%0 Journal Article
%A Vicente Carrillo, Alejandro
%A Álvarez Rodríguez, Manuel
%A Rodríguez Martínez, Heriberto
%T The mu (μ) and delta (δ) opioid receptors modulate boar sperm motility
%D 2016
%@ 1040-452X
%U https://hdl.handle.net/20.500.14352/104453
%X Endogenous and exogenous opioids modulate reproductive functions in target cells via opioid receptors (μ, δ, and κ). Sperm motility is a metric of gamete functionality, and serves as a suitable parameter for in vitro drug-induced toxicity assays. This study identifies the presence and location of opioid receptors in pig spermatozoa as well as their functional response after in vitro challenge with known agonists (morphine [μ]; [D-Pen 2,5]-enkephanile [δ]; and U 50488 [κ]) and antagonists (naloxone [μ]; naltrindole [δ]; and nor-binaltrorphimine [κ]). Only the μ- and δ-opioid receptors were present in the boar sperm plasma membrane, overlying the acrosome, neck, and principal piece. Challenge experiments with agonists and antagonists identified both μ- and δ-opioid receptors as regulators of sperm kinematics, wherein μ maintains or increases sperm movement whereas δ decreases sperm motility over time.
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