Effects of Annona Muricata (Linn) on the Pancreatic Islet Cells of Experimentally-Induced Diabetic Rattus Norvegicus (Berkenhout, 1769)
This study assessed the effects of methanolic extract of Annona muricata (Annonaceae) on the body weight, blood glucose level, serum lipid profiles and morphology and morphometry of the cells of the pancreatic islets of Langerhans of experimentally-induced diabetic Wistar rats. This was with a view to determining the anti-diabetic activities of Annona muricata. Thirty adult Rattus norvegicus were randomly assigned into three groups (A, B and C) of ten rats each. Group A was the control, Group B was untreated diabetic group and group C was A. muricata-treated group. The body weight, blood glucose level and serum lipid profiles were monitored in all the animals four weeks before the commencement of the experiment and throughout the experimental period. Diabetes mellitus was induced in groups B and C by a single intra-peritoneal injection of 80 mg/kg streptozotocin (Sigma, USA) dissolved in 0.1 M citrate buffer. The control group was intra-peritoneally injected with equivalent volume of citrate buffer and all the animals were monitored for another four week period. Daily intra-peritoneal injection of 100 mg/kg A. muricata was administered to group C rats for two weeks and the animals were monitored for another two week period. At the end of the experiment, the rats were sacrificed by cervical dislocation and the pancreas of each animal was removed, weighed and fixed by immersion in Bouins fluid. The tissues were processed for paraffin embedding and sections of 6μm thickness were produced and stained with hematoxylin and eosin, Gomori Aldehyde fuchsin and Gomori chrome alum hematoxylin phloxine to demonstrate β-cells of the pancreatic islets. The data obtained were analyzed with descriptive and inferential statistics. The result showed a significant increase (t = -16.90; df = 9; p < 0.05) in the body weights of A. muricata-treated group (197 ± 5.62 g) when compared to that of the untreated diabetic group (173.29 ±5.13 g) and a significant decrease (t = 6.94; df = 9; p < 0.05) in the blood glucose concentration of A.muricata - treated group (4.22 + 0.151 mmol/L) when compared to that of the untreated diabetic group (21.64 + 2.229 mmol/L). The result of the serum lipid analysis showed a significant reduction in the serum total cholesterol (t = 7.91; df = 9; p < 0.05), triglyceride (t = 8.36; df = 9; p < 0.05) and low-density lipoprotein cholesterol (t = 25.91; df = 9; p < 0.05) of A. muricata-treated group (1.649 ± 0.010 mmol/L, 0.972 ± 0.024 mmol/L and 0.392 ± 0.005 mmol/L respectively) when compared to that of the untreated diabetic group (2.044 ± 0.048 mmol/L, 1.650 ± 0.079 mmol/L and 0.883 ± 0.002 mmol/L respectively). However, there was a significant increase in the serum high-density lipoprotein cholesterol (t = -30.30; df = p < 0.05) of A. muricata-treated group (0.807 ± 0.012mmol/L) when compared to that of the untreated diabetic group of rats (0.411 ± 0.007 mmol/L). Histopathological and morphometric examination of the stained pancreatic sections showed a significant increase in the number (t = -8.40; df = 9; p < 0.05), diameter (t = -2.20; df = 49; p < 0.05) and volume (t = 4.49; df = 49; p < 0.05) of the β-cells of pancreatic islets of A. muricata-treated group (5.67 ± 0.184 N/1000μm2, 5.38 ± 0.093 μm and 85.12 ± 4.24 μm3 respectively) when compared to that of the untreated diabetic group of rats (2.85 ± 0.361 N/1000μm2, 2.85 ± 0.362 μm and 69.56 ± 5.216 μm3 respectively) The study demonstrated that A. muricata possesses anti-hyperglycemic and antihyperlipidemic activities as well as the ability to regenerate destroyed β-cells of pancreatic islets of Langerhans of streptozotocin-induced diabetic rats.