The aim of this study was to investigate the effects of Bersama engleriana and its potential mechanism on fictive ejaculation in spinal male rats. The electromyographic activities of the bulbospongiosus muscles were recorded in spinal cord transected and urethane-anesthetized rats treated intravenously with aqueous (100 mg kg^-1) and methanolic (100 mg kg-1) extracts from the dried leaves of B. engleriana in the absence and presence of dopamine (0.1 mol kg^-1) or oxytocin (0.5 UI kg^-1). Mechanical stimulations of the urethra were also carried out 5 min after the sequential treatments. A single intravenous administration of aqueous (100 mg kg-1) and methanolic (100 mg kg-1) extracts of B. engleriana did not activate fictive ejaculation. The electromyography recorded after the application of the plant extract was similar to that obtained after intravenous saline injection (200 Gl min-1) with no contraction of the bulbospongiosus muscles. Dopamine (0.1 mol kg-1) and oxytocin (0.5 UI kg^-1) induced rapid rhythmic contractions (P < 0.001) of the bulbospongiosus muscles accompanied by penile erection and sometimes with expulsion of the seminal plugs. Pre-treatment of rats with the two plant extracts completely abolished the occurrence of ejaculation induced by dopamine (0.1 mol kg-1) and oxytocin (0.5 UI kg^-1). Mechanical stimulation of the urethra carried out 5 min after the sequential treatments always induced penile movements and erections. The inhibitory effect of B. engleriana extracts on the expression of fictive ejaculation in spinal male rat is mediated through dopaminergic and oxytocinergic pathways. This prolonged ejaculatory latency caused by B. engleriana could support its potential use in patients with rapid ejaculation.

Keywords: Bersama engleriana, dopamine, ejaculation, inhibition, oxytocin, spinal rat

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