Influence of Eurycoma longifolia on the copulatory activity of sexually sluggish and impotent male rats

Abstract

Aim of the study: The root of Eurycoma longifolia Jack, native to South East Asia, has long been used as a male aphrodisiac remedy to treat sexual disorders.

In the study we evaluated the influence of Eurycoma longifolia Jack on sexual behavior (including both motivation and copulatory performance) of sexually sluggish and impotent male rats.

Materials and methods: The root powder of the plant was orally administered to adult Sprague–Dawley male rats, classified as sexually sluggish or impotent taking in account their behavior in pre-experimental tests. Groups of 8 animals each were submitted to three different types of treatment: (1) acute at 3 dose levels (250, 500 and 1000 mg/kg); (2) subacute (daily for 6 days) at the dose of 500 mg/kg and (3) subchronic (daily for 12 days) at the same dose (500 mg/kg). Mount, intromission and ejaculation latencies and post-ejaculatory interval were recorded during the mating test in order to evaluate sexual performance. In addition the partner preference test was used to assess sexual motivation. Testosterone serum levels were measured in subacutely treated rats and compared with the values of controls receiving vehicle.

Results: Concerning the copulatory activity of sexually sluggish rats, both acute (dosed at 500 and 1000 mg/kg) and subacute treatments with the root powder significantly reduced ejaculation latencies, increasing also the percentage of mounting and ejaculating animals; in addition the subacute administration reduced post-ejaculatory interval. In impotent rats both subacute and subchronic treatments increased the percentage of mounting and ejaculating rats. The motivational behavior of sluggish rats during the partner preference test was not affected by the treatments. Testosterone serum levels were increased in rats subacutely treated in comparison with controls.

Conclusion: Eurycoma longifolia root improved sexual performance but not motivation in sluggish rats after acute or subacute administration. The effect could be mainly ascribed to increased testosterone levels.