Effects of delta-9-tetrahydrocannabinol, the primary psychoactive cannabinoid in marijuana, on human sperm function in vitro.

Objective: To investigate effects of delta-9-tetrahydrocannabinol (THC) on human sperm function in vitro.

Design: Laboratory analysis of sperm motility after exposure to THC using computer-assisted semen analysis and acrosome reaction by fluoroscein isothiocyanate-labeled peanut agglutinin staining.

Setting: An assisted reproductive technology unit.

Patient(s): Seventy-eight male patients.

Intervention(s): Sperm were divided into 90% (the best fertilizing potential used in assisted conception) and 45% (the poorer subpopulation) fractions by density centrifugation and incubated with THC at concentrations equivalent to therapeutic (0.032 microM) and recreational (0.32 and 4.8 microM) plasma levels at 37 degrees C for 3 h.

Main Outcome Measure(s): Sperm motility and spontaneous and induced acrosome reactions.

Result(s): Percentage progressive motility was decreased dose dependently in the 90% fraction (by 2%-21%; P<.05; P<.001). The 45% fraction showed a greater decrease in percentage progressive motility (by 28% at 0.032 microM; 56% at 4.8 microM; P=.004 and P=.01 res). Straight line velocity and the average path velocity also were reduced (by 10%, in the 90% LAYER) in both fractions. Spontaneous acrosome reactions were reduced in the 90% (17% at 0.032 microM, 35% at 4.8 microM P=.004 and P<.001 resp) and more markedly in the 45% fractions (17%-35%; P<.001). When the acrosome reaction was artificially induced (90% fraction) by A23187, THC (4.8 microM) resulted in a 57% inhibition (P<.001).

Conclusion(s): The use of THC as a recreational drug may adversely affect male fertility.