Effect of aqueous extract of the bark of Carica papaya on testicular histology in Sprague-Dawley rats
Background: Males generally have few options for controlling their fertility and these options are far from being satisfactory. There is a great need for research to develop more contraceptive modalities for males.
Objective: The overall aim of this research was to determine the histological responses of the testes of Sprague-Dawley rats to aqueous extract of bark of Carica papaya using a single daily dose of 100 mg/kg and also to investigate if these responses are reversible or not.
Materials and Methods: Sixty mature (6-8 weeks old) male Sprague-Dawley rats, divided into 2 equal groups, were used for this experiment. Group 1 rats were fed with 100 mg/kg/day of the extract for 4 and 8 weeks, while group 2 rats served as the control subjects. Each cauda epididymis of the rats was exteriorized, incised and sperm motility and count conducted on expressed fluid. The testes were harvested and processed for histological examination under light microscope. Phytochemical analysis was done to ascertain the main constituents in the extract, while the LD50 was conducted to guide in the dose of administration of the extract. A subgroup of the animals was allowed a recovery period of 8 weeks before sacrifice.
Results: The results showed that 500 mg/kg (LD50) of the extract of bark of Carica papaya produced signs of toxicity with mortality of 50% of the rats. The extract at a dose of 100 mg/kg caused histological changes ranging from seminiferous tubular distortion to outright destruction/degeneration of the seminiferous tubules. In addition, the testicular interstitia of extract-treated rats showed disorganization and hypocellularity. The extract also caused a significant (p<0.05) reduction in both sperm count and motility. There was no significant reversal of these antispermatogenic effects following a recovery period of 8 weeks.
Conclusion: Aqueous extract of the bark of Carica papaya has deleterious effects on both the seminiferous tubules and testicular interstitium and deserves to be further investigated as a potential male contraceptive agent.
Keywords: Carica papaya, testis, seminiferous tubules