The pathogenesis of the disorder is poorly understood, and no approved drug treatment is currently available...

Delayed ejaculation affects around 3% of men, and can be primary (lifelong) or secondary (acquired). The pathogenesis of the disorder is poorly understood, and no approved drug treatment is currently available, despite the negative effects of delayed ejaculation on the patient and his partner, and potential impact on their ability to conceive.

A recent study published in the Journal of Sexual Medicine presents evidence for an improvement in ejaculation after treatment with low doses of the endocannabinoid anandamide (AEA) in sexually sluggish (SLG) male rats, which offer a natural animal model for men with lifelong delayed ejaculation. 110 male SLG rats—defined as requiring more than 20 min to ejaculate after first intromission, or no ejaculation within 30 min—were used in the study, and compared with males with optimal sexual behaviour as a positive control. Male rats were treated with varying doses of AEA (0.1–3 mg/kg by intraperitoneal injection), as well as the CB1 receptor antagonist AM251, alone or in combination. They were then introduced into cylindrical arenas, and a receptive female introduced 5 min later. Sexual behaviours, including intromission latency, number of mounts and intromissions preceding ejaculation, ejaculatory latency and interintromission interval, were recorded for 60 min.

Intermediate doses (0.3 mg/kg and 1 mg/kg) of AEA signficiantly reduced number of intromissions and ejaculatory latency in SLG rats, compared with vehicle treatment. Further sexual behaviour trials of these rats 7 days later showed that the effect of AEA was short-lived, and had disappeared by this time point, with intromissions and ejaculatory latency times returning to baseline. AM251 treatment did not affect sexual behaviour parameters in SLG rats, but pretreatment with AM215 before AEA administration blocked the effect of AEA on the sexual parameters observed, suggesting a role for CB1 receptors in the effect of AEA on sexual behaviour.

The effects of AEA on intromission number and ejaculatory latency in SLG rats were isolated, with no effects observed on other sexual behaviours. The site of action for AEA in this mechanism is unknown, but AEA is able to cross the blood–brain barrier, so could be central or within the spinal cord. The specificity of its effect, coupled with the low doses required for action, suggests that AEA could offer hope for men with primary delayed ejaculation, and that it warrants further clinical investigation.