Evaluation of Enkephalin-Degrading Enzymes in Sperm from Heroin-Addicted Men

The aim of this study was to investigate two enkephalin-degrading enzymes, aminopeptidase N (APN/CD13) and endopeptidase (NEP/CD10), gene and protein expression levels in sperm samples of fertile and heroin-addicted men, and the correlation between their expressions and semen quality.

This case-control study, semen collected from 24 normozoospermic healthy (as a control group) and 24 heroin-addicted men donors (as case or addiction group). Sperm cells isolated by Cook Medical gradient (40%–80%) and followed up by swim-up techniques were used for real-time qPCR and flow cytometry techniques to assess APN/CD13 and NEP/CD10 genes and proteins subsequently. Semen parameters were analyzed by computer-assisted sperm analysis.

The findings revealed that sperm total motility (41.07 ±3.63 vs. 63.03 ± 3.31 %, p = 0.0001) and progressive motility (35.21 ± 2.64 vs. 20.93 ± 3.22%, p =0.001), and viability (69.9 ± 4.69 vs. 86.81 ± 1.26 %, p =0.002) were significant differences in addicted group vs. control ones. APN and NEP gene expression levels in the addicted group decreased compared with the control ones (1.00 ± 0.67 vs. 0.36 ± 0.13, p = 0.008 and 1.07 ± 0.11 vs. 0.52 ± 0.12 0.002, respectively). Flow cytometry analysis showed that the average percent of APN/CD13 in heroin consumers significantly decreased compared with the healthy ones, while NEP/CD10 rate between two groups was similar. We also observed that duration of drug dependence is correlated with sperm viability (r =-0.627, p =0.016) and motility (r= -0.410, p= 0.05), NEP (r= -0.434, p= 0.049), and APN (r -0.641, p= 0.002) gene expression levels.

We concluded that semen quality and enkephalin-degrading enzymes were altered in heroin-addicted men.