Neuropathic pain(NP)is caused by leision or disease of the somatic sensory nervous system,and its pathological mechanism is complex,mainly related to abnormal neural structure and function.It is hard for existing treatment methods to obtain satisfactory results.With the deepening of the study of peroxisome proliferate activation receptor-γ(PPAR-γ),its role in neuroinflammation,oxidative stress,ion channels,mitochondrial function,neuroprotection and other aspects have been discovered succes-sively,PPAR-γ may be one new target for pain prevention and treatment.This paper reviews the role of PPAR-γ in NP and related mechanisms,in order to provide new thinking for the clinical treatment of NP.

Objective To investigate the effects and possible mechanisms of melatonin on long-term cognitive impairments induced by repeated neonatal sevoflurane exposures.Methods Ninety-six neo-natal male SD rats at postnatal day 6,weighed 10-15 g,were randomly divided equally into four groups:the control group(group C),the melatonin group(group M),the sevoflurane group(group S),and the sevoflurane+melatonin group(group SM),24 rats in each group.Group C received free food and water.Group M received one intraperitoneal injection of melatonin 10 mg/kg per day for three consecutive days starting on postnatal day 6,and started drinking melatonin-containing water after cage separation on day 21.Group S inhaled 3%sevoflurane for 2 hours per day for three consecutive days starting on postnatal day 6.Group SM received one daily intraperitoneal injection of melatonin 10 mg/kg followed by inhalation of 3%sevoflurane for 2 hours per day for three consecutive days starting on postnatal day 6,and melatonin-contai-ning water was started on postnatal day 21 after cage separation.Open field test was performed on postnatal day 35,novel object recognition was performed on postnatal day 36,and the fear conditioning tests were performed from postnatal day 37 to 39.Rat brain tissues were taken on postnatal day 8 and day 40,the con-tent of iNOS and CD68 protein in the prefrontal cortex was detected by Western blot,and the concentration of IL-6 and IL-1β was detected by ELISA.Results Compared with group C,the discrimination index was significantly decreased,the freezing time was significantly shortened,the content of iNOS and CD68 protein,and the concentration of IL-6 and IL-1β in the prefrontal cortex were significantly increased on post-natal day 8 in group S(P＜0.05).Compared with group S,the discrimination index was significantly in-creased,the freezing time was significantly prolonged,the content of iNOS and CD68 protein,and the con-centration of IL-6 and IL-1β in the prefrontal cortex were significantly decreased on postnatal day 8 in group SM(P＜0.05).There were no statistically significant differences in the content of iNOS and CD68 protein,and the concentration of IL-6 and IL-1β in the prefrontal cortex between the four groups on postnatal day 40.Conclusion Melatonin can inhibit the inflammatory response in the prefrontal cortex and improve long-term cognitive impairments in neonatal rats induced by repeated neonatal sevoflurane exposures.