The Effect of Interaction NGF/p75^NTR in Sperm Cells: A Rabbit Model

Nerve Growth Factor (NGF) plays an important role in the reproductive system through its receptor's interaction (p75^NTR). This paper aims to analyze the impact of NGF p75^NTR in epididymal and ejaculated rabbit semen during in vitro sperm storage.

Semen samples from 10 adult rabbit bucks were collected four times (n = 40) and analyzed. NGF was quantified in seminal plasma, and the basal expression of p75^NTR in sperm was established (time 0). Moreover, we evaluated p75^NTR, the apoptotic rates, and the main sperm parameters, at times 2-4 and 6 h with or without the administration of exogenous NGF.

Based on the level of p75^NTR, we defined the threshold value (25.6%), and sperm were divided into High (H) and Normal (N). During sperm storage, p75^NTR of H samples significantly modulated some relevant sperm parameters. Specifically, comparing H samples with N ones, we observed a reduction in motility and non-capacitated cell number, together with an increased percentage of dead and apoptotic cells. Notably, the N group showed a reduction in dead and apoptotic cells after NGF treatment. Conversely, the NGF administration on H sperm did not change either the percentage of dead cells or the apoptotic rate.

The concentration of p75^NTR on ejaculated sperm modulates many semen outcomes (motility, apoptosis, viability) through NGF interaction affecting the senescence of sperm.