Postthaw A-kinase anchoring protein 4 fluorescence intensity is associated with sperm motility, key kinematic parameters, and mitochondrial activity in goat spermatozoa

Abstract

Objective This study evaluated the relationship between postthaw A-kinase anchoring protein 4 (AKAP4) fluorescence intensity and spermatological parameters in cryopreserved goat semen. Methods Semen was collected weekly by electroejaculation during the nonbreeding season, diluted, and cryopreserved using an automated freezing system. Postthaw sperm were assessed for total motility, progressive motility, and kinematics using computer-assisted semen analysis. Flow cytometry evaluated plasma membrane and acrosome integrity, high mitochondrial membrane potential, viability, and oxidative stress. The AKAP4 localization was determined by immunofluorescence, and intensity (X103 arbitrary units) was measured in 300 sperm/sample. Cluster analysis examined categorical effects of AKAP4 intensity (low, medium, and high), and correlations assessed continuous effects. Results Ninety ejaculates from 18 goats (10 Boer and 8 Anglo-Nubian) were analyzed. A-kinase anchoring protein 4 localized to the acrosomal region. Low AKAP4 fluorescence intensity was linked to reduced total motility (45.3%; 95% CI, 41.1 to 49.5; partial 112 = 0.128), progressive motility (14.3%; 95% CI, 12.5 to 16.1; partial 112 = 0.131), and average path velocity, straight-line velocity, and beat cross frequency (partial 112 = 0.105 to 0.114), while curvilinear velocity showed a moderate effect (partial 112 = 0.060). The amplitude of lateral head displacement, straightness, linearity, wobble, plasma membrane, and acrosome integrity, viability, and reactive oxygen species were similar across groups (partial 112 = 0.002 to 0.042). Mitochondrial membrane potential was lower in the low group (52.3%; 95% CI, 48.0 to 56.6; partial 112 = 0.071) than in the medium group (62.2%; 95% CI, 58.3 to 66.1). No correlations were observed between AKAP4 and sperm parameters. Conclusions A-kinase anchoring protein 4 intensity in frozen-thawed goat sperm affects energy metabolism and motility in a nonlinear, threshold-dependent manner, serving as a categorical sperm quality indicator. Clinical Relevance A-kinase anchoring protein 4 may serve as a biomarker for goat semen quality, particularly motility.