Activation of Cannabinoid Receptor 1 in GABAergic Neurons in the Rostral Anterior Insular Cortex Contributes to the Analgesia Following Common Peroneal Nerve Ligation / 神经科学通报·英文版

The rostral agranular insular cortex (RAIC) has been associated with pain modulation. Although the endogenous cannabinoid system (eCB) has been shown to regulate chronic pain, the roles of eCBs in the RAIC remain elusive under the neuropathic pain state. Neuropathic pain was induced in C57BL/6 mice by common peroneal nerve (CPN) ligation. The roles of the eCB were tested in the RAIC of ligated CPN C57BL/6J mice, glutamatergic, or GABAergic neuron cannabinoid receptor 1 (CB1R) knockdown mice with the whole-cell patch-clamp and pain behavioral methods. The E/I ratio (amplitude ratio between mEPSCs and mIPSCs) was significantly increased in layer V pyramidal neurons of the RAIC in CPN-ligated mice. Depolarization-induced suppression of inhibition but not depolarization-induced suppression of excitation in RAIC layer V pyramidal neurons were significantly increased in CPN-ligated mice. The analgesic effect of ACEA (a CB1R agonist) was alleviated along with bilateral dorsolateral funiculus lesions, with the administration of AM251 (a CB1R antagonist), and in CB1R knockdown mice in GABAergic neurons, but not glutamatergic neurons of the RAIC. Our results suggest that CB1R activation reinforces the function of the descending pain inhibitory pathway via reducing the inhibition of glutamatergic layer V neurons by GABAergic neurons in the RAIC to induce an analgesic effect in neuropathic pain.

Aucubin Promotes Differentiation of Neural Precursor Cells into GABAergic Neurons

Aucubin is a small compound naturally found in traditional medicinal herbs with primarily anti-inflammatory and protective effects. In the nervous system, aucubin is reported to be neuroprotective by enhancing neuronal survival and inhibiting apoptotic cell death in cultures and disease models. Our previous data, however, suggest that aucubin facilitates neurite elongation in cultured hippocampal neurons and axonal regrowth in regenerating sciatic nerves. Here, we investigated whether aucubin facilitates the differentiation of neural precursor cells (NPCs) into specific types of neurons. In NPCs cultured primarily from the rat embryonic hippocampus, aucubin significantly elevated the number of GAD65/67 immunoreactive cells and the expression of GAD65/67 proteins was upregulated dramatically by more than three-fold at relatively low concentrations of aucubin (0.01 µM to 10 µM). The expression of both NeuN and vGluT1 of NPCs, the markers for neurons and glutamatergic cells, respectively, and the number of vGluT1 immunoreactive cells also increased with higher concentrations of aucubin (1 µM and 10 µM), but the ratio of the increases was largely lower than GAD expression and GAD immunoreactive cells. The GABAergic differentiation of pax6-expressing late NPCs into GABA-producing cells was further supported in cortical NPCs primarily cultured from transgenic mouse brains, which express recombinant GFP under the control of pax6 promoter. The results suggest that aucubin can be developed as a therapeutic candidate for neurodegenerative disorders caused by the loss of inhibitory GABAergic neurons.

Change of Kv Channel Interacting Protein 1 and Gamma-Aminobutyric Acid-ergic Neurons in Hippocampus of Pentylenetetrazole Induced Epilepsy Rats / 中国康复理论与实践

@#Objective To explore the role of Kv channel interacting protein 1(KChIP1)in the process of epileptic seizure and the relationship between KChIP1 and gamma-aminobutyric acid-(GABA)ergic neurons.Methods Normal female Sprague-Dawley rats were treated with pentylenetetrazole to make acute pentylenetetrazole models of epilepsy.Laser Scanning Confocal Microscope(LSCM)combined with double-labeled immunohistochemical technique was applied to observe the expression of the KChIP1 and the GABAergic neurons in the hippocampus of rats.Results The number of KChIP1-postive neurons in the hippocampus was significantly increased in the acute pentylenetetrazole model rats(P<0.05).There was no significant difference in the number of double-labled neurons(P>0.05),nor of the GABA-postive neurons between the model rats and the controls.The ratio of double-labeled neurons/total positive neurons was 63.9% in the hippocampus.Conclusion The KChIP1 might be involved in epileptogenesis of pentylenetetrazole induced seizure.The KChIP1 was associated with GABAergic neurons,whereas it may be functionally different from GABA.

The effects of laminin on the characteristics and differentiation of neuronal cells from epidermal growth factor-responsive neuroepithelial cells

Many extracellular matrix molecules are expressed in the embryonic nervous system and there is some evidence that they are important regulators of neural development. Of these molecules, laminin appears to be the most potent, affecting virtually all neurons of the peripheral and central nervous system. This study was undertaken to investigate the effects of laminin on the proliferation and differentiation of cultured neuroepithelial cells taken from fetal rat forebrains (embryonic day 17-19). The results are summarized as follows. 1) Neuroepithelial cells cultivated in epidermal growth factors containing serum-free medium subsequently differentiated into neurons, astrocytes, and oligodendrocytes. 2) Neuronal cells derived from neuroepithelial cells were immunoreactive for gamma-aminobutyric acid (GABA) or substance P, but were not for serotonin and tyrosine hydroxylase. 3) In western blot analysis, the phosphorylated neurofilament content in neuronal cells was higher in culture on laminin than in culture on poly-L-lysine (PLL). 4) The proliferation rate of GABAergic neurons was higher in culture on laminin than in culture on PLL. These results suggest that GABAergic and substance P-ergic neurons can be differentiated from neuroepithelial cells and that laminin promotes the differentiation of neuronal cells from neuroepithelial cells and the increased proliferation rate of GABAergic cells.

Excitotoxic Cell Death in Cultured Retinal Neurons

We examined excitotoxicity, putatively a major mechanism of ischemic neuronal death, in primary rat retinal cultures. Retinal cultures were prepared from newborn rats (day 1 or 2). Exposure of these cultures (DIV8-10)to NMDA or kainate induced neuronal death. Furthermore, MK-801 or CNQX each partially attenuated glutamateinduced neuronal death, suggesting that both NMDA and kainate receptors mediate it. Thy-1(+) retinal ganglion neurons, like neurons as a whole, were equally injured by NMDA and by kainate. However, GABA(+) or calbindin (+) neurons of the inner nuclear layer were resistant to NMDA, but highly vulnerable to kainate. These neurons may have AMPA/kainate receptors that are highly permeable to Ca2+, as they take up cobalt with kainate stimulation. These results suggest that the AMPA/kainate receptor, rater than the NMDA receptor, may mediate this pattern of selective neurnonal death.

AN IMMUNOELECTRON MICROSCOPIC STUDY ON THE SYNAPTIC RELATIONSHIP BETWEEN DOPAMINERGIC AND GABAergic NEURONS IN THE BASOLATERALNUCLEUS OF THE RAT AMYGDALA / 解剖学报

Objective To explore the relationship between dopaminergic axon terminal and GABAergic neurons and explore the neuroanatomic mechanism of their effects in schizophrenia. Methods The co-location and the association of dopaminergic axon terminal and GABAergic neurons in the basolateral nucleus (BL) of rat amygdala were examined by using double labeling immunoelectron microscopic techniques. Dopaminergic axon terminal and GABAergic neurons were labeled with the antidopamine (anti-DA) and the anti-glutamic acid decarboxylase (anti-GAD) antibodies respectively. Results 43% of the DA-input synapses was observed to relate directly or indirectly to GAD-immunoreactive(IR) dendritic structures(DA/GAD), which includes single (38%), convergent (30%), serial (20%), and axoaxonic (12%) contact types.And 57% of the DA-input synapses was found to associate with unlabeled elements (DA/UE), which includes unlabeled perikarya (10%), dendrites (82%) and axons (8%). All of the synapses that show DA-IR terminals profiles were found to be symmetric (inhibitory) synapses.Conclusion These results suggest that the dopaminergic system in the BL of rat amygdala controls the mediations of the GABAergic interneurons via symmetric synapses. In addition, the dopaminergic axon terminal associates with the glutamatergic projection neurons and exerts influence on its activity.