Electromagnetic radiation at 900 MHz induces sperm apoptosis through bcl-2, bax and caspase-3 signaling pathways in rats

Abstract

Background: The decreased reproductive capacity of men is an important factor contributing to infertility. Accumulating evidence has shown that Electromagnetic radiation potentially has negative effects on human health. However, whether radio frequency electromagnetic radiation (RF-EMR) affects the human reproductive system still requires further investigation. Therefore, The present study investigates whether RF-EMR at a frequency of 900 MHz can trigger sperm cell apoptosis and affect semen morphology, concentration, and microstructure.

Methods: Twenty four rats were exposed to 900 MHz electromagnetic radiation with a special absorption rate of 0.66 ± 0.01 W/kg for 2 h/d. After 50d, the sperm count, morphology, apoptosis, reactive oxygen species (ROS), and total antioxidant capacity (TAC), representing the sum of enzymatic and nonenzymatic antioxidants, were investigated. Western blotting and reverse transcriptase PCR were used to determine the expression levels of apoptosis-related proteins and genes, including bcl-2, bax, cytochrome c, and capase-3.

Results: In the present study, the percentage of apoptotic sperm cells in the exposure group was significantly increased by 91.42% compared with the control group. Moreover, the ROS concentration in exposure group was increased by 46.21%, while the TAC was decreased by 28.01%. Radiation also dramatically decreased the protein and mRNA expression of bcl-2 and increased that of bax, cytochrome c, and capase-3.

Conclusion: RF-EMR increases the ROS level and decreases TAC in rat sperm. Excessive oxidative stress alters the expression levels of apoptosis-related genes and triggers sperm apoptosis through bcl-2, bax, cytochrome c and caspase-3 signaling pathways.

Fig. 1

The sketch diagram of exposure setup

Fig. 2

The optical micrographs of morphology of normal and malformed sperms. a The normal sperm. b The sperm cell with two tails. c The sperm cell with two heads. d The sperm cell with sharp head. e The sperm with no head. f The sperm cell with abnormal head

Fig. 3

Electron micrographs of sperm necks and tails. a The cross section of sperm tail from control group. b The ODF was lost in the sperm tail of exposure group mouse as the arrow pointing. c The normal linked structure between the head and tail in the sperm of control group. d the linked structure of the sperm in exposure group was swollen as arrow pointing

Fig. 4

The comparison in expressions of cytochrome c, bcl-2, bax and caspase-3 between the exposure and control. Densitometric analyses of cytochrome c, bcl-2, bax and caspase-3 in sperm of rats between exposure group and control group. The intensities of bcl-2, bax and caspase-3 were normalized with the β-actin and the intensity of cytochrome c was normalized with VDCA1. Bars represent Mean ± SEM (n = 15). *indicated a significant difference at P = 0.05

Fig. 5

The electrophoresis results of cytochrome c, bcl-2, bax and caspase-3. C represented control group and E represented exposure group. There were two bands in the gel of caspase-3 indicating the inactive (upper) and active (lower) caspase-3 proteins. The gel below the gel of cytochrome c protein represented VDCA1 and other 3 gels represented the β-actin

Fig. 6

The related expressions of bcl-2, bax, cytochrome c and caspase-3 genes in the sperms of the rats with different groups. The data was presented as Mean ± SEM (n = 15). *presented significant difference compared with the control group (P < 0.05)