THE ACTIVITY AND ISOFORMS OF SUPEROXIDE DISMUTASE IN TISUES OF REPRODUCTIVE ORGANS OF RATS

Abstract

The aсtivity of superoxide dismutase, the content of its isoforms in testis, epididimis, and in epididimal spermatozoa of pubescent rat males were studied. The experiments were performed on adult male rats (age 5 - 6 months). After decapitation, the testes and the epididimis were taken, from which the spermatozoa were washed with 0.9 % sodium chloride solution. The total protein and activity of superoxide dismutase (SOD) were determined in the supernatant and the sperm suspension. SOD isoforms were detected after electrophoresis in 10 % polyacrylamide gel by specific staining of gel plates with nitrosine tetrazolium. The highest activity was found to be in the tissue of the testes (18.2 ± 2.59 IU/mg of protein), less on 34.6% in the epididymis and the lowest on 46.7% in epididymal sperm. Electrophoresis in 10 % polyacrylamide gel and specific staining in the tissues of testis, epididymis, and epididymal sperm of rats revealed five major SOD isoforms, which, depending on the speed of movement in PAAG, were labeled, from maximum to least mobile, such as S1, S2, S3, S4 and S5. The specifity of testicular tissue is the presence of two minor isoforms (S1a- and S1b-isoforms), which are characterized by high electrophoretic mobility and lower intensity of manifestation, and the color disappears over time, unlike other proteins of the enzyme. It was found that the SOD isoenzyme spectrum is characterized by tissue specificity and depended on the physiological and functional features of the tissue of the reproductive organs of males and spermatozoa. In the testis tissue, S2 isoform was in the largest amount– 36.7 ± 1.91%, less and almost the same content of S1-, S3- and S4-isoforms (18.0 ± 3.27, 19.3 ± 3.98 and 15.7 ± 2.15%) and the least – S5-, S1a- and S1b-isoform (6.2 ± 1.20%; 2.2 ± 0.03 and 1.9 ± 0.01%). In the epididimis tissue, the content of the S3-isoform was higher on 17.9% and S2- and S1- respectively on 7.9% and 4.9%, respectively, compared to the testis. SOD isoenzymes of epididymal spermatozoa are characterized by a high content of S2 isoforms, which is more on 11.2% than in the testis, and the content of S1 isoforms, by contrast, is lower on 10.0%. The established differences in the content and activity of individual isoforms of the enzyme indicate the existence of tissue specificity of SOD proteins, due to the functional characteristics of the studied tissues. Optimal protection of sperm from O2• - in the process of their differentiation and maturation is ensured by the activity of different SOD isoforms, confirming the established differences in the isoenzyme spectrum.