Promising Effects of Curcumin on Axon Morphology in a Streptozotocin-Induced Diabetic Female Rat Model: Responses to Early, Simultaneous, and Late Treatments

Abstract

A common complication of diabetes mellitus (DM), peripheral neuropathy, is frequently discussed. This research examined the role of curcumin-induced treatment models against the devastating effects of diabetes. Wistar albino female rats (n=56) were randomly divided into seven groups. The control group did not receive any special procedure. Five mL/kg of corn oil by intragastric gavage was given to the Sham group. Streptozotocin was administered intraperitoneally at 50 mg/kg in the DM group. Curcumin (30 mg/kg) was given to the treatment groups for 14 days. These were then divided into three further groups: the early treatment group (DC1) was applied curcumin seven days after DM induction, the late treatment group (DC2) after 21 days, and the simultaneous treatment group (DC3) received curcumin concurrently with induction. The curcumin group received only 30 mg/kg of curcumin for 14 days. 30 mg/kg of curcumin was given to the DM + curcumin group (DC1) via intragastric gavage once daily for 14 days, starting seven days after diabetes induction. The DM + curcumin group (DC2) received 30 mg/kg curcumin intragastric gavage once daily for 14 days, starting 21 days after the onset of diabetes. 30 mg/kg of curcumin was applied to the DM + curcumin (Cur) group (DC3) via intragastric gavage once daily for 14 days, simultaneously with the onset of diabetes. 30 mg/kg of curcumin was given to the Cur group via intragastric gavage once daily for 14 days. Stereological methods were used for morphoquantitative analysis of myelin thickness, myelinated axon areas, and axon numbers. The axon area decreased in the DM group compared with the control group. Large-diameter axons were shown in the DC1 group. Decreased axon areas and myelin sheath thicknesses were observed in the DC2 and DC3 groups. Curcumin encourages axonal regeneration in terms of axon area and myelin sheath thickness when administered in the early stage of diabetes induction but not when given simultaneously or late.