This study was undertaken to evaluate the effects of Aframomum melegueta on male rat ejaculation using in/ex copula techniques. For the in copula experiment, rats were orally treated with aqueous or methanolic extract (20 and 100 mg/kg) of A. melegueta for 14 days. Each rat was mated with a primed receptive female on days 0, 7 and 14 of treatment, and the ejaculatory latency and post-ejaculatory interval were measured. In the ex copula experiment, the electromyography of the bulbospongiosus muscles and intraseminal pressure were recorded in spinal rats after mechanical (urethral and penile) and pharmacological stimulations (intravenous injection of dopamine (5 mg/kg) and, aqueous or methanolic extract of A. melegueta, 2.5; 5; 10 and 20 mg/kg). Furthermore, the effect of dopamine on fictive ejaculation was monitored in rats orally pre-treated with A. melegueta extracts (20 and 100 mg/kg) for 7 or 14 days. Treatment with the aqueous or methanolic extract of A. melegueta significantly decreased the ejaculatory latency (p < .05) and post-ejaculatory interval (p < .01) after 14 days. In spinal rats, mechanical or pharmacological stimulations triggered fictive ejaculation. In animals orally pre-treated with A. melegueta extracts, the pro-ejaculatory effect of dopamine was more expressed. Present findings show that A. melegueta possesses pro-ejaculatory effects.

Context:Guibourtia tessmannii (Caesalpiniaceae) is a plant traditionally used as aphrodisiac. We previously reported the pro-ejaculatory effects of the aqueous and methanol extracts of G. tesmannii in spinal male rat. However, the mechanism underlying such effects has not been elucidated.Objective: This study characterizes the dopaminergic sub-type receptors involved in G. tesmannii-induced ejaculation in male Wistar rat.Materials and methods: Urethane-anesthetized spinal male rats were intravenously treated with saline solution (1 mL/kg, control); dopamine (0.1 μmol/kg, reference); aqueous or methanol extracts of G. tesmannii (20 mg/kg) in the absence or presence of haloperidol (0.26 μmol/kg), a nonspecific dopaminergic receptor antagonist, Sch23390 (0.26 μmol/kg), a specific D1-like receptor antagonist or, sulpiride (0.26 μmol/kg), a specific D2-like receptor antagonist. Electromyography of the bulbospongiosus muscles and intraseminal pressure were recorded after urethral, penile and drug stimulations.Results: Urethral and penile stimulations, intravenous injection of dopamine or, aqueous and methanol extracts of G. tesmannii always triggered the expression of rhythmic contraction of the bulbospongiosus muscles with an average mean of 3.33 ± 0.43; 7.83 ± 0.85; 9.80 ± 0.86; 0.83 ± 0.54 and 2.67 ± 0.95 contractions, respectively. The intraseminal pressure was more expressed after urethral and penile stimulations (15.66 ± 1.58 and 13.60 ± 2.40 mmHg, respectively). In rats pretreated with haloperidol, Sch23390 or sulpiride, no ejaculation was recorded after intravenous injection of G. tesmannii extracts or dopamine.Discussion and conclusion:Guibourtia tesmannii-induced ejaculation requires the integrity of D1 and D2-like receptors. These findings further justify the ethno-medicinal claims of G. tesmannii as an aphrodisiac.

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