ERECTOGENIC AND SPERMIOLOGIC EFFECTS OF STEM BARK EXTRACTS OF Nauclea Latifolia (Smith) IN RABBITS

Abstract

Erectile dysfunction is a sexual disorder to which both natural and synthetic remedies are being sought. Extract of Nauclea latifola (NL) has been used in folkloric medicine to ameliorate this sexual disorder; however there is paucity of scientific information on its erectogenic and spermiologic effects. This study was designed to investigate the effects of NL on erection and reproductive parameters in male rabbits. The plant was collected and authenticated at Forestry Research Institute of Nigeria(FHI.109602). Ethanol and Acetone Extracts of NL (EENL and AENL) were prepared from pulverized stem bark of NL. Forty male rabbits (Oryctolagus cunniculus) weighing 1.8-2.2 kg were divided into two groups. One group was orally treated with distilled water (control), EENL (100 and 200 mg/kg) and 0.5 mg/kg Sildenafil citrate (Sc) for five days. The second group received similar treatment for 28 days. In another experiment, forty male rabbits (1.8-2.2 kg) were divided into two groups and treated with AENL as outlined in the first experiment. They were paired with warmed females and observed for; Mount Frequency (MF), lntromission Frequency (IF), Mount Latency (ML), intromission Latency (IL) and Ejaculatory Latency (EL) on days 1, 3, 5 and 28 inside a mating arena monitored with digital camera. After 28 days, spermatozoa motility, count and morphology were determined by microscopy. Luteinizing and Follicle Stimulating Hormones (LH and FSH), testosterone and prolactin were measured by enzyme immunoassay technique, Aspartate and Alanine Aminotransferases (AST and ALT) and Alkaline Phosphatase (ALP) were measured spectrophotometrically. Testicular tissues were stained with haematoxylin and cosin and examined under light microscope. Column and thin layer chromatography were used for fractionation of EENL. Twenty-five male rabbits (1.8-2.2 kg) assigned into 5 groups and treated with distilled water (control), fraction 1 (10 ppm), fraction 2 (10 ppm), fraction 3 (10 ppm) and 0.5 mg/kg SC for a day. Nitric Oxide (NO) concentration was determined from corporal homogenates by spectrophotometry. Data were analysed using Student's t-test and ANOVA at p=0.05. The EENL, AENL and SC significantly increasd MF, IF and EL while ML and IL decreased during five and 28 days of treatment. The EENL (200 mg/kg) significantly increased AST-33±1.3, ALT-39.0±0.3 and ALP-106.8±0.3 when compared with the control 24.2±1.5, 30.0±0.6 and 96.2±0.5 IU/L respectively while the same parameters were significantly reduced at 100 mg/kg. The EENL (100 mg/kg) significantly increased spermatozoa count (90.5±0.1), motility (88.5±0.1), LH (36.6±0.5mIU/mL), FSH (11.2±0.3 mIU/mL) and testosterone (1.6±0.1 ng/mol) relative to the control (76.0±0.1, 82.7±0.1, 27.2 mIU/mL, 5.0±0.6 mIU/mL, and 1.3±0.4 ng/mol) respectively. Spermatozoa morphological abnormalities were significantly increased in 200 mg/kg EENL (14.5±1.3) relative to the control (10.4±0.9). Testes of rabbits treated with EENL (200 mg/kg) showed necrosis and distortion of testicular cytoarchitecture while EENL (100 mg/kg) and SC showed no lesion. The fractions and SC significantly increased corporal NO concentration, MF, IF and EL. Ethanol extract of Nauclea latifolia at 100 mg/kg and its fractions possess erectogenic properties via increases in nitric oxide concentration and exerted moderate effects on male reproductive parameters.