High concentration of dopamine treatment may induce acceleration of human sperm motility

Purpose In humans, catecholamines (including dopamine) have been identified in semen and fallopian tubes, while dopamine D2 receptors (D2DR) are found in the sperm midpiece region. How dopamine dose affects human sperm function and whether dopamine treatment is useful in assisted reproductive technology is unclear. Methods Sperm samples were obtained from patients with normal semen parameters undergoing fertility treatment. We investigated the effects of dopamine treatment on tyrosine phosphorylation and sperm motility. Sperm motility was analyzed using the computer-assisted sperm analysis (CASA) system. Results This study revealed that various dopamine concentrations (0.1-100 mu M) did not increase sperm tyrosine phosphorylation. Progressive motility increased substantially when treated with high concentrations of dopamine (10 and 100 mu M) and was blocked by raclopride (a D2DR antagonist). After 24-h sperm culture, the addition of 10 mu M dopamine significantly increased curvilinear velocity and amplitude of lateral head displacement, which are indicators of hyperactivation. Conclusion Dopamine did not affect tyrosine phosphorylation, but increased sperm motility. High concentrations of dopamine were more effective to accelerate sperm motility in cases where sperm motile capacity was low.