*3.3. PRHE Ameliorates Diabetes-Induced Renal Functional and Structural Impairments*

Diabetic rats exhibited a significant increase in kidney weight/body weight ratio, serum creatinine, and microalbuminuria and a reduction in creatinine clearance (Table 2). These changes were significantly reduced, to a similar extent, when treated with PRHE, metformin, or both. In agreement with renal functions, kidney sections obtained from diabetic rats displayed perihilar focal segmental mesangial cell proliferation with mesangial area expansion and collagen deposits, together with a larger glomerular volume than normal rats (Figure 3, first panel). Immunofluorescence staining of CD34, a mesangial cell marker, also verified the presence of mesangial proliferation (Figure 3, second panel). Electron micrograph clearly showed glomerular basement membrane thickening with diffuse and extensive podocyte effacement (Figure 3, third panel), including the smaller size, abnormal shape, and decreased number of mitochondria within the proximal tubules (Figure 3, last panel). All these changes were significantly attenuated upon treatment with PRHE, metformin, or both.

**Table 2.** Effects of purple rice husk extract (PRHE) and metformin on renal function.


Values are the mean ± SD (*n* = 6). NDV: vehicle-treated normal group; DMV: vehicle-treated diabetic group; DMM: metformin-treated diabetic group; DME: PRHE-treated diabetic group; DMME: metformin plus PRHE-treated diabetic group; KW: kidney weight; BW: body weight. a,b Mean values with different letters in the same row are significantly different (*p* < 0.05).

**Figure 3.** Photomicrographs of the kidney tissues following purple rice husk extract (PRHE) and metformin treatment. First panel shows kidney sections stained with hematoxylin and eosin (H&E, 40×). The second panel shows immunofluorescence staining of CD34 (magnification, 40×). The third and last panels show transmission electron micrographs of glomerulus and renal tubules, respectively (original magnification: 3000×). The boxed areas are magnified in the right lower panel. NDV: vehicle-treated normal group; DMV: vehicle-treated diabetic group; DMM: metformin-treated diabetic group; DME: PRHE-treated diabetic group; DMME: metformin plus PRHE-treated diabetic group.
