The CB₂ cannabinoid receptor regulates human sperm cell motility

Objective

To analyze the expression and distribution of cannabinoid receptors in human sperm cells and evaluate the effects of activation of receptors by specific agonists and antagonists, with a special emphasis on the CB₂ receptor.

Design

We performed expression assays for CB₁ and CB₂ by reverse transcriptase PCR, Western blot, and immunofluorescence techniques in spermatozoa and performed motility analysis after incubation of semen samples with cannabinoid agonists and CB₂ antagonist SR144528.

Setting

Academic research laboratory.

Patient(s)

Semen from 50 normozoospermic, healthy human donors.

Intervention(s)

Spermatozoa isolated from semen by two consecutive swim-ups were used for all techniques.

Main Outcome Measure(s)

Reverse transcriptase PCR amplification gels, immunoblots, indirect immunofluorescence antibody assays, and percentage of motile sperm.

Result(s)

We have verified the presence of CB₁ and CB₂ receptors in human spermatozoa. The distribution of both of these receptors was distinct. Incubation with selective cannabinoid receptor agonists induced a significant reduction in the proportion of rapidly progressive motile spermatozoa, and whereas the CB₁ agonist increased the proportion of immobile sperm cells, the CB₂ receptor agonist increased the slow/sluggish progressive sperm cell population. The effect of the CB₂ agonist was antagonized by the CB₂-specific antagonist.

Conclusion(s)

The functional CB₂ cannabinoid receptor is present in human spermatozoa and regulates the sperm motility in a more distinct manner than CB₁.

Key Words: Cannabinoids, receptor activation, human sperm motility