Crocin enhanced functional recovery after sciatic nerve crush injury in rats

Abstract

Objective(s): Crocin is a constituent of saffron and has many biological functions. The present study aimed to investigate the effects of intraperitoneal (IP) injection of crocin on sciatic nerve regeneration in male Wistar rats.

Materials and methods: Fifty-four rats were divided into 9 groups: groups 1-4 (intact + normal saline and intact + crocin at doses of 5, 20 and 80 mg/kg, respectively); group 5 (sham surgery + normal saline); groups 6-9 (crush + normal saline and crush + crocin at doses of 5, 20 and 80 mg/kg, respectively). Normal saline and crocin were IP injected for 10 consecutive days after induction of a standard crush injury in left sciatic nerve. Footprints were obtained 1 day before and weekly after induction of nerve injury for evaluation of sciatic functional index (SFI). Blood samples were taken for evaluation of malondialdehyde (MDA) levels. Histopathological changes of sciatic nerve were investigated by light microscopy.

Results: Sciatic nerve crush-injured rats showed SFI values reduction, increased plasma MDA levels and produced Wallerian degeneration in sciatic nerve. Crocin at a dose of 5 mg/kg had no significant effects. At doses of 20 and 80 mg/kg, crocin accelerated the SFI recovery, decreased MDA levels and reduced Wallerian degeneration severity.

Conclusion: The present study suggests that the neuroprotective effects afforded by crocin may be due in part to reduction of free radicals-induced toxic effects.

Keywords: Crocin; Crush injury; Functional recovery; Rats; Sciatic nerve.

Figure 1

Effect of intraperitoneal (IP) injections of normal saline and crocin on sciatic functional index in sciatic nerve-crushed rats. Data are presented as mean ± SEM (n = 6). *P< 0.05 denotes significant difference vs day one before crush. ^†P< 0.05 denotes significant difference vs crush + normal saline group

Figure 2

Effect of IP injections of crocin on plasma malondialdehyde (MDA) levels in sciatic nerve-crushed at days 15 (A) and 30 (B) after crush in rats. Data are presented as mean ± SEM (n = 6). *P< 0.05 denotes significant difference vs other groups

Figure 3

Effect of IP injections of crocin on histopathological changes in distal segment of sciatic nerve induced by crush injury in rats. Data are presented as mean ± SEM (n = 6). *P< 0.05 denotes significant difference vs. crush + normal saline group

Figure 4

Histological analysis of rat sciatic nerve (A): Intact animals were not submitted to nerve crush and received normal saline (IP). it was observed normal architecture of sciatic nerve. (B and C): Animals submitted to sciatic nerve crush injury and treated with IP injections of normal saline and crocin (5 mg/kg), respectively. It was observed several areas of edema (*), vacuolization (+) and degraded myelin sheath (myelin ellipsoid) (>). (D and E): Sciatic nerve crushed animals received crocin at doses of 20 and 80 mg/kg, respectively. Few areas of edema, vacuolization and degraded myelin (myelin ellipsoid) were observed. (H&E × 400)