Neuropathic pain is caused by damage or malfunctioning of the nervous system. It is fairly common and more resistant to treatment than other types of
pain. Since
nitecapone, an inhibitor of
catechol-O-methyl-
transferase (COMT), has decreased neuropathic symptoms in diabetic rats, we studied its effects in another model of
neuropathic pain, the spinal nerve
ligation (SNL) model. Spinal nerves L5-6 were ligated in male Wistar rats under anaesthesia to produce the SNL model of
neuropathic pain.
Nitecapone (30 mg/kg, i.p.) or vehicle was administered once daily starting either 1h before or 2 days after surgery and continued for 14-19 days. Threshold for
mechanical allodynia was measured with the digital von Frey test and responses to cold stimuli with the
acetone test, before surgery and every other day after it 1h before
drug administration. Mechanical and cold
allodynia developed in all study groups. Both
nitecapone treatments significantly reduced
mechanical allodynia and withdrawal thresholds were 80-95% higher compared with the control group. In the
acetone test, both
nitecapone groups also showed less signs of cold
allodynia than the control groups. In
nitecapone-naïve animals a single dose of
nitecapone also reduced
mechanical allodynia on the 14th day after the surgery.
Nitecapone reduced the symptoms of
neuropathic pain after the SNL, which is in line with the earlier study. Our results suggest that
nitecapone and other COMT inhibitors should be studied further in the treatment of
neuropathic pain.