Efficacy of orally administered montmorillonite in myoglobinuric acute renal failure model in male rats

Abstract

Objectives: Acute kidney injury can be associated with serious consequences and therefore early treatment is critical to decreasing mortality and morbidity rate. We evaluated the effect of montmorillonite, the clay with strong cation exchange capacity, on the AKI model in rats.

Materials and methods: Glycerol (50% solution, 10 ml/kg) was injected in the rat hind limbs to induce AKI. 24 hr after induction of acute kidney injury, the rats received oral doses of montmorillonite (0.5 g/kg or 1 g/kg), or sodium polystyrene sulfonate (1 g/kg) for three consecutive days.

Results: Glycine induced acute kidney injury in rats with high levels of urea (336.60± 28.19 mg/dl), creatinine (4.10± 0.21 mg/dl), potassium (6.15 ± 0.28 mEq/L), and calcium (11.52 ± 0.19 mg/dl). Both doses of montmorillonite (0.5 and 1 g/kg) improved the serum urea (222.66± 10.02 and 170.20±8.06, P<0.05), creatinine (1.86±0.1, 2.05± 0.11, P<0.05), potassium (4.68 ± 0.4, 4.73 ± 0.34, P<0.001) and calcium (11.15 ± 0.17, 10.75 ± 0.25, P<0.01) levels. Treatment with montmorillonite especially at a high dose reduced the kidney pathological findings including, tubular necrosis, amorphous protein aggregation, and cell shedding into the distal and proximal tubule lumen. However, administration of SPS could not significantly decrease the severity of damages.

Conclusion: According to the results of this study, as well as the physicochemical properties of montmorillonite, such as high ion exchange capacity and low side effects, montmorillonite can be a low-cost and effective treatment option to reduce and improve the complications of acute kidney injury. However, the efficacy of this compound in human and clinical studies needs to be investigated.

Keywords: Acute renal failure; Bentonite; Clay; Kidney; Montmorillonite; Rhabdomyolysis.

Figure 1

Evaluation of serum urea level in a model of AKI. Animals received intramuscular injections of 50% glycerol on the first day of the experiment and DW, MMT (0.5 or 1 g/kg), or SPS (1 g/kg) for the next three days through oral administration. The other three groups only received DW (Control), MM (1 g/kg), or SPS. For statistical comparison, one-way ANOVA and Tukey–Kramer test were used. Data are expressed as mean±SE. *** P<0.001 compared with the control group, # P<0.05 compared with the glycerol group

Figure 2

Evaluation of serum creatinine level in a model of AKI. Different groups received glycerol plus DW, MMT (0.5 or 1 g/kg), MMT (1 g/kg), or SPS (1 g/kg). Animals received intramuscular injections of 50% glycerol on the first day of the experiment and DW, MMT, or SPS for the next three days through oral administration. The other three groups only received DW (Control), MM, or SPS. For statistical comparison, one-way ANOVA and Tukey–Kramer test were used. Data are expressed as mean ± SD. *** P<0.001 compared with the control group, # P<0.05 and ##P<0.01 compared with the glycerol group

Figure 3

Evaluation of serum CPK level in a model of AKI. Different groups received glycerol plus DW, MMT (0.5 or 1 g/kg), MMT (1 g/kg), or SPS (1 g/kg). Animals received intramuscular injections of 50% glycerol on the first day of the experiment and DW, MMT, or SPS for the next three days through oral administration. The other three groups only received DW (Control), MM, or SPS. For statistical comparison, one-way ANOVA and Tukey–Kramer test were used. Data are expressed as mean±SD. ** P<0.01 compared with the control group, # P<0.05 and ##P<0.01 compared with the glycerol group

Figure 4

Evaluation of body weight changes (A) and kidney hypertrophy index (B) in a model of AKI. Different groups received glycerol plus DW, MMT (0.5 or 1 g/kg), MMT (1 g/kg), or SPS (1 g/kg). Animals received intramuscular injections of 50% glycerol on the first day of the experiment and DW, MMT, or SPS for the next three days through oral administration. The other three groups only received DW (distilled water) (Control), MM, or SPS. For statistical comparison, one-way ANOVA and Tukey-Kramer test were used. Data are expressed as mean ± SD. ** P<0.01, ***P<0.001 compared with the control group, # P<0.05 compared with the glycerol group

Figure 5

A1) Photomicrographs of hematoxylin and eosin-stained sections of renal tissue of rat. Different groups received glycerol plus DW, MMT (0.5 or 1 g/kg), MMT (1 g/kg), or SPS (1 g/kg). Animals received intramuscular injections of 50% glycerol on the first day of the experiment and DW, MMT, or SPS for the next three days through oral administration. The other three groups only received DW (Control), MM, or SPS. A) Control group with normal tissue structure, B) High tubular necrosis and amorphous protein aggregation in the group-received glycerol, C) Tubular necrosis up to 20% in the group that received glycerol plus MMT 0.5 g/kg, D) Tubular necrosis up to 10% in the that received glycerol plus MMT 1 g/kg (magnification: 10 x 20x), and E) tubular necrosis up to 25% in the group that received glycerol plus SPS. A2) Histopathological damages in the kidney were evaluated and the score was between severe = +++, moderate = ++, mild = +, and normal histology