporters (SVCTs), SVCT1 and SVCT2 transport the reduced form of vitamin C (ascorbic acid). Sertoli cells control germ cell proliferation and differentiation through cell-cell communication and form the blood-testis barrier. Because the blood-testis barrier limits direct access of molecules from the plasma into the adluminal compartment of the seminiferous tubule, one important question is the method by which germ cells obtain vitamin C. Some interesting results have thrown light on this matter. Expression of SVCT2 and some isoforms of GLUT transporters in the testis have previously been described. Our group has demonstrated that Sertoli cells express functionally active vitamin C transporters. Kinetic characteristics were described for both transport systems (SVCT and GLUT systems). Sertoli cells are able to transport both forms of vitamin C. These findings are extremely relevant, because Sertoli cells may control the amount of vitamin C in the adluminal compartment, as well as regulating the availability of this metabolite throughout spermatogenesis.
authors.affiliation: Instituto de Bioquímica y Microbiología, Facultad de Ciencias, Universidad Austral de Chile, Valdivia, Chile. mcangulo@uach.cl
authors.forename: Constanza
authors.initials: C
authors.lastname: Angulo
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Maldonado
authors.forename: Eduardo
authors.initials: E
authors.lastname: Pulgar
authors.forename: Héctor
authors.initials: H
authors.lastname: Mancilla
authors.forename: Alex
authors.initials: A
authors.lastname: Córdova
authors.forename: Franz
authors.initials: F
authors.lastname: Villarroel
authors.forename: Maite A
authors.initials: MA
authors.lastname: Castro
authors.forename: Ilona I
authors.initials: II
authors.lastname: Concha
mesh_terms: D000818:Animals; D001205:Ascorbic Acid / Q000378:metabolism*; D001692:Biological Transport; D051246:Glucose Transport Proteins, Facilitative / Q000378:metabolism*; D006801:Humans; D007248:Infertility, Male / Q000378:metabolism; D008297:Male; D008322:Mammals; D051379:Mice; D018384:Oxidative Stress / Q000502:physiology*; D051381:Rats; D012670:Seminiferous Epithelium / Q000166:cytology* / Q000378:metabolism*; D012708:Sertoli Cells / Q000378:metabolism*; D060347:Sodium-Coupled Vitamin C Transporters / Q000378:metabolism*
chemical_list: D051246:Glucose Transport Proteins, Facilitative; D060347:Sodium-Coupled Vitamin C Transporters; D001205:Ascorbic Acid