Protective Effects of Aqueous Extract of Carica papaya Leaf on the Liver of Streptozotocin (STZ)-Induced Diabetic Adult Wistar Rats

Carica papaya Linn. (Family: Caricaceae) is a perennial, herbaceous plant used traditionally among the Yoruba tribe of Nigeria for the treatment of various human and veterinary diseases including malaria, hypertension, diabetes mellitus, hypercholesterolemia, Jaundice, intestinal helminthiasis. Therefore, this study was designed to assess some of the effects of aqueous extract of C. papaya leaf on the liver of Streptozotocin(STZ)-induced diabetic adult wistar rats.

Experimental diabetes was induced by intraperitoneal injection of 60 mg/kg STZ freshly dissolved in 0.1M Sodium Citrate at PH buffer at 4.5. Hyperglycemia was confirmed four days after injection by measuring the tail vein blood glucose level with an Accu-Check Sensor Comfort Glucometer (Roche, Mexico City). Only the animals with fasting blood glucose levels <200 mg/dl were considered diabetic. A total number of 48 adult wistar rats weighing between 100 -250 g of both sexes were used for this study. The rats were acclimatized to the experimental room having temperature of 25°C. Four groups were used for this study, group A served as the control which were fed with feeds and water ad libitum daily for six weeks and group B,C &D were induced with 60 mg/kg of STZ after which were diagnosed of diabetes after 4 days of induction. Group B served as the diabetic control group and were fed with only feed and water ad libitum daily for six weeks whereas, group C and D were treated with different doses of C. papaya extract (1.5 and 3.0 mg/100 mL) as drinking water daily for six week and were sacrificed by cervical dislocation and the liver was removed and weighed before fixing in 10% formol saline for histological procedures.

The result showed a significant decrease in body weight of diabetic -induced rats (P<0.05) while the body weights increased significantly (P<0.05) in diabetic induced rats treated with 1.5 and 3.0 g/100 mL of the aqueous extract of C. Papaya leaves when the initial and final weights of the rats were compared at the end of treatment. However, the liver weights increased significantly (P<0.05) in diabetic induced rats when compared with the diabetic rats treated with extract. The aqueous extract of C. papaya (1.5 and 3.0 g/100 mL) significantly decreased (P<0.05) blood glucose levels in diabetic treated rats. There was significant increase in serum biomarker enzymes: ALT, AST and ALP in diabetic rats (Group B) at P<0.05 when compared with control rats (Group A). Conversely, biomarker hepatic enzymes: ALT, AST and ALP decreased significantly (P<0.05) in diabetic rats treated with 1.5 and 3.0 g/100 mL aqueous extract of C. papaya leaves when compared with both Group A and Group B. The histological section of the liver of diabetic rats treated with 3.0 g/100 mL aqueous extract of C. papaya leaves showed improvement in hepatic histo-architecture as the extract ameliorated hepatic morphological disruption occasioned by induced diabetes in wistar rats.

This study concluded that aqueous extract of C. papaya leaf ameliorated hepatic induced damage in the liver of Streptozotocin(STZ)-induced diabetic adult wistar rats.