Effect of mPFC neuron synaptic plasticity changes in the formation of morphine related reward memory / 中华行为医学与脑科学杂志

ABSTRACT

Objective To observe the effect of mPFC neuron synaptic plasticity changes in the formation of morphine related reward memory.Methods 40 SD rats were administered morphine (10 mg/kg,ip) or saline (2 ml/kg,ip)and sacrificed 0,2,4 and 8 h after the treatment.The temporal profile of activity-regulated cytoskeleton-associated protein (Arc/Arg 3.1) expression in medial prefrontal cortex (mPFC) was analyzed.Another 40 rats receiving a single injection of morphine at different doses (0,5,10 or 20 mg/kg),and rats were sacrificed by decapitation 2 h later.In mPFC,changes of Arc/Arg 3.1 protein was analyzed by Western Blot,Arc/Arg 3.1 positive cells was detected by immunohistochemistry (IHC),and number of spines were analyzed by Golgi-cox method.In the second experiment,CPP model was established by 5 mg/kg morphine for 8 days.Arc/Arg 3.1 antisense oligodeoxynucleotide (AS) or the control (CS) was microinjected into mPFC 15 minutes before each morphine injection,then CPP score was evaluated.Results Compared with saline groups,Arc/Arg 3.1 protein,Arc/Arg 3.1 positive cells,number of spines ((1.01±0.04) vs (1.58±0.18),P＜0.01 ; (42.80±7.63) vs (74.47±8.02),P＜0.01 ;(17.27±5.64) vs (39.47±7.56),P＜0.01) were significantly increased 2 hours after morphine administration.All three doses of morphine (5,10 and 20 mg/kg) increased Arc/Arg 3.1 protein expression in the mPFC,and there were no dose-dependent effects.In CPP experiments,compared with microinjection of Arc/Arg 3.1 CS (0.74±0.02),Arc/Arg 3.1 AS microinjection significantly decreased the CPP score (0.51±0.01) in morphine group (P＜0.01).Conclusion It is enough to increase Arc/Arg 3.1 protein content and synaptic plasticity in mPFC by 10 mg/kg,and the changes implied in formation of morphine relative reward memory.