Minimizing sperm oxidative stress using nanotechnology for breeding programs in rams.

Abstract

Background Artificial insemination (AI) is a routine breeding technology in animal reproduction. Nevertheless, the temperature-sensitive nature and short fertile lifespan of ram sperm samples hamper its use in AI. In this sense, nanotechnology is an interesting tool to improve sperm protection due to the development of nanomaterials for AI, which could be used as delivery vehicles. In this work, we explored the feasibility of nanoemulsions of vitamin E (NE) for improving sperm quality during transport. Results With the aim of evaluating this proposal, ejaculates of seven mature rams of Manchega breed were collected by artificial vagina and extended to 60 x 106 spz/mL in Andromed®. Samples containing control and NE (12 mM) with and without exogenous oxidative stress (100 µM Fe2+/ascorbate) were stored at 22 and 15 ºC and motility (CASA), viability (YO-PRO/IP), acrosomal integrity (PNA-FITC/IP), mitochondrial membrane potential (Mitotracker Deep Red 633), lipoperoxidation (C11 BODIPY 581/591), intracellular reactive oxygen species (ROS) production and DNA status (SCSA®) monitored during 96 hours. Our results show that NE could be used to maintain ram spermatozoa during transport at 15 ºC and 22 ºC for up to 96 h, with no appreciable loss of kinematic and physiological characteristics of freshly collected samples. Conclusions The storage of ram spermatozoa in liquid form for 2-5 days with vitamin E nanoemulsions may lead more flexibility to breeders in AI programs. In view of the potential and high versatility of these nanodevices, further studies are being carried out to assess the proposed sperm preservation medium on fertility after artificial insemination.