Activation of Sonic hedgehog signal by Purmorphamine, in a mouse model of Parkinson's disease, protects dopaminergic neurons and attenuates inflammatory response by mediating PI3K/AKt signaling pathway.

In Parkinson's disease (PD), microglial activation-mediated neuroinflammation is associated with dopaminergic neurons degeneration in the substantia nigra pars compacta. Previous studies that have investigated this neurodegenerative disease have reported that the Sonic hedgehog (SHH) signaling pathway, through inhibiting the inflammatory processes, exerts a beneficial neuroprotective effect. However, the mechanisms underlying the anti­inflammatory and neuroprotective effects of this signaling pathway remain poorly understood. The present study aimed to further investigate these mechanisms in vitro and in vivo. At first, BV2 microglial cells treated with lipopolysaccharide (LPS) were used to induce an inflammatory response. It was observed that the activation of SHH signaling by Purmorphamine attenuated the LPS­induced inflammatory response, increased the expression of transforming growth factor­ß1 through the phosphatidylinositol 3­kinase (PI3K)/AKT serine/threonine kinase (Akt) intracellular signaling pathway and inhibited nuclear receptor subfamily 4 group A member 2, independently of the PI3K/Akt signaling pathway. Furthermore, the blockade of the PI3K/Akt signaling pathway by intranasal administration of LY294002, significantly reduced the SHH­associated neuroprotective effects on dopaminergic neurons, improved motor functions, and increased the microglial activation and inflammatory response in a mouse model of PD induced using 1­methyl­4­phenyl­1,2,3,6­tetrahydropyridine. In conclusion, the data of the present study reported that anti­inflammatory and neuroprotective effects can be obtained in BV2 microglial cells and in a mouse model of PD by successive activation of the SHH and PI3K/Akt signaling pathways.

PPARα Agonist Fenofibrate Ameliorates Learning and Memory Deficits in Rats Following Global Cerebral Ischemia.

Increasing evidence demonstrates that local inflammation contributes to neuronal death following cerebral ischemia. Peroxisome proliferator-activated receptor α (PPARα) activation has been reported to exhibit many pharmacological effects including anti-inflammatory functions. The aim of this study was to investigate the neuroprotective effects of PPARα agonist fenofibrate on the behavioral dysfunction induced by global cerebral ischemia/reperfusion (GCI/R) injury in rats. The present study showed that fenofibrate treatment significantly reduced hippocampal neuronal death, and improved memory impairment and hippocampal neurogenesis after GCI/R. Fenofibrate administration also inhibited GCI/R-induced over-activation of microglia but not astrocytes and prevented up-regulations of pro-inflammatory mediators in hippocampus. Further study demonstrated that treatment with fenofibrate suppressed GCI/R-induced activations of P65 NF-κB and P38 MAPK. Our data suggest that the PPARα agonist fenofibrate can exert functional recovery of memory deficits and neuroprotective effect against GCI/R in rats via triggering of neurogenesis and anti-inflammatory effect mediated by inhibiting activation of P65 NF-κB and P38 MAPK in the hippocampus, which can contribute to improvement in neurological deficits.

Valproic acid alleviates memory deficits and attenuates amyloid-ß deposition in transgenic mouse model of Alzheimer's disease.

In the brains of patients with Alzheimer's disease (AD) and transgenic AD mouse models, astrocytes and microglia activated by amyloid-ß (Aß) contribute to the inflammatory process that develops around injury in the brain. Valproic acid (VPA) has been shown to have anti-inflammatory function. The present study intended to explore the therapeutic effect of VPA on the neuropathology and memory deficits in APPswe/PS1ΔE9 (APP/PS1) transgenic mice. Here, we report that VPA-treated APP/PS1 mice markedly improved memory deficits and decreased Aß deposition compared with the vehicle-treated APP/PS1 mice. Moreover, the extensive astrogliosis and microgliosis as well as the increased expression in interleukin-1ß (IL-1ß) and tumor necrosis factor-α (TNF-α) in the hippocampus and cortex of APP/PS1 transgenic mice were significantly reduced following administration of VPA, which attenuated neuronal degeneration. Concomitantly, VPA alleviated the levels of p65 NF-κB phosphorylation and enhanced the levels of acetyl-H3, Bcl-2, and phospho-glycogen synthase kinase (GSK)-3ß that occurred in the hippocampus of APP/PS1 transgenic mice. These results demonstrate that VPA could significantly ameliorate spatial memory impairment and Aß deposition at least in part via the inhibition of inflammation, suggesting that administration of VPA could provide a therapeutic approach for AD.

[Changes of Smoothened expression during retinofugal pathway development in mouse embryos].

OBJECTIVE: To examine the change of Smoothened (Smo) expression in the retinofugal pathway and in the growth cones during the period of embryonic day 13 (E13) to E15. METHODS: Smo expression in the chiasm and growth cones was observed by fluorescent immunostaining and retinal explant culture. RESULTS: On E13 and E14, Smo was expressed moderately in the retina and optic disc, and in the corner of the retina, Smo expression was especially dense. On E13, Smo expression was detected in the optic nerves and ventral diencephalon, but only in the superficial region of the optic tract on E14. Smo was also detected in the stem and filopodia of the growth cones in the retinal explant culture during this period. CONCLUSION: Smo expression changes in different developmental phases, suggesting that Smo might play a role in signal optic axon growth during the development of the retinofugal pathway.