Role of autophagy in nerve cell apoptosis in mice infected with street rabies virus

The Mechanism of Aerobic Exercise Regulating the PI3K/Akt-mTOR Signaling Pathway Intervenes in Hippocampal Neuronal Apoptosis in Vascular Dementia Rats

BACKGROUND

The purpose of this paper is to explore the mechanism of aerobic exercise regulating autophagy through the PI3K/Akt-mTOR signaling pathway and its participation in apoptosis, to protect the hippocampal nerves from damage in vascular dementia rats.

METHODS

Thirty-six healthy male SD rats were randomly divided into a sham group, a model group, and a model exercise group. A neurobehavioral assessment was used to determine the memory and exploration abilities of the rats. A TUNEL assay was used to detect hippocampal neuron apoptosis. Immunohistochemical and Western blot analyses were used to analyze LC3Ⅱ and the beclin-1 protein. An RT-PCR detected the differential expression of mRNA.

RESULTS

The results of the neurobehavioral tests showed that the platform latency time of the rats with vascular dementia was prolonged. Aerobic exercise significantly shortens the swimming time of rats in platform latency. The TUNEL results showed that the TUNEL-positive cells of the hippocampal neurons in the model group increased; the expression of pro-apoptotic genes caspase-3 and Bax mRNA was up-regulated, and the expression of Bcl-2 mRNA was down-regulated. Aerobic exercise reduced hippocampal neuronal apoptosis, up-regulated Bcl-2 mRNA, and down-regulated caspase-3 and Bax mRNA. The LC3Ⅱ and Beclin-1 proteins, detected by immunohistochemistry and a Western blot analysis, showed that the protein expression in the hippocampi of rats with vascular dementia increased. Aerobic exercise reduced LC3Ⅱ and Beclin-1 protein expression. The results of the RT-PCR showed similar changes.

CONCLUSIONS

Aerobic exercise could improve the learning and memory abilities of vascular dementia rats, moderately regulate the process of autophagy, reduce the TUNEL-positive cells of hippocampal neurons, repair damaged hippocampal neurons by regulating the autophagy signaling pathway PI3K/Akt-mTOR, and improve hippocampal function.

Progress in the Mechanism of Autophagy and Traditional Chinese Medicine Herb Involved in Dementia

Dementias is a kind of neurodegenerative disease, which occurs among the aging population. Current therapeutic outcome for dementia is limited. The medical use of herbal plant has a rich history in traditional Chinese medicine practice for thousands of years. Herbal medicine (HM) may provide a positive effect for prevention and treatment in dementia. As an alternative treatment to dementia, there has been a growing interest in HM extracts in scientific community as a result of its promising study results, mainly in animal experiment. At the molecular level, HM extracts trigger autophagy and reduce generation of reactive oxygen species (ROS) while inhibiting inflammation and reduce neurotoxicity. Experiments both in vivo and in vitro have identified certain potential of HM extracts and natural products as an important regulator factor in mediating autophagy, which might contribute to the improvement of dementia. This brief review not only summarizes the mechanism of autophagy in dementia but also offers a general understanding of the therapeutic mechanism of HM extracts in treating dementia and evaluates the potential clinical practice of HM in general.

Enhancement of immune responses by co-stimulation of TLR3 - TLR7 agonists as a potential therapeutics against rabies in mouse model

Rabies is always fatal, when post-exposure prophylaxis is administered after the onset of clinical symptoms. To date, there is no effective treatment of rabies once clinical symptoms has initiated. Therefore, we aimed to provide evidences which indicate the promising effects of combination treatment with TLR agonists following rabies infection. Four groups of rabies infected-mice (10-mice/group) were treated with PolyI:C 50 μg (a TLR3 agonist), Imiquimod50 μg (a TLR7 agonist), (Poly + Imi)25 μg and (Poly + Imi)50 μg respectively. The immune responses in each experimental groups were investigated in the brain through evaluation of GFAP, MAP2, CD4, HSP70, TLR3, TLR7 and apoptotic cell expression as well as determination of IFN-γ, TNF-α and IL-4, levels. The treatment with combination of agonists (Poly + Imi)50 μg/mouse resulted a 75% decrease of mortality rate and better extended survival time following street rabies virus infection. Higher number of CD4⁺T cells, TLR3 and TLR7 expression in the brain parenchyma observed in the groups receiving both combined agonist therapies at the levels of 25 μg and 50 μg. In spite of decreased number of neuronal cell, significant higher number of astrocytes was shown in the group given (Poly + Imi)25 μg. The obtained results also pointed to the dramatic decrease of HSP70 expression in all groups of infected mice whereas higher number of apoptotic cells and Caspase 8 expression were recorded in (Poly + Imi)25 μg treated group. Furthermore, the cytokine profile consisting the increased levels of TNF-α, IFN-γ and IL-4 revealed that both humoral and cellular responses were highly modulated in combination therapy of 50 μg of Imiquimod and Poly I:C. Reduced viral load as quantified by real-time PCR of rabies N gene expression in the brain also correlated with the better survival of agonist-treated groups of mice. Based on obtained results, we have presented evidences of beneficial utilization of combined agonist therapy composed of TLR3/TLR7 ligands. This treatment regimen extended survival of infected mice and decreased significantly their mortality rate. We believe that the results of synergy-inducing protection of both TLR3/TLR7 agonists lead to the enhancement of innate immune responses cells residing in the CNS which warrant the studies to further understanding of crosstalk mechanisms in cellular immunity against rabies in the future.