Effect of the neonicotinoid acetamiprid on molecular events during in vitro boar spermatozoa capacitation

Acetamiprid (Ace) is a widely used neonicotinoid insecticide whose intensive application in agriculture has raised concerns about its potential effects on the reproductive health of animals and humans. Successful fertilization depends on the integrity of the plasma membrane (PM) of the spermatozoa and the proper progression of the series of events involved in capacitation. The aim of this study was to evaluate the effects of Ace on the capacitation of boar spermatozoa and several associated functional parameters: membrane carbohydrate redistribution, membrane microdomains (MDM), cholesterol efflux, mitochondrial membrane potential (ΔΨm), DNA integrity, motility, and the capacity to achieve the acrosome reaction (AR). The median lethal concentration (LC50) of Ace was estimated by PROBIT analysis at 590 µM after testing ¹/₅ LC50, ½ LC50, and LC50. We found that Ace increased PM damage and was associated with reduced cholesterol efflux, capacitation, and AR, as well as altered distributions of N-acetylglucosamine and sialic acid residues and MDM. Ace significantly impaired membrane functionality during capacitation and increased both the number of spermatozoa with high ΔΨm and DNA damage. These results may be a consequence of damage to the PM function and the physiology of the spermatozoa, especially in processes related to capacitation and the AR. These effects have potential implications for the fertility of exposed populations.