Effect of castration and testosterone administration on the analgesic efficacies of methanolic extract of Annona Senegalensis and Piroxicam in Wistar rats.

Introduction: Analgesic potency of Annona senegalensis (crude stem-bark methanolic extract) and piroxicam on castrated and testosterone-treated male Wistar rats were evaluated. Methods: Twenty-five (25) mature male Wistar rats with average body weight of 184 ± 4.1 g were randomly allocated into five groups of five (n = 5) rats each. Groups I and II were non-castrated (NC) and treated as follows: group I (NC + Annona senegalensis {AS; 910mg/kg}), while group II (NC + piroxicam {PRX; 10mg//kg}). Rats in groups III, IV and V were castrated and treated as follows: castrated (CS) + distilled water {DW; 0.5ml/rat}); (CS + Annona senegalensis {AS; 910mg/kg}); (CS + AS + Testosterone 400µg/rat) respectively. The latent period of pain sensation (analgesic time) was determined using hot plate thermal method, and recorded in seconds. Results: Latent period of analgesia in rats was recorded at 0, 30-, 60-, 90-, and 120-mins post treatment with A. Senegalensis and piroxicam. The serum concentration of testosterone post experiment showed higher levels in group II rats (NC+PRX; {4.3ng/ml}) while group III and V rats had the lowest concentration (CS+DW; CS+AS+TES {2.9ng/ml}) and group IV rats all died after the experiment (CS+AS). The findings of the study indicated that the analgesia effect of A. senegalensis is higher than the piroxicam-induced analgesia (3.8±1.2 vs 1.0±0.0sec, 2.0±1.4 vs 1.0±0.0sec) at 30mins and 60mins in groups I and II respectively. Significance: Castration and testosterone replacement did not affect the Analgesic effect of Annona senegalensis while castration enhanced the latent period of thermal pain sensation. [ABSTRACT FROM AUTHOR]