Possible involvement of brain-derived neurotrophic factor in male infertility

Abstract

Brain-derived neurotrophic factor (BDNF) plays a role in the development of various non-neuronal tissues, as the reproductive system. BDNF transcript and protein has been detected in testis and sperms. The present work aimed to assess the possible involvement of BDNF mRNA expression in sperm functions, hormonal profile and oxidative stress in male infertility. Semen samples from 106 individuals attended the Andrology Outpatient Clinic, Mansoura University Hospital were included in the present study. They were grouped into normozoospermia (n= 31), asthenozoospermia (n= 24), astheno-teratozoospermia (n= 25) and Oligo-astheno-teratozoospermia (n= 26). Reverse transcription-PCR (RT-PCR) for brain-derived neurotrophic factor (BDNF) mRNA expression was done for semen samples. The present study demonstrated that BDNF mRNA expression was significantly decreased in the infertile samples compared with the normozoospermic group. BDNF mRNA expression was significantly positively correlated to testosterone levels (r= 0.337, p= 0.0004) while, negatively correlated to folliclestimulating hormone (FSH) (r= - 0.5, p 0.0001) and malondialdehyde (MDA) /sperm levels (r= - 0.735, p0.0001). Also, the study showed significant positive correlation (p<0.0001) between BDNF mRNA expression and sperm motility, velocity, linear velocity and linearity index. Stepwise multiple regression analysis showed that sperm morphology and alpha glucosidase may be possible determinants that influence changes of BDNF expression. BDNF mRNA may directly affect sperm functions and may be implicated in the pathophysiology of infertility. Furthermore, BDNF may have protection against oxidative stress.

Keywords: Brain-Derived Neurotropic Factor (BDNF) mRNA expression, Infertility, Sperm function, Oxidative stress.