Effects of Melissa Officinalis Extract on Streptozotocin-Induced Diabetes in Rat Models; a Stereological Study

Background and objectives: Melissa officinalis (MO) has shown antioxidant and anti-inflammatory properties and is traditionally believed to have anti-hyperglycemic effects. This study aims to evaluate the protective effects of MO on streptozotocin (STZ) induced pancreatic damage and thereupon diabetes in rats. Methods: STZ (60 mg/kg) was injected intraperitoneally to the rats in order to induce diabetes mellitus (DM). Forty-eight rats were divided into four groups: control 1 (C1), healthy rats, control 2 (C2), non-treated diabetics, treatment groups 1 and 2 (T1, T2), the diabetics treated with 150 and 300 mg/kg MOorally, respectively, for 14 days. After sacrificing the models, their pancreases were extracted and sent for stereological evaluations.  Volume density (Vv; %), absolute volume of the islets (mm3), numerical density of the beta cells (Nv; per mm3), and the total number of the beta cells (×106), were measured. P-value < 0.05 was considered as statistically significant. Result: The treatmentgroups showedsignificant improvements in volume density and total volume of the islets, as well as the numerical density and the total number of the beta cells (p <0.001). The treatmentgroups also had significantly lower blood sugar compared to the untreated  group (p=0.008).  Conclusion: According to our results, MO has protective effects on the pancreatic beta cells against toxic chemicals such as STZ. However, further studies are needed to examine the beneficial effects and possible adverse effects of MO in other animalmodels and also in humans.