Changes in human spermatozoa associated with high-dose marihuana smoking

We have shown that 4 wk of high-dose marihuana use (8-20 cigarettes/d) in 1 6 healthy, chronic marihuana smokers was associated with a significant decl ine in sperm concentration and total sperm count during the fifth and sixth weeks after the first exposure. This was preceded by a decrease in sperm m otility and accompanied by a reduction in the number of sperm with normal m orphology. In 12 of IG subjects, a highly significant decrease was noted, w hich was sustained until the end of the study in Ii subjects. No evidence was obtained suggesting a hormonal mechanism far observed effec ts. The most likely explanation is a direct cannabinoid effect on the germi nal epithelium during spermiogenesis. Loss of motility response to cyclic A MP and a phosphodiesterase inhibitor, theophylline, in two subjects indicat es that the sperm produced following cannabinoid exposure may also have str uctural or biochemical defects in sperm function. The improvement in sperm motility following cessation of chronic smoking raises some optimism concer ning the reversibility of the abnormalities and, if confirmed in additional subjects, gives further credence to the causal relationship between acute marihuana exposure and the abnormalities subsequently observed. No conclusi on can be reached regarding the possibility of adverse effects of acute or chronic marihuana use upon human reproduction. On the other hand, it is ess ential that further studies be undertaken that will examine this possibilit y.