Suitability of the Neonatal Streptozotocin Diabetes Model and Folklore Therapeutic use of Low-Dose Neem Leaf Extract to Treat Hyperglycemia Associated with Type 2 Diabetes Mellitus

Abstract

Neem leaf has been used in folklore medicine to combat diabetes mellitus and other ailments. Difficulty finding suitable type 2 diabetes mellitus (T2DM) models led to the exploration of the neonatal streptozotocin (nSTZ) model to investigate the impact of low-dose neem leaf extract (NLE) on T2DM-associated hyperglycemia. Following ethical approval, two-and three-day-old neonatal rat pups (n=66) received 60 mg/kg STZ intraperitoneally while normal controls (n=9) received an equivalent volume of citrate buffer. Weaned animals received free access to chow and water and a constant 12 hour on/12 hour off light cycle. Tail vein blood glucose was assessed weekly following an eight-hour fast, using Accu Chek Advantage glucometer. Animals received tap water (Normal and Diabetic Control) or 0.8 % NLE (Diabetic Treated) for six weeks. The results were expressed as means ± standard error of the mean using the Origin Pro 7.0 software. The significance of the mean difference between groups was determined with the IBM SPSS for Windows software version 23 via the paired samples T-test. Statistical significance of p<0.05 was used. The mortality was 74% pre-STZ (32.6% post-STZ) with 40.9% or 81.8% success (of STZinjected and STZ-survivors), respectively. Fasting blood glucose was significantly (p<0.05) elevated in the diabetic groups and was not alleviated by low-dose NLE. Because of the variability in mortality and success rates, further investigation is warranted for better reproducibility of the nSTZ T2DM model with minimal mortality. Furthermore, low-dose therapeutic NLE does not positively impact hyperglycemia and should not replace clinically prescribed medicines.