Chondroitin sulfate produces antinociception and neuroprotection in chronic constriction injury-induced neuropathic pain in rats by increasing anti-inflammatory molecules and reducing oxidative stress

Abstract

Objectives: Damage to the peripheral and central nervous system lead to Neuropathic pain (NP) which is a widespread and devitalizing condition. chondroitin sulfate (CS), has been used in managing joint pain and osteoarthritis. In this study, the effectiveness of CS on NP induced by chronic constriction injury (CCI) is examined.

Methods: Thirty Wistar rats were distributed at random into six groups (n = 5). Sciatic nerve ligation was carried out by encircling the nerve with four loose ligatures to induce NP. Allodynia (cold and mechanical) and heat hyperalgesia were assessed using Acetone, von Frey filament and Hot plate tests. CCI induction resulted to NP, prominent from the 3^rd day after surgery. Structural architecture of sciatic nerves was evaluated via histological examination of the transverse section of the nerves.

Results: Oral administration of CS (600 mg/kg and 900 mg/kg for 21 days) resulted in significant (P < 0.05) inhibition of allodynia (cold and mechanical) and thermal hyperalgesia. Lipid peroxidation, tumor necrosis factor-α (TNF-α), calcitonin gene related peptide (CGRP), C reactive protein (CRP), and oxidative stress were attenuated by CS. CS also improved interleukin (IL)-6, nitric oxide (NO), total antioxidant capacity (TAC).

Conclusion: These findings suggest that CS attenuates allodynia, and thermal hyperalgesia induced by CCI by downregulating TNF-α, CRP, CGRP, oxidative enzymes, and upregulating IL-6, NO, and TAC. Nociceptive behavioral studies and histological findings showed significant improvement in the CS treated groups compared to CCI rats. These findings are responsible for the beneficial effect of CS in NP.

Keywords: Chondroitin sulfate; chronic constriction injury; imipramine; neuropathic pain; sciatic nerve.

Figure 1

Chronic constriction injury Induction (a) exposed right sciatic nerve (b) ligated right sciatic nerve (c) sutured skin of the right hind limb

Figure 2

Chondroitin sulphate reversed thermal hyperalgesia in sciatic nerve-induced neuropathic pain. (a) Pre-surgery thermal test (b) 3^rd day thermal test (c) 10^th day thermal test (d) 17^th day thermal test (e) 24^th day thermal test. Data are expressed as the mean ± SEM (n = 5) assessed by two-way ANOVA followed by Tukey’s post hoc test. *#†P < 0.05, is significant versus. *=NC., #=SC., †=LC

Figure 3

Chondroitin sulphate reversed serum potassium and calcium (a) potassium concentration and (b) calcium concentration in rats. Data are expressed as the mean ± SEM (n = 5) subjected to one-way ANOVA followed by Tukey’s post hoc test. *#†P < 0.05 is significant versus *NC., #=SC., †=LC

Figure 4

Chondroitin sulphate reversed lipid peroxidation and antioxidant enzymes in rats. (a) sciatic nerve MDA concentraton (b) serum TAC concentration (c) sciatic nerve CAT concentration (d) sciatic nerve SOD concentration. Data are expressed as the mean ± SEM (n = 5) subjected to one-way ANOVA fllowed by Tukey’s post hoc test. *#†P < 0.05 is significant versus *NC., #=SC., †=LC. CAT: Catalase; SOD: Superoxide dismutase; TAC: Total antioxidant capacity

Figure 5

Chondroitin sulphate reversed serum C-reactive protein and calcitonin gene realated peptide (a) C reactive protein (b) calcitonin gene related peptide concentration in rats. Data are expressed as the mean ± SEM (n = 5) subjected to one-way ANOVA followed by Tukey’s post hoc analysis. *#†P < 0.05 is significant versus *NC., #=SC., †=LC

Figure 6

Chondroitin sulphate reversed brain nitric oxide and lactate dehydrogenase (LDH) (a) nitric oxide concentration and (b) LDH concentration in rats. Data are expressed as the mean ± SEM (n = 5) subjected to one-way ANOVA followed by Tukey’s post hoc test. *#†P < 0.05 is significant versus *NC., #=SC., †=LC

Figure 7

Chondroitin sulphate reversed serum inflammatory cytokines (a) interleukin -6 (b) Tumor necrosis factor-α (c) NF-κB concentration in rats. Data are expressed as the mean ± SEM (n = 5) subjected to one-way ANOVA followed by Tukey’s post hoc test. *#†P < 0.05 is significant versus *NC., #=CS., †=LC. NC: Non-ligated control: SC: Sham control; LC: Ligated control; CS1: Chondroitin sulphate 600 mg/kg; CS2: Chondroitin sulphate 900 mg/kg; IMI: imipramine 10 mg/kg

Figure 8

Histological analysis of rat sciatic nerves on day 22 after surgery. (a and b) sciatic nerve of non-ligated rat showed that the myelin sheets were well organized round axons and there were absence of infiltrating cells; (c) Sciatic nerve of ligated untreated rat shows several areas of edema (black sphere), presence of infiltrating cells (polymorphs and lymphocytic) (+) (significant inflammation), vacuolization (*), degraded myelin sheets (myelin ellipsoids) (i); (d) ligated sciatic nerve treated with C.S. 600 mg/kg (e) ligated sciatic nerve trated with C.S. 900 mg/kg (h) ligated sciatic nerve treated with imipramine 10 mg/kg. d-f show properly alleviated edema, improved myelin sheets organization, well reduced vacuolization, fewer infiltrating cells compared to the ligated untreated. H and E staining was used