Spinal Dorsal Root Ganglion Cells Research Articles

Effects of Hirudin on High Glucose-Induced Oxidative Stress and Inflammatory Pathway in Rat Dorsal Root Ganglion Neurons.

To investigate protective effects of hirudin on oxidative stress and apoptosis of spinal dorsal root ganglion cells in high-glucose rats at the cellular and molecular level. Dorsal root ganglion neurons (DRGn) were harvested from embryonic day in 15 SD rats, purified and identificated after primary culture. They were divided into the normal control group, high-glucose (HG) group, positive control (alpha-lipoic acid, ALA) group, low-dose hirudin group (H1), medium-dose hirudin group (H2) and high-dose hirudin group (H3). The control group was cultured by neuron specific culture medium, while the HG group was cultured by neuron specific culture medium and 20 mmol/L glucose (HG medium). The hirudin groups were cultured by HG medium+0.25 IU/mL hirudin (H1), HG medium+0.5 IU/mL hirudin (H2) and HG medium+1 IU/mL hirudin (H3). The ALA group was cultured by HG medium+100 µ mol/L ALA. 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenylt etrazolium bromide (MTT) assay was used to explore the optimum concentration and intervention time. Flow cytometry assay was used to detect the level of reactive oxygen series (ROS). Western blot and quantificational realtime polymerase chain reaction (qRT-PCR) were used to detect the expression of protein and mRNA of nuclear factor erythroid 2-related factor 2 (Nrf-2), hemeoxygence-1 (HO-1), nuclear factor-κ B (NF-κ B) and Caspase-3. TUNEL assay was used to test the apoptosis rate of different groups. After 24 h of culture, the cell activity of hirudin and ALA groups were higher than that of HG group, and there was a statistical difference between the H1 group and HG group (P<0.05). In hirudin groups, the apoptosis rate of cells, the expression of activated Caspase-3 protein and Caspase-3 mRNA were lower than those of HG group (P<0.01), higher than those of ALA group (P<0.01 or P<0.05). The ROS level of hirudin groups was higher than that of ALA group (P<0.01), lower than that of HG group (P<0.01 or P<0.05). The expression of NF-κ B (P65) protein in H3 group were lower than those of HG group (P<0.05). The expression of Nrf-2 protein in hirudin groups was higher than that of HG group (P<0.01), lower than that of ALA group (P<0.01 or P<0.05). The expression of HO-1 protein in hirudin groups was lower than that of ALA group (P<0.01 or P<0.05), higher than that of HG group (P<0.01 or P<0.05). The activity of DRGn cells can be promoted by hirudin under HG conditions. The effects of hirudin on the inhibition of HG on DRGn cells damage mainly include scavenging ROS, up-regulating Nrf-2/HO-1 pathway, inhibiting activation of NF-κ B pathway, down-regulating the expression of and Caspase-3 and reducing DRGn cell apoptosis.

Effects of honokiol on activation of transient receptor potential channel in rat spinal dorsal root ganglion cells and pruritus in mouse models

Objective To evaluate the effect of honokiol on the activation of transient receptor potential (TRP) channel in rat spinal dorsal root ganglion cells and pruritus in mouse models. Methods Healthy male ICR mice aged 4-6 weeks were used to establish histamine-induced and acetone/ether/water (AEW) -induced itching models separately. Totally, mice were randomly divided into 7 groups (histamine-induced model experiment) or 6 groups (AEW-induced model experiment) : normal control group and model group both gavaged with sodium chloride physiological solution, solvent group gavaged with sodium carboxymethylcellulose solution, chlorphenamine group (only set up in the histamine-induced model experiment) gavaged with chlorphenamine, 50, 25 and 12.5 mg/kg honokiol groups gavaged with 50, 25 and 12.5 mg/kg honokiol respectively. In the histamine-induced model experiment, the mice were all injected with histamine except the normal control group injected with sodium chloride physiological solution 24 hours after the gavage treatment, while the mice in the AEW-induced model experiment were all topically treated with AEW except the normal control group topically treated with sodium chloride physiological solution for 4 days, followed by gavage with different drugs. The anti-itch effect of each treatment was evaluated by counting the scratching frequency within 30 minutes. Rat spinal dorsal root ganglion (DRG) cells were isolated and subjected to a primary culture. Then, the DRG cells were divided into 6 groups: capsaicin or allyl isothiocyanate (AITC) -induced model group pre-incubated with Hank′s balanced salt solution (HBSS) , 500 μmol/L capsazepine or 10 μmol/L HSC030031 group pre-incubated with capsazepine or HSC030031, solvent group pre-incubated with dimethyl sulfoxide (DMSO) , 3 honokiol groups pre-incubated with 7.81, 15.63 and 31.25 mg/L honokiol respectively, and Ca2+ fluorescence imaging system was used to observe changes of Ca2+ influx in these cells after capsaicin or AITC stimulation. Statistical analysis was carried out with SPSS 20.0 software by using one-way analysis of variance and Dunnett-t test. Results In the histamine-induced mouse models, the scratching frequency was significantly lower in the 50 and 25 mg/kg honokiol groups than in the model group (21.88 and 21.14 vs. 63.70, t=3.48, 3.49 respectively, both P=0.003) , while no significant difference in the scratching frequency was observed between the 12.5 mg/kg honokiol group and the model group (t=2.01, P=0.062) . After the treatment with 50 mg/kg honokiol in the AEW-induced mouse models, the scratching frequency significantly decreased compared with the model group (61.4 vs. 101.17, t=0.45, P=0.009) , while there were no significant differences among the 25, 12.5 mg/kg honokiol groups and the model group (all P > 0.05) . Compared with the capsaicin or AITC-induced model group, the increase of Ca2+ fluorescence signal in the DRG cells was significantly inhibited in the 31.25 mg/L honokiol group: at the 45th second, the rate of relative fluorescence intensity change (ΔF/F0) was 1.11 in the model group, but-0.11 in the 31.25 mg/L honokiol group in the capsaicin-induced model experiment, and 0.56 in the model group, but 0.00 in the 31.25 mg/L honokiol group in the AITC-induced model experiment. Conclusion Honokiol shows an inhibitory effect on mouse models of pruritus induced by histaminergic or non-histaminergic factors, likely by inhibiting Ca2+ influx through activated TRPV1 and TRPA1 channels in the DRG cells. Key words: Pruritus; Honokiol; Transient receptor potential channels; Disease models, animal

