Neuroprotective effects of pregabalin in a rat model of intracisternal facial nerve avulsion

BACKGROUND: Pregabalin (PGB), a drug used for treating neuropathic pain, has immune-modulating property that may have therapeutic implications. Suppression of microglial activation and improvement in functional recovery was observed in experimental spinal cord injury after PGB administration. An experimental study was conducted to evaluate whether PGB could afford neuroprotection in a rat model of intracisternal facial nerve avulsion. METHODS: Twenty-eight male Wistar rats (250-300 g) were dichotomized into two groups: a PGB group (N.=14) and a control group (N.=14). The PGB group received a total of 4 intraperitoneal PGB injections (30 mg/kg, 15 minutes preoperatively and 4, 24, and 48 hours postoperatively), and the control group underwent intraperitoneal saline injection. Intracisternal facial nerve avulsion was created by tangential pull-out of the nerve surgically exposed at the stylomastoid foramen. In both groups, the brainstem containing the facial motor nuclei neurons was thin-sliced and stained with cresyl violet, and the number of viable neurons in the facial motor nuclei on days 14 and 28 was counted under microscope. RESULTS: The total viable neuron count was significantly greater in the PGB group than in the Control group both on day 14 (271.4±14.9 vs. 196.2±22.2, P<0.01) and day 28 (160.2±21.6 vs. 102.6±13.4, P<0.01). Furthermore, CD11b/c immunostaining on days 3 and 8 showed that CD11b/c-positive cells, suggestive of activated microglia, were observed only in the control group. CONCLUSIONS: Better neuronal survival by PGB administration may be beneficial and clinically relevant when surgical reconstruction of the facial nerve, such as hypoglossal-facial nerve anastomosis, is considered.