The impact of cigarette smoking on protamines 1 and 2 transcripts in human spermatozoa

This study was conducted to evaluate the relation between cigarette smoking, semen quality and ratios of protamine mRNAs in smokers and non-smokers. Spermatozoa from 123 men and 64 smokers and 59 non-smokers whose female partners attended an assisted reproduction and andrology laboratory were evaluated. Protamine mRNA was extracted from purified sperm, reverse-transcribed and subjected to real-time quantitative PCR using specific primer pairs for protamine 1 (PRM1) and protamine 2 (PRM2). The main outcomes showed that PRM1 mRNA levels in smokers were significantly lower (p = 0.05) than that of non-smokers. Additionally, PRM2 mRNA levels in smokers were significantly lower (p = 0.001) than that of non-smokers. PRM1/PRM2 mRNA ratios in non-smokers samples show significant differences (p = 0.001) compared with those in smokers. PRM1/PRM2 mRNA ratios were negatively and significantly correlated (p = 0.001) with semen volume, sperm count and normal sperm morphology. We concluded that sperm quality and sperm protamine mRNAs were negatively affected by smoking, and these data will serve as new evidence for the hazardous effect of smoking on male fertility. Additionally, protamine transcripts ratios may serve as a marker for male fertility.