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Objective:To evaluate the role of spinal peroxisome proliferation-activated receptor-γ (PPAR-γ) in protectin D1 (PD1)-induced reduction of neuropathic pain (NP) in rats.Methods:Forty-eight clean-grade healthy male Sprague-Dawley rats, aged 6-8 weeks, weighing 200-250 g, were divided into 4 groups ( n=12 each) by a random number table method: sham operation group (Sham group), NP group, NP plus PD1 group (NP+ PD group), and NP plus PD1 plus GW9662 group (NP+ PD+ GW group). Neuropathic pain was induced by spared nerve injury in anesthetized rats.In NP+ PD and NP+ PD+ GW groups, PD1 900 ng (diluted to 20 μl in dimethyl sulfoxide [DMSO]) was intrathecally injected once a day for 8 consecutive days starting from 30 min before establishing the model.In NP+ PD+ GW group, the PPAR-γ antagonist GW9662 200 ng (diluted to 20 μl in DMSO) was intrathecally injected once a day for 8 consecutive days starting from 45 min before establishing the model.The equal volume of DMSO was intrathecally injected in Sham group.The mechanical paw withdrawal threshold (PWT) was measured before establishing the model and at 1, 3, 5, 7, 10 and 14 days after establishing the model.Six rats in each group were sacrificed on day 14 after establishing the model, and their lumbar enlargements were removed for determination of the expression of PPAR-γ, TNF-α and IL-6 by Weston blot.Six rats in each group were sacrificed on day 14 after establishing the model, L 4, 5 segments of the spinal cord were removed, and the co-expression of PPAR-γ with neuron-specific nucleoprotein (NeuN), glial fibrillary acidic protein (GFAP) or serum calcium binding adapter molecule 1 (Iba-1) was determined by immunofluorescence staining. Results:Compared with group Sham, PWT was significantly decreased at each time point after establishing the model, the expression of PPAR-γ was down-regulated, and the expression of TNF-α and IL-6 was up-regulated in the other three groups ( P<0.05). Compared with group NP, PWT was significantly increased at 7-14 days after establishing the model, the expression of PPAR-γ was up-regulated, and the expression of TNF-α and IL-6 was down-regulated in group NP+ PD, and no significant change was found in the parameters mentioned above in group NP+ PD+ GW ( P>0.05). Compared with group NP+ PD, PWT was significantly decreased at 7-14 days after establishing the model, the expression of PPAR-γ was down-regulated, and the expression of TNF-α and IL-6 was up-regulated in group NP+ PD+ GW ( P<0.05). The results of immunofluorescence staining of the spinal cord showed that PPAR-γ was co-expressed with NeuN and GFAP. Conclusion:The mechanism by which PD1 mitigates NP is related to promoting the activation of PPAR-γ in spinal cord neurons and astrocytes and inhibiting inflammatory responses in rats.
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Objective To study the pathological alterations,such as oxidative stress,cell proliferation and insulin resistance,especially autophagy,in Alzheimer' s disease (AD) complicated with type 2 diabetes (AD + T2DM).Methods The mouse models of T2DM,AD and AD + T2DM were used in the study,and totally 80 mice were divided into four groups:control group,T2DM group,AD group and AD + T2DM group.Morris water maze was applied to test the ability of learning and memory among the above mentioned groups.In the meantime,insulin resistance index,the expression of insulin receptor substrate 2,oxidative stress,cell proliferation and autophagy were observed with chemical analysis,immunofluorescent labeling,transmission electron microscopy and Western blotting.Results On day 4,the difference of time to find Morris water maze in control group,T2DM group,AD group and AD + T2DM group ((26.08 ±4.93) s,(38.46 ± 4.07) s,(47.32 ± 5.86) s,(53.01 ± 6.12) s,F =2.454,P =0.025) was statistically significant,and the time in AD + T2DM group was longer than that in AD group (t =-3.624,P =0.033).Compared with control group,insulin resistance occurred in T2DM group,AD group and AD + T2DM group (4.35 ± 0.48,16.12 ± 3.57,7.03 ± 3.11,18.78 ± 5.06,F =5.602,P =0.009),and the reduction of insulin receptor substrate 2 expression,the oxidative stress reaction,neural proliferative suppression and autophagy (F =418.344,222.514,436.250,113.934,23.772,35.469,all P ＜ 0.05) were induced in T2DM group,AD group and AD + T2DM group,which were more serious in AD + T2DM group than in AD group (t =-2.796,21.723,-8.041,9.037,-4.403,-32.011,-26.593,all P ＜0.05).Conclusion AD + T2DM mice suffered more serious cognitive impairment than AD and T2DM mice.The oxidative stress levels of AD + T2DM mice were upregulated,and thus led to the inhibition of cell proliferation,eventually leading to promotion of autophagy.