Effects of Mucuna prurita seeds on sexual behaviour of male rats

Abstract

In Sri Lanka, in the Ayurvedic medicine, seeds of Mucuna prurita (both with seed coats and without seed coats) are recommended to be used as an aphrodisiac. However, the validity of this claim is not established. The aim of this study was to test the aphrodisiac potential of M. prurita seeds using a powdered suspension m X% methyl cellulose. Male rats were treated orally with different doses of whole powdered seed suspension (WPSS) [1,500 mg/kg in = 12) once a day; 1,500 mg/kg (« = 12) twice a day or 1,500 mg/kg (n = 12) three times a day] or decoated powdered seed suspension (DPSS) [1,500 mg/kg (n = 12) twice a day and 1,500 mg/kg (n = 6) three times a day] or vehicle. The male sexual behaviour of these rats was monitored 2 h later. The DPSS had no effect whatsoever on male sexual behaviour. In contrast, mid and high doses of the WPSS caused a marked reduction in pre-coital sexual behaviour (in terms of chasing, genital grooming, anogenital sniffing), failure of rats to mount, intromit or ejaculate and prolongations of latencies to mount and intromit. In addition, the mid dose of WPSS caused a prolongation of intercopulatory interval. These impairments of sexual behaviour were reversible. The mid dose also had marked sedative (in terms of impairment of numbers of rear, head dips, locomotory activity) and analgesic (marked prolongation of reaction time in both tail flick and hot plate test) effects. This dose inhibited neither muscle strength (assessed by a bar holding test) nor muscle co-ordination (Bridge test). We conclude that the WPSS of M. prurita seeds inhibited libido, sexual arousal/motivation and penile tactile sensitivity without disrupting sexual performance.