The Expression And Distribution Of Metabotropic Glutamate Receptor 5 In The Prefrontal Cortex Under Neuropathic Pain

ObjectiveTo observe the relation between metabotropic glutamate receptor 5(m Glu R5) and emotion evoked by neuropathic pain in the medial prefrontal cortex(m PFC).Materials and MethodsMale Sprague Dawley rats were randomly divided into five groups, normal control group and 1, 3, 5, 7 d groups after L5 spinal nerve ligation(SNL). Immunofluorescence staining, Western Blotting and animal behavioral methods were employed to detect the expression level of m Glu R5 in the m PFC and pain-induced emotional response of rats in control and SNL groups.Results50% of mechanical paw withdrawal threshold(PWT) of rats after SNL decreased significantly. Open field test showed that rats after SNL had anxiety-like symptoms suggesting the success of neuropathic pain model. Inmmunofluorescence staining showed that m Glu R5 was mainly expressed in neurons, and the subtypes of GABAergic neurons including PV-, CR- and CB-positive neurons all expressed m Glu R5.Furthermore, the distribution pattern of m Glu R5 in the neuron changed and m Glu R5 was collected to neurites after SNL. Compared to control group, the expression level of m Glu R5 was significantly decreased(P<0.05) at the 7th day after SNL detected by Western Blot.ConclusionNeuropathic pain together with anxiety-like symptoms can cause decreased expression and change of distribution pattern of m Glu R5 in m PFC of rats. The present results suggested that m Glu R5 in the m PFC might be involved in neuropathic pain-induced anxiety-like behavior.