OBJECTIVE To study the effects of Ro 64-6198,a selective nociceptin/orphanin FQ receptor(NOPR)agonist,on heroin self-administration and drug-seeking behavior in rats.METHODS Rats were trained to self-administer heroin intravenously at a dose of 0.05 mg·kg-1 under a fixed ratio 1(FR1)reinforcement schedule.Heroin motivation was assessed using a progressive ratio(PR)schedule.Firstly,a stable heroin self-administered rat model was established before the effects of Ro 64-6198 on heroin rewarding under the FR1 schedule were observed.After three days of self-administration recovery training,the effects of Ro 64-6198 on heroin reward motivation were observed under the PR3-4 schedule.Following extinction,the reinstatement of heroin seeking induced by either conditioned cues or heroin priming was evaluated in rats withdrawn from self-administration.The expressions of cAMP response element-binding protein(CREB)and brain-derived neurotrophic factor(BDNF)in the ventral tegmental area(VTA)were analyzed using Western blotting,while the expression of the NOPR in neurons in the VTA was examined through immunofluorescence staining.RESULTS Pretreatment with 3 mg·kg-1 Ro 64-6198 significantly reduced active responses and heroin infusions during FR1 testing,as well as decreased breakpoints,indicating reduced motivation under the PR schedule.At a dose of 1 mg·kg-1,Ro 64-6198 markedly attenuated the reinstatement of heroin-seeking behavior induced by conditioned cues or heroin priming.Furthermore,the administration of SB-612111,an NOPR antagonist,blocked the inhibitory effects of Ro 64-6198 on cue-induced heroin-seeking,although SB-612111 alone had no effect on heroin-seeking behavior.Ro 64-6198 treatment also suppressed the reduction of both phos-phorylated CREB(p-CREB)and BDNF levels in the VTA and the decreased expression of NOPR and p-CREB in dopaminergic neurons of the VTA.CONCLUSION These results demonstrate that Ro 64-6198 can mitigate heroin-seeking behavior through NOPR activation and CREB/BDNF pathway in the VTA.This study is expected to offer evidence for its potential as a clinical treatment for heroin addiction and relapse.

OBJECTIVE To study the effects of Ro 64-6198,a selective nociceptin/orphanin FQ receptor(NOPR)agonist,on heroin self-administration and drug-seeking behavior in rats.METHODS Rats were trained to self-administer heroin intravenously at a dose of 0.05 mg·kg-1 under a fixed ratio 1(FR1)reinforcement schedule.Heroin motivation was assessed using a progressive ratio(PR)schedule.Firstly,a stable heroin self-administered rat model was established before the effects of Ro 64-6198 on heroin rewarding under the FR1 schedule were observed.After three days of self-administration recovery training,the effects of Ro 64-6198 on heroin reward motivation were observed under the PR3-4 schedule.Following extinction,the reinstatement of heroin seeking induced by either conditioned cues or heroin priming was evaluated in rats withdrawn from self-administration.The expressions of cAMP response element-binding protein(CREB)and brain-derived neurotrophic factor(BDNF)in the ventral tegmental area(VTA)were analyzed using Western blotting,while the expression of the NOPR in neurons in the VTA was examined through immunofluorescence staining.RESULTS Pretreatment with 3 mg·kg-1 Ro 64-6198 significantly reduced active responses and heroin infusions during FR1 testing,as well as decreased breakpoints,indicating reduced motivation under the PR schedule.At a dose of 1 mg·kg-1,Ro 64-6198 markedly attenuated the reinstatement of heroin-seeking behavior induced by conditioned cues or heroin priming.Furthermore,the administration of SB-612111,an NOPR antagonist,blocked the inhibitory effects of Ro 64-6198 on cue-induced heroin-seeking,although SB-612111 alone had no effect on heroin-seeking behavior.Ro 64-6198 treatment also suppressed the reduction of both phos-phorylated CREB(p-CREB)and BDNF levels in the VTA and the decreased expression of NOPR and p-CREB in dopaminergic neurons of the VTA.CONCLUSION These results demonstrate that Ro 64-6198 can mitigate heroin-seeking behavior through NOPR activation and CREB/BDNF pathway in the VTA.This study is expected to offer evidence for its potential as a clinical treatment for heroin addiction and relapse.

