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.
ABSTRACT
Objective To investigate the effect of lipid soluble fraction in the radix of Salvia miltiorrhiza (FSM) on conditioned place preference (CPP) in mice induced by morphine and preliminarily identify the fraction in the radix of S. miltiorrhiza. MethodsMorphine or NS was sc injected every other day to induce the obvious CPP in mice for 6 d. Before 30 min of sc injecting morphine, mice were ip administered different doses of lipid soluble fraction in the radix of S. miltiorrhiza. RP-HPLC method was used to identify the major component in the lipid soluble fraction in the radix of S. miltiorrhiza. ResultsThe staying time in morphine-paired white compartment was significantly prolonged. After treatment with lipid soluble fraction in the radix of S. miltiorrhiza (40 mg/kg, ip), the staying time in morphine-paired white compartment was significantly shortened (P