Mondia whitei (Periplocaceae) prevents and Guibourtia tessmannii (Caesalpiniaceae) facilitates fictive ejaculation in spinal male rats

BACKGROUND: Mondia whitei and Guibourtia tessmannii are used in Cameroon traditional medicine as aphrodisiacs. The present study was undertaken to evaluate the pro-ejaculatory effects of the aqueous and organic solvent extracts of these plants in spinal male rats. METHODS: In spinal cord transected and urethane-anesthetized rats, two electrodes where inserted into the bulbospongiosus muscles and the ejaculatory motor pattern was recorded on a polygraph after urethral and penile stimulations, intravenous injection of saline (0.1 ml/100 g), dopamine (0.1 μM/kg), aqueous and organic solvent plant extracts (20 mg/kg). RESULTS: In all spinal rats, urethral and penile stimulations always induced the ejaculatory motor pattern. Aqueous or hexane extract of Mondia whitei (20 mg/kg) prevented the expression of the ejaculatory motor pattern. The pro-ejaculatory effects of dopamine (0.1 μM/kg) were not abolished in spinal rats pre-treated with Mondia whitei extracts. Aqueous and methanolic stem bark extracts of Guibourtia tessmannii (20 mg/kg) induced fictive ejaculation characterized by rhythmic contractions of the bulbospongiosus muscles followed sometimes with expulsion of seminal plugs. In rats pre-treated with haloperidol (0.26 μM/kg), no ejaculatory motor pattern was recorded after intravenous injection of Guibourtia tessmannii extracts (20 mg/kg). CONCLUSION: These results show that Mondia whitei possesses preventive effects on the expression of fictive ejaculation in spinal male rats, which is not mediated through dopaminergic pathway; on the contrary, the pro-ejaculatory activities of Guibourtia tessmannii require the integrity of dopaminergic system to exert its effects. The present findings further justify the ethno-medicinal claims of Mondia whitei and Guibourtia tessmannii.