Cannabinoid receptor 1 regulates the spatial learning and memory function and the expression of NR1 subunit of N-methyl-D-aspartic acid receptor in medial prefrontal cortex of neuropathic pain model rat / 中华神经科杂志

ABSTRACT

Objective To investigate the effect of cannabinoid receptor 1 ( CBR1 ) on spatial learning and memory function of neuropathic pain ( NP ) model rats and the expression of N-methyl-D-aspartic acid receptor 1(NR1) subunit in medial prefrontal cortex (mPFC).Methods Thirty-six healthy male Wistar rats were randomly divided into 4 groups, with 9 rats in each group the sham operated group (SO group), the neuropathic pain model group (NP group), the NP model group with an mPFC injection of saline ( NS group ) , and the NP model group with an mPFC injection of the CBR 1 antagonist AM251 ( AM251 group).The NP model was prepared using the operation of chronic constriction injury ( CCI) of the right sciatic nerve.The mechanical withdrawal threshold ( MWT ) and the thermal withdrawal latency (TWL) of the rats in each group were detected at 3, 7, 14, 21 and 28 days after the operation.At 29 days after the operation , 18 rats of NP model were randomly selected and given an mPFC injection of saline or AM251 using a three-dimensional brain puncture.At days 30-37 after operation , the eight-arm maze test was performed to detect the spatial learning and memory function of the rats , and the rats were sacrificed immediately after this test.The expression levels of CBR1, NR1 and phosphorylated-N-methyl-D-aspartic acid receptor 1 ( p-NR1 ) ( Ser896 ) in the mPFC brain region were detected by Western blotting , RT-PCR and immunofluorescence.Results Compared with the SO group , the pain thresholds and the spatial learning and memory function of the rats in the NP group were significantly lower ( both P <0.05 ).Compared with the NS group , the rats in the AM251 group showed improvement about spatial learning and memory function ( P<0.05).Compared with the SO group ( the mRNA and protein level of CBR 10.23 ± 0.06,0.42 ±0.03), the mRNA(0.43 ±0.12) and protein (0.53 ±0.05) level of CBR1 in NP group increased (both P<0.05).Compared with the NS group (the mRNA and protein level of CBR10.42 ± 0.11,0.52 ±0.10), the mRNA (0.53 ±0.05) and protein (0.98 ±0.17) level of CBR1 in AM251 group increased (both P<0.05).Compared with the SO group (the mRNA and protein level of NR1 and the protein level of p-NR11.50 ±0.15,0.65 ±0.05,0.79 ±0.15), the mRNA (0.94 ±0.07) and protein (0.24 ±0.05) level of NR1 in NP group decreased (both P<0.05), the protein level of p-NR1 (0.33 ± 0.04) decreased (P<0.05).Compared with the NS group (the mRNA and protein level of NR1 and the protein level of p-NR11.09 ±0.14,0.26 ±0.06,0.31 ±0.08), the mRNA(1.58 ±0.10) and protein (1.42 ±0.10) level of NR1 in AM251 group increased (both P<0.05), the protein (0.95 ±0.15) level of p-NR1 increased ( P<0.05).Conclusion CBR1 can decrease the expression level of NR 1 and p-NR1 in the mPFC brain region of NP model rats and induce the spatial learning and memory impairment.