Lesions of the Central Nervous System Induced by Intracerebral Inoculation of BALB/c Mice with Rabies Virus (CVS-11)

BALB/c mice were inoculated intracerebrally with fixed rabies virus (CVS-11) and pathomorphological changes in the central nervous system were studied. Infected mice showed ruffled hair, hunchback, anorexia, emaciation and ataxia at 5 days postinoculation (DPI), but paralysis did not occur. Viral antigens were first detected in the pyramidal cells of the cerebral cortex and hippocampus at 3 DPI, and these cells exhibited apoptosis at 5 DPI. Microglial cells and astroglial cells significantly increased in the areas of the nerve cells which showed apoptosis. However, spinal neurons and spinal dorsal root ganglion cells did not exhibit apoptosis despite virus infection. These observations indicate that different mechanism which causes apoptosis exists among the neurons of the brain and spinal cord, and glial cells play an important role in pathogenesis of the experimental rabies.

Properties of somata of spinal dorsal root ganglion cells differ according to peripheral receptor innervated.

1. Intracellular recordings were made in the somata of dorsal root ganglion cells in the L7 or S1 DRG in cats anesthetized with alpha-chloralose. The properties of the action potentials (amplitude, duration, peak rate of rise), duration of afterhyperpolarization (AHP), magnitude of inward rectification, and axonal conduction velocity were measured. The adequate stimulus was determined, and the extent to which these properties are correlated was investigated. 2. All cells with receptive fields could be classified as mechanoreceptors. Most cells with A-beta-axons (greater than 36 m/s) could be activated by gentle mechanical stimulation but a small minority with conduction velocity in the low end of the A-beta-range were nociceptors. Cells with A-delta-axons (2-36 m/s) innervated either the very sensitive Down hair follicles (D-hairs) or high-threshold mechanoreceptors (HTMRs). In addition a group of A-delta-fibers was found for which no receptive field could be described. Their spikes, AHPs, and membrane properties were indistinguishable from those of cells supplying HTMRs (see below) and they were lumped together with A-delta-HTMRs. 3. A-beta-neurons exhibited smaller, briefer spikes than A-delta-neurons, even those supplying D-hairs. Peak rate of rise (dV/dt)max and inward rectification were significantly larger in A-beta-cells than in A-delta s, whereas AHP duration and input resistance were smaller. However, the values of these parameters in cells of a given conduction velocity range were generally associated with receptor type. 4. A-delta-HTMRs exhibited spikes of greater amplitude and duration, longer AHP duration, and smaller inward rectification than D-hairs. The long duration of these spikes was due largely to a prominent hump on their descending limb. Input resistance was similar in both groups of cells. 5. A-beta-HTMRs differed from A-beta-cells innervating low threshold receptors in the same general way that A-delta-HTMRs differed from D-hairs. However, A-beta-LTMRs supplying different receptor types (e.g., slowly adapting type I, Pacinian corpuscles, etc.) exhibited no correlation between receptor type and electrophysiology of the soma. 6. These differences in spike parameters occur at the level of the membrane rather than in the degree of somal invasion because the largest amplitude spikes also exhibited the slowest time course (i.e., in HTMRs). Systematic variation in AHP duration and inward rectification also suggest differences in the proportions of ionic channel types among these cells.(ABSTRACT TRUNCATED AT 400 WORDS)