Hepatic and renal effects of oral stingless bee honey in a streptozotocin-induced diabetic rat model

Abstract

Background: Diabetes is known damage the liver and kidney, leading to hepatic dysfunction and kidney failure. Honey is believed to help in lowering the blood glucose levels of diabetic patients and reducing diabetic complications. However, the effect of stingless bee honey (SBH) administration in relieving liver and kidney damage in diabetes has not been well-studied.

Aim: To investigate the effect of SBH administration on the kidney and liver of streptozotocin-induced (STZ; 55 mg/kg) diabetic Sprague Dawley rats.

Methods: The rats were grouped as follows (n = 6 per group): non-diabetic (ND), untreated diabetic (UNT), metformin-treated (MET), and SBH+metformin-treated (SBME) groups. After successful diabetic induction, ND and UNT rats were given normal saline, whereas the treatment groups received SBH (2.0 g/kg and/or metformin (250 mg/kg) for 12 d. Serum biochemical parameters and histological changes using hematoxylin and eosin (H&E) and periodic acid-Schiff (PAS) staining were evaluated.

Results: On H&E and PAS staining, the ND group showed normal architecture and cellularity of Bowman's capsule and tubules, whereas the UNT and MET groups had an increased glomerular cellularity and thickened basement membrane. The SBH-treated group showed a decrease in hydropic changes and mild cellularity of the glomerulus vs the ND group based on H&E staining, but the two were similar on PAS staining. Likewise, the SBME-treated group had an increase in cellularity of the glomerulus on H&E staining, but it was comparable to the SBH and ND groups on PAS staining. UNT diabetic rats had tubular hydropic tubules, which were smaller than other groups. Reduced fatty vacuole formation and dilated blood sinusoids in liver tissue were seen in the SBH group. Conversely, the UNT group had high glucose levels, which subsequently increased MDA levels, ultimately leading to liver damage. SBH treatment reduced this damage, as evidenced by having the lowest fasting glucose, serum alanine transaminase, aspartate transaminase, and alkaline phosphatase levels compared to other groups, although the levels of liver enzymes were not statistically significant.

Conclusion: The cellularity of the Bowman's capsule, as well as histological alteration of kidney tubules, glomerular membranes, and liver tissues in diabetic rats after oral SBH resembled those of ND rats. Therefore, SBH exhibited a protective hepatorenal effect in a diabetic rat model.

Keywords: Diabetes; Hematoxylin and eosin; Kidney; Liver; Periodic acid–Schiff; Stingless bee honey; Streptozotocin.

Figure 1

MDA level in diabetic rats in response to different treatments over 12 d. Data were analyzed using one-way analysis of variance, followed by Tukey’s post-test. Data showed in mean ± SEM; ^a,bP < 0.05. ND: Non-diabetic group; UNT: Untreated diabetic group; SBH: Stingless bee honey group; MET: Metformin group; SBME: Stingless bee honey plus metformin group.

Figure 2

H&E staining of kidney tissue samples on day 13. A: Tissue sample for the non-diabetic control group; B: Untreated (UNT) diabetic group; C: Stingless bee honey (SBH) treatment group; D: Metformin (MET) treatment group; E: Stingless bee honey plus metformin (SBME) treatment group. The UNT group showed an increase in glomerular cellularity and tubular hydropic changes. The MET and SBME groups showed high cellularity and mesangial matrix expansion. The SBH group showed a decrease in hydropic changes and mild cellularity of the glomerulus (H&E staining, 40 ×). G: Glomerulus; CB: Capsule Bowman; T: Tubules; HC: Hydropic changes; IC: Increased cellularity; C: Capillary; M: Mesangial cell; MC: Mild cellularity.

Figure 3

Periodic acid–Schiff staining of kidney tissue sample on day 13. A: Tissue sample for the non-diabetic (ND) control group; B: Untreated (UNT) diabetic group; C: Stingless bee honey plus metformin (SBME) treatment group; D: Stingless bee honey (SBH) treatment group; E: Metformin (MET) treatment group. The ND control group showed normal kidney tissue architecture. The UNT group had hydropic tubules and thickened basement membrane of the glomeruli, tubules, and blood capillaries. The SBH group showed improvement in these basement membrane changes. The MET group showed mild thickening of the glomerular basement membrane. The SBME group showed improvement of the basement membrane (PAS staining, 40 ×). G: Glomerulus; TBM: Thin layer basement membrane of glomeruli; T: Tubules; THBM: Thickening basement membrane of glomeruli; TT: Thickening basement membrane of tubules; AT: Atrophic tubules; MTBM: Mild thickening basement membrane of glomeruli.

Figure 4

H&E staining of liver tissue sample on day 13. A: Tissue sample for the non-diabetic (ND) control group; B: Untreated (UNT) diabetic group; C: Stingless bee honey (SBH) treatment group; D: Metformin (MET) treatment group; E: Stingless bee honey plus metformin (SBME) treatment group. The ND control group showed normal liver architecture. The UNT group had lipid droplet formation in hepatocytes with dilated blood sinusoids and congestion surrounding central veins. The SBH group showed significant reduction in steatosis and sinusoid congestion. The MET group showed a reduction in steatosis, but sinusoids congestion was still present. The SBME group had decreased lipid droplet formation and dilated blood sinusoids (H&E staining, 40 ×). CV: Central vein; BS: Blood sinusoids; H: Hepatocytes; LD: Lipid droplet; DBS: Dilated blood sinusoids.

Figure 5

Periodic acid–Schiff staining of liver tissue sample on the 13^th day of study. A: Tissue sample for the non-diabetic (ND) control group; B: Untreated diabetic (UNT) group; C: Stingless bee honey (SBH) treatment group; D: Stingless bee honey plus metformin (SBME) treatment group; E: Metformin treatment (MET) group. The ND control group showed normal architecture. The UNT group showed an increase in glycogen content. The SBH diabetic group showed a reduction in glycogen content. The MET group showed an increase in glycogen content. The SBME group showed a reduction in glycogen content (PAS staining, 40 ×). CV: Central vein; GC: Glycogen content showed an increase in glycogen content.