Abstract
The proper transition of histones to protamine during spermiogenesis is critical for male fertility. This study aimed to quantify the levels of histones and protamines mRNA in sperms of infertile couples and their possible effect on the sperm's quality and chromatin integrity. Spermatozoa from 53 normal and 75 patients were enrolled in this study. Histones and Protamine mRNAs were extracted, reverse-transcribed and applied to real-time quantitative PCR. Chromomycin A3 staining was used to assess protamination and chromatin integrity, and Eosin-Nigrosine-Test and HOS-Test was used to evaluate the sperm's vitality and membrane integrity respectively. Levels of histones H2A and H2B mRNA in patient's sperms were significantly (p < 0.01) higher than that of normal (31.22 ± 2.91, 30.03 ± 2.05 vs. 25.62 ± 1.98, 27.23 ± 3.04, respectively). Protamine PRM2 mRNA in patient's sperms (20.55 ± 2.01) was significantly lower than in normal (21.73 ± 2.64, p < 0.01). The PRM1/PRM2 and H2A/H2B mRNAs ratios were significantly higher (p < 0.01) in patients than normal (1.02 ± 0.10, 1.04 ± 0.07 vs. 0.98 ± 0.06, 0.94 ± 0.08 respectively). Also, the sperm's nuclear histones to protamines transcripts ((H2A + H2B)/(PRM1 + PRM2)) ratios of patients (1.49 ± 0.16) was significantly higher (p < 0.01) than that of normal (1.25 ± 0.15). Histone/protamine transcripts [((H2A + H2B)/(PRM1 + PRM2)) mRNAs ratios] were negatively correlated (p < 0.05) with sperm's count, total count, motility, progressive motility, normal morphology, membrane integrity and positively with chromatin decondensation. The data suggests that histones/protamines mRNAs ratios are important for a sperm's quality and therefore could be used as predictors for male infertility. Also, validation study may be required to confirm the study conclusion.