Evidence supporting neuroprotective effect of adipose derived stem cells on PC12 cells against oxidative stress induced by H2O2.

Adipose-derived stem cells (ADSCs) are a population of cells derived from adipose tissue. ADSCs exhibit multilineage development potential and are able to secrete various factors, which influence adjacent cells. The present study examined the protective effect of ADSC's conditioned media (ADSC-CM) on PC12 cells exposed to H2O2, an oxidative injury model. After isolation, ADSCs were cultured and their osteogenic and adipogenic differentiation confirmed. Then, PC12 cells were co-treated with ADSC-CM and H2O2. Next, the effects of ADSC-CM on neurite outgrowth and cell differentiation in the presence of H2O2 were determined. Moreover, cell viability and apoptotic cell death percentage were evaluated using MTT assay, Hoechst staining and flow cytometry. Our results indicated the neuroprotective effects of ADSC-CM on morphological and morphometrical properties of neuron-like PC12 cells. Additionally, the profound decrease in percentage of apoptotic cells confirmed the protective effects of conditioned media from ADSCs that may be related to the release of trophic factors.

Reduction of autophagy markers mediated protective effects of JNK inhibitor and bucladesine on memory deficit induced by Aß in rats.

Autophagy, the process of self-degradation of cellular components, has an important role in neurodegenerative diseases, such as Alzheimer's disease. In this study, we investigated the effects of SP600125 as c-Jun N-terminal kinase (JNK) inhibitor and bucladesine as a cyclic adenosine 3',5'-monophosphate (cAMP) analog on spatial memory and expression of autophagic factors in Aß-injected rats. Male Wistar rats were used. Rats were randomly allocated into five groups as following: amyloid beta (Aß)-only group, Aß + SP600125 (30 µg/1 µ/side, n = 7) and/or bucladesine (100 µM/1 µl/side, n = 7), and the normal control (vehicle only) group. The treatments were administered bilaterally to the CA1 sub-region of the hippocampus stereotaxically. Spatial reference memory was performed using Morris Water Maze 21 days later. The expression of authophagy markers (beclin1, Atg7, Atg12, and LC3 II/LC3 I) in the hippocampus was evaluated using western blotting. Compared to the vehicle group, Aß administration reduced spatial reference learning (P < 0.001) and memory (P < 0.01) and upregulated the expression of beclin1, Atg7, Atg12, and LC3 II/I (P < 0.0001). Compare to Aß-only group, the administration of SP600125 and/or bucladesine improved spatial reference learning (P < 0.001) and memory (P < 0.01). Compared to the Aß-only group, the treatment with SP600125 and/or bucladesine also reduced beclin1, Atg7, Atg12, and LC3 II/I (P < 0.0001) which was similar to amount of normal rats. In summary, it seems that the improvement of spatial memory by SP600125 and/or bucladesine in Aß-injected rats is in relation with normalizing of autophagy to the physiologic level, possibly through neuroprotection and/or neuroplasticity.

Brain mitochondrial ATP-insensitive large conductance Ca⁺²-activated K⁺ channel properties are altered in a rat model of amyloid-ß neurotoxicity.

Mitochondrial dysfunction is a hallmark of amyloid-beta (Aß)-induced neuronal toxicity in Alzheimer's disease (AD). However, the underlying mechanism of how Aß affects mitochondrial function remains uncertain. Because mitochondrial potassium channels have been involved in several mitochondrial functions including cytoprotection, apoptosis and calcium homeostasis, a study was undertaken to investigate whether the gating behavior of the mitochondrial ATP- and ChTx-insensitive-IbTx-sensitive Ca(2+)-activated potassium channel (mitoBKCa) is altered in a rat model of Aß neurotoxicity. Aß1-42 (4 µg/µl) was intracerebroventricularly injected in male Wistar rats (220-250 g). Brain Aß accumulation was confirmed two weeks later on the basis of an immunohistochemistry staining assay, and physiological impacts measured in passive avoidance task cognitive performance experiments. Brain mitochondrial inner membranes were then extracted and membrane vesicles prepared for channel incorporation into bilayer lipid. Purity of the cell fraction was confirmed by Western blot using specific markers of mitochondria, plasma membrane, endoplasmic reticulum, and Golgi. Our results first provide evidence for differences in mitoBKCa ion permeation properties with channels coming from Aß vesicle preparations characterized by an inward rectifying I-V curve, in contrast to control mitoBKCa channels which showed a linear I-V relationship under the same ionic conditions (200 mM cis/50mM trans). More importantly the open probability of channels from Aß vesicles appeared 1.5 to 2.5 smaller compared to controls, the most significant decrease being observed at depolarizing potentials (30 mV to 50 mV). Because BKCa-ß4 subunit has been documented to shift the BKCa channel voltage dependence curve, a Western blot analysis was undertaken where expression of mitoBKCa α and ß4 subunits was estimated using anti-α and ß4 subunit antibodies. Our results indicated a significant increase in mitoBKCa-ß4 subunit expