Kusemiju T O, Osinubi A A, Noronha C C, Okanlawon A O
Department of Anatomy, College of Medicine, University of Lagos, Idi-Araba, Lagos, Nigeria.
Nig Q J Hosp Med. 2010 Jul-Sep;20(3):133-7.
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.
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.
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.
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.
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.
男性控制生育的选择通常很少，而且这些选择远不能令人满意。迫切需要开展研究以开发更多的男性避孕方法。
本研究的总体目标是确定给予斯普拉格-道利大鼠每日单次剂量100 mg/kg番木瓜树皮水提取物后，其睾丸的组织学反应，并研究这些反应是否可逆。
本实验使用60只成熟（6 - 8周龄）雄性斯普拉格-道利大鼠，分为2组，每组数量相等。第1组大鼠连续4周和8周每日喂食100 mg/kg提取物，第2组大鼠作为对照。将大鼠的每个附睾尾取出，切开并对挤出的液体进行精子活力和计数检测。摘取睾丸并进行处理，在光学显微镜下进行组织学检查。进行植物化学分析以确定提取物中的主要成分，同时测定半数致死量（LD50）以指导提取物的给药剂量。处死前，让一组动物有8周的恢复期。
结果显示，500 mg/kg（LD50）番木瓜树皮提取物产生毒性迹象，50%的大鼠死亡。100 mg/kg剂量的提取物引起组织学变化，从生精小管扭曲到生精小管完全破坏/退化。此外，提取物处理组大鼠的睾丸间质显示结构紊乱和细胞减少。提取物还导致精子计数和活力显著（p < 0.05）降低。8周恢复期后，这些抗生精作用没有明显逆转。
番木瓜树皮水提取物对生精小管和睾丸间质均有有害影响，作为一种潜在的男性避孕剂值得进一步研究。