OBJECTIVE To investigate the role of the complement C3/C3aR signaling pathway in the prefrontal cortex and colon neuroglia cell interactions during meth-amphetamine(METH)addiction,to observe the effects of TLR4 inhibitors as well as complement C3 elimination on METH reward and relapse behavior,and to explore the neuroinflammatory mechanisms of complement C3 acti-vation in METH addiction.METHODS ①A 14 d and 28 d rat METH addiction model was established to observe the effects of TLR4 antagonist ibudilast 3 mg·kg-1 and 10 mg·kg-1 on self-administration,reward motivation,relapse,and natural reward behavior in METH-trained 14 d rats and the effects of 0.02 mg·kg-1 complement C3 antago-nist on self-administration behavior in METH-trained 28 d rats.② Differences in the expression of TLR4,NF-κB,GRP94,C3,cathepsin L,CD68,and GFAP in the pre-frontal cortex of each group were examined using West-ern blotting.③ In addition,the expression of ATF6 in the prefrontal cortex of each group and the effects on neuro-nal and microglia/macrophage INOS,CD206 GRP94,and complement C3/C3aR.RESULTS ① Endoplasmic reticulum stress occurred in neurons and microglia after METH exposure depending on GRP94 and unfolded pro-tein responses to the ATF6 pathway.In addition,it acti-vates the TLR4-NF-κB pathway.② Microglia with high complement C3/C3aR expression in the prefrontal cortex were recruited to synaptic pruning and phagocytic responses around neurons with high GRP94,comple-ment C3/C3aR expression and these effects were blocked by complement C3 antagonists.③ In the rec-tum,GRP94 functions as a molecular chaperone for com-plement C3 and cathepsin L.Crosstalk occurs between enteric neurons high in GRP94,complement C3,and macrophages high in C3aR,located in the submucosa,lamina propria,and muscular,respectively,and all of these effects are blocked by complement C3 antago-nists.④ Treatment with the TLR4 antagonist ibudilast inhibits self-administration,reward motivation,and cue-or METH-priming in METH-trained 14 d rats,but fails to affect natural reward behavior.Ibudilast treatment attenu-ates the TLR4-NF-κB inflammatory pathway and comple-ments C3/C3aR pathway in the prefrontal cortex.CON-CLUSION Activation of the complement C3/C3aR signal-ing pathway by TLR4-NF-κB inflammatory signaling in the prefrontal cortex mediates the METH addiction pro-cess,providing an experimental basis for the clinical treatment of METH addiction,and targeting TLR4/NF-κB inflammatory signaling and complement C3/C3aR may be a new way to intervene in METH addiction.

OBJECTIVE To investigate the effect of injection of β2-adrenergic receptor agonist clenbuterol into the infralimbic cortex(IL) on drug-seeking behavior triggered by conditioned cues. METHODS Adult male SD rats were trained to self-administer heroin under a FR1 schedule for consecutive 14 d,followed by 2-h extinction training. Cue-induced heroin seeking was measured for 2 h. Clenbuterol was microinjected bilaterally into the IL(8 ng/side)of rats 15 min prior to reinstatement test. Meanwhile,locomotor activity was detected 15 min after clenbuterol or artifial cerebrospinal fluid(mod?el group) was microinjected bilaterally into IL. Western blotting was used to detect the expression of phosphorylated cyclic AMP response element-binding protein(p-CREB)in the prelimbic cortex(PL), IL,nucleus accumbens core (NACc) and shell (NACsh) of rats immediately after reinstatement test. RESULTS After heroin administration training for 14 consecutive days,these animals exhibited reliable heroin self-administration,indicated by the increase in active nose poke responses and infusions. The rats that had received infusion of clenbuterol into the IL had significantly lower active pokes (8 ± 3)than those in model group(45±10)in cue-induced reinstatement(P<0.01),but there was no significant differ?ence between clenbuterol group and vehicle group in the locomotor activity. The expression of p-CREB in either IL or NACsh was significantly decreased in clenbuterol group compared with model group(P<0.01,P<0.05),but significantly increased in NACc(P<0.01). CONCLUSION Microinjection of clenb?uterol into the IL can attenuate the cue-induced reinstatement of heroin-seeking behavior in rats. The underlying mechanism might be related to the regulation of p-CREB expression in the NACc and NACsh.

Objective To assess whether propofol call induce stable psychic dependence in the rats by self-administration experiment. Methods Twenty-four male SD rats 14 weeks old weighing 240一270 mg were studied. Anesthesia was performed with intraperitoneal injection of 3%sodium pentoharbitsl 40 ms/kg and atropine 03 mg/kg.A catheter wag inserted into the right external jugular vein. Penicillin(100 000 U)0.2 ml wag injected through the external jugular vein for anti-infection and heparin sodium(50U/ml)0.1 ml for anticoagulation. The self-administration experiment of 14 days was started after the 7 days of recovery. All the rats were randomly divided into 4 groups(n=6 each):contontrol group(C),propofol 0.56 mg/kg/l group(P1),propofol 1.00 mg/kg group(P2)and pmpofol 1.70 ms/kg group(P3).The experimental events were controlled by a computer with 50 times of the maximum injection per day.The times ofactive and inactive nose-poke response and times of drug iniection were recorded per day.Results Compared with group C and P1,the times of active nosepoke response and injections were significantly increased in group P2 and P3(P<0.01).The times of active nosepoke response and injections per day were significantly increased in group P3 than in group P2(P(0.01).There was no significant difference in the times of active nose-poke response and injections between group C and P1.There was no significant difference in inactive nose-poke resporme between the 4 groups.And the total daily doses of propofol injected in the last 3 days were significantly increased in a dose-dependent manner.Conclusion Propefol can induce the development of psychological dependence in rata and it is related to the dosage.