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OBJECTIVE Cannabinoids modulate do-pamine(DA)transmission and DA-related behavior,which has been thought to be mediated initially by acti-vation of cannabinoid CB1 receptors(CB1Rs)on GABA neurons.However,the cellular and receptor mechanisms underlying cannabinoids' psychoactive effects are not fully understood.The present study is to explore the pos-sible expression character of CB1Rs and elucidated the underlying mechanism of them.METHODS We took advantage of RNAscope in situ hybridization(ISH)assays and triple-staining assays to detect the CB1R-expressing neurons.We established an optical intracranial self-stimulation(OICSS)behavioral model by using opto-genetics to study dopaminergic reinforcement function.Natural and synthetic cannabinoids were used to study the function of CB1Rs.Conditional genetic depletion of CB1Rs and behavioral assay were performed to study the modulatory role of CB1Rs in DA-related behaviors.RESULTS We found that CB1Rs are also expressed in a subset of DA neurons and functionally underlie cannabi-noid action in male and female mice.ISH assays demon-strated CB1 mRNA in tyrosine hydroxylase(TH)-posi-tive DA neurons in the ventral tegmental area(VTA)and glutamate decarboxylase 1(GAD1)-positive GABA neu-rons.The CB1R expressing DA neurons were located mainly in the middle portion of the VTA with the number of CB1-TH colocalization progressively decreasing from the medial to the lateral VTA.Triple-staining assays indi-cated CB1R mRNA colocalization with both TH and vesicular glutamate transporter 2(VgluT2,a glutamate neuronal marker)in the medial VTA close to the midline of the brain.Optogenetic activation of this population of DA neurons was rewarding as assessed by OICSS.D9-tetrahydrocannabinol(D9-THC)or ACEA(a selective CB1R agonist)dose-dependently inhibited optical intra-cranial self-stimulation in DAT-Cre control mice,but not in conditional knockout mice with the CB1R gene absent in DA neurons.In addition,deletion of CB1Rs from DA neurons attenuated D9-THC-induced reduction in DA release in the NAc,locomotion,and anxiety.CONCLU-SION Our results indicated that CB1Rs are expressed in a subset of DA neurons that corelease DA and gluta-mate,and functionally underlie cannabinoid modulation of DA release and DA-related behavior.
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OBJECTIVE@#To observe the effect of moxibustion on oxidative stress injury of nigrostriatal system in rats with Parkinson's disease (PD) based on nuclear factor erythroid 2-related factor (Nrf2)/antioxidant response element (ARE) pathway, and to explore its mechanism.@*METHODS@#A total of 48 SD rats were randomized into a blank group, a sham-operation group, a model group and a moxibustion group, 12 rats in each group. Unilateral two-point injection with 6-hydroxydopamine (6-OHDA) was adopted in the model group and the moxibustion group to establish the PD model; the operation manipulation in the sham-operation group was the same as the model group and the moxibustion group, and the same volume of 0.9% sodium chloride solutions was given by unilateral two-point injection. Moxibustion was adopted at "Baihui" (GV 20) and "Sishencong" (EX-HN 1) in the moxibustion group for 20 min, once a day, 6 times a week for 6 weeks. No intervention was given in the other 3 groups. Morphology of right mesencephalon substantia nigra was observed by HE staining, the expression of tyrosine hydroxylase (TH) in right mesencephalon substantia nigra was detected by immunohistochemistry method, the expression of reactive oxygen species (ROS), malondialdehyde (MDA), glutathione (GSH), and glutathione peroxidase (GSH-Px) in corpus striatum was detected by colorimetry method, and the expression of Nrf2 and heme oxygenase-1 (HO-1) proteins was detected by Western blot in the 4 groups.@*RESULTS@#Clear tissue structure and complete dopaminergic neurons of right mesencephalon substantia nigra were observed in the blank group and the sham-operation group; unclear tissue structure, decreased and swelling dopaminergic neurons were observed in the model group; compared with the model group, more neurons were observed and the swelling of cyton was reduced in the moxibustion group. Compared with the sham-operation group, the expression of TH in right mesencephalon substantia nigra was decreased in the model group (<0.01); compared with the model group, the expression of TH in right mesencephalon substantia nigra was increased in the moxibustion group (<0.05). Compared with the sham-operation group, the expression of ROS, MDA was increased (<0.01), the expression of GSH, GSH-Px, Nrf2 and HO-1 was decreased in the model group (<0.01, <0.05); compared with the model group, the expression of ROS, MDA was decreased (<0.05, <0.01), the expression of GSH, GSH-Px, Nrf2 and HO-1 was increased in the moxibustion group (<0.05, <0.01).@*CONCLUSION@#Moxibustion can alleviate oxidative stress injury of nigrostriatal system in rats with Parkinson's disease by activating the Nrf2/ARE pathway, and protect the dopamine neurons.
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Aim To discuss the neuroprotection of an-tioxidant α-phenyl-N-tert-butyl nitrone ( PBN) in Par-kinson's disease ( PD) model. Methods The neuro-protective effects of PBN was explored on 1-methyl-4-phenylpyridinium/1-methyl-4-phenyl-1,2,3,6-tetrahy-dropyridine ( MPP+/MPTP ) induced PD models through a chemical releasing of free radicals in neurons and in vivo. Results PBN significantly scavenged chemical derived free radicals, reduced MPP+induced SH-SY5Y injury and enhanced neurons' viability. In MPTP induced PD model, PBN significantly enhanced the number of tyrosine hydroxylase ( TH)-positive do-pamine ( DA) neurons in the substantia nigra, restored the expression of Nrf2 and HO-1, and raised striatal contents of DA and its metabolites. Conclusion PBN has a potent neuroprotective effect against MPP+/MPTP induced PD models.