Efficacy of In Vitro Addition of Low-Dose Arachidonic Acid in Improving the Sperm Motility of Obese Infertile Men With Asthenozoospermia

Abstract

This study aimed to investigate the impact of in vitro low-dose arachidonic acid (AA) addition on enhancing sperm motility in obese infertile men with asthenozoospermia. Semen samples were collected from 115 infertile men, categorized into two BMI groups: 18.5–23.9 kg/m² and ≥ 28 kg/m², with all subjects demonstrating a sperm concentration of ≥ 15 × 10⁶/mL. These were further divided into four cohorts based on the percentage of sperm progressive motility (PR): control-normal, control-asthenozoospermia, obese-normal, and obese-asthenozoospermia. Normal PR was classified as ≥ 32%, while asthenozoospermia was characterized by PR < 32%. Metabolomic analysis was employed to quantify seminal plasma metabolites, with differential metabolites identified through statistical evaluation. Additionally, semen samples from 10 infertile men—5 with a body mass index (BMI) of 18.5–23.9 kg/m² and 5 with a BMI of ≥ 28 kg/m²—underwent further scrutiny. Post-initial semen analysis, 1 mL of semen stock was extracted, treated with 100 pg of AA, incubated at 37°C for 1 h, and reanalyzed to determine the impact on sperm motility. Additionally, 16 Sprague Dawley (SD) rats were split into two groups: control and obese. The control group received a standard diet, while the obese group was subjected to a 45% high-fat diet. After 3 months, the rats were euthanized via cervical dislocation, and their prostate and seminal vesicles were collected for metabolite analysis. A comprehensive analysis of 4635 metabolites in seminal plasma revealed that bile acid secretion emerged as the most significant pathway within the organic systems category, accounting for 0.6% of the total metabolites. Meanwhile, metabolic pathways overwhelmingly dominated the metabolism category, with AA metabolism contributing 4.62%. Notably, 29 metabolites were associated with bile acid secretion, yet no significant differences were observed between the PR ≥ 32% and < 32% groups. In contrast, 214 metabolites were linked to AA metabolism, exhibiting a predominantly downregulated trend, with no upregulated metabolites identified. Within the seminal plasma AA metabolic network, indicators showed a positive association with the induced acrosome reaction, seminal plasma Ca²⁺ levels, PR, and the proportion of grade A sperm (rapid forward motion, speed ≥ 25 μm/s). Additionally, secretory phospholipase A2 (sPLA2), AA, and cyclooxygenase-1 (COX1) levels demonstrated a negative correlation with anthropometric measurement parameters in the Control-SP group, though this correlation did not reach statistical significance, while a positive correlation was evident in the Obesity-SP group. The concentrations of sPLA2, AA, and COX1 within the AA metabolic network exhibited the following trend: Control-SP-N > Obesity-SP-N > Control-SP-A > Obesity-SP-A. In vitro addition of 100 pg AA significantly enhanced the proportion of grade B sperm (slow-moving, speed < 25 μm/s) while reducing grade C sperm (non-forward-moving) in individuals with a BMI of 18.5–23.9 kg/m² (p < 0.05). In contrast, for those with a BMI ≥ 28 kg/m², a marked increase in grade A and grade B sperm and a corresponding reduction in grade C sperm was noted (p < 0.05). Human seminal plasma levels of sPLA2, AA, and COX1 were significantly elevated in the Control-SP group compared to the Obesity-SP group (p < 0.05). However, sPLA2, AA, and COX1 levels in the prostate and seminal vesicle of SD rats did not differ significantly between the Control and Obesity groups (p > 0.05). Distinct metabolic profiles in seminal plasma of infertile men, stratified by BMI, exhibit significant impacts on sperm quality. Low-dose AA, under physiological conditions, maintains sperm integrity and augments fertilization potential. In vitro administration of low-dose AA demonstrates superior effectiveness in enhancing sperm parameters, particularly in obese individuals with asthenozoospermia.