Effects of L-arginine on the expression of nitric oxide synthase in facial nerve in traumatic facial paralysis rats / 实用口腔医学杂志

ABSTRACT

Objective:To study the effects of NO precursor, L-arginine(L-Arg) and constitutive nitric oxide synthase(cNOS) inhibitor, L-nitroarginine(L-NNA)) on the expression of cNOS in facial nerve and surrounding tissues in traumatic facial paralysis rats. Methods:Facial paralysis was surgicaly created by impact in 57 SD rats. The rats were divided into 3 groups with 18 in each group, another 3 rats were used for morphological study. L-Arg at 40 mg/kg or L-NNA at 50 mg/kg were intraperitoneally injected into rats 2 times a day, from 4 days before untill 14 days after surgery(group L-Arg and group L-NNA). In control group(NS) same volume of normal saline was given to the rats after creation of facial paralysis. The facial nerve and surrounding tissue samples were obtained at different time. Immunohistochemical ABC method was used to examine cNOS and inducible NOS (iNOS) expression in facial nerve and surrounding tissues. Results:cNOS immunoreactivity was observed in traumatic facial nerve in L-Arg group 7 days after trauma and in the adjacent muscle in the 3 groups from 6 h to 3 d after trauma. iNOS was found in the paralyzed nerves from 1 d to 7 d after trauma in the 3 groups, and in the adjacent tissues from 6 h to 3 d after trauma in the 3 groups. Conclusions:L-Arg may stimulate constitutive NOS expression in facial nerve and probably promote the nerve regeneration.