Antioxidant Systems in Rat Epididymal Spermatozoa¹

^a Department of Biochemistry, Biophysics and Macromolecular Chemistry, University of Trieste, Trieste, Italy

Mammalian caput and cauda epididymidal spermatozoa exhibit diverse stages of maturation, and their plasma membrane shows diverse composition and stability levels, thus enabling these spermatozoa to undergo the acrosomal reaction after transit through the epididymis. As a result, the study of antiperoxidative mechanisms is quite relevant, since epididymal spermatozoa must be properly protected against agents such as reactive oxygen species, which can impair the complex maturation process. We considered activities of certain enzymes (glutathione peroxidase [GPx], phospholipid hydroperoxide glutathione peroxidase [PHGPx], glutathione reductase [GR], superoxide dismutase [SOD], and catalase [CAT]) and the vitamin E content in isolated rat caput and cauda epididymidal spermatozoa. The results indicate that caput epididymidal sperm have significantly greater PHGPx (3.5x), GPx (2.4x), and SOD (1.7x) activities, as well as a greater amount of vitamin E (3.8x). There were no detectable differences in the GR and CAT activities of caput and cauda epididymidal spermatozoa. The substantial drop in PHGPx activity during epididymal transit is discussed in relation to an additional function of this enzyme: the use of caput sperm protamines as a sulfhydryl substrate. In vitro peroxidation of the two sperm populations by the free radical generator (azo-initiator) 2,2'-azobis(2-amidinopropane) dihydrochloride revealed that only about 13% of the vitamin E content of the caput epididymidal spermatozoa was consumed, which contrasts with the greater consumption (about 70%) of the vitamin in cauda epididymidal spermatozoa. Selective inhibition of PHGPx, SOD, or CAT did not change this picture. The higher susceptibility of cauda epididymidal spermatozoa to radicals is discussed in relation to the diverse enzymatic activities, vitamin E content, and peroxidative response. These factors are correlated with the different stages of sperm cell maturation, which are characterized—from caput to cauda epididymidis—by progressive destabilization of the plasma and acrosomal membranes.

¹ Financial support by MURST (Rome) and by University of Trieste.

² Correspondence: Department of Biochemistry, Biophysics and Macromolecular Chemistry, University of Trieste, Via Giorgieri 1, 34127 Trieste, Italy. FAX: 39 40 676 3691; panfili{at}bbcm.univ.trieste.it

This article has been cited by other articles:

				C. P. Weir and B. Robaire Spermatozoa Have Decreased Antioxidant Enzymatic Capacity and Increased Reactive Oxygen Species Production During Aging in the Brown Norway Rat J Androl, March 1, 2007; 28(2): 229 - 240. [Abstract] [Full Text] [PDF]

				S. Wang, G. Wang, B. E. Barton, T. F. Murphy, and H. F. S. Huang Beneficial Effects of Vitamin E in Sperm Functions in the Rat After Spinal Cord Injury J Androl, March 1, 2007; 28(2): 334 - 341. [Abstract] [Full Text] [PDF]

				L. M. Wallock-Montelius, J. A. Villanueva, R. E. Chapin, A.J. Conley, H. P. Nguyen, B. N. Ames, and C. H. Halsted Chronic Ethanol Perturbs Testicular Folate Metabolism and Dietary Folate Deficiency Reduces Sex Hormone Levels in the Yucatan Micropig Biol Reprod, March 1, 2007; 76(3): 455 - 465. [Abstract] [Full Text] [PDF]

				A Glover and S J Assinder Acute exposure of adult male rats to dietary phytoestrogens reduces fecundity and alters epididymal steroid hormone receptor expression. J. Endocrinol., June 1, 2006; 189(3): 565 - 573. [Abstract] [Full Text] [PDF]

				J. Seligman, G. L. Newton, R. C. Fahey, R. Shalgi, and N. S. Kosower Nonprotein Thiols and Disulfides in Rat Epididymal Spermatozoa and Epididymal Fluid: Role of {gamma}-Glutamyl-Transpeptidase in Sperm Maturation J Androl, September 1, 2005; 26(5): 629 - 637. [Abstract] [Full Text] [PDF]

				E. V. Zubkova and B. Robaire Effect of Glutathione Depletion on Antioxidant Enzymes in the Epididymis, Seminal Vesicles, and Liver and on Spermatozoa Motility in the Aging Brown Norway Rat Biol Reprod, September 1, 2004; 71(3): 1002 - 1008. [Abstract] [Full Text] [PDF]

				M. K. Rao, C. M. Wayne, and M. F. Wilkinson Pem Homeobox Gene Regulatory Sequences That Direct Androgen-dependent Developmentally Regulated Gene Expression in Different Subregions of the Epididymis J. Biol. Chem., December 6, 2002; 277(50): 48771 - 48778. [Abstract] [Full Text] [PDF]

				H. Imai, K. Suzuki, K. Ishizaka, S. Ichinose, H. Oshima, I. Okayasu, K. Emoto, M. Umeda, and Y. Nakagawa Failure of the Expression of Phospholipid Hydroperoxide Glutathione Peroxidase in the Spermatozoa of Human Infertile Males Biol Reprod, February 1, 2001; 64(2): 674 - 683. [Abstract] [Full Text]

				R. BRIGELIUS-FLOHÉ and M. G. TRABER Vitamin E: function and metabolism FASEB J, July 1, 1999; 13(10): 1145 - 1155. [Abstract] [Full Text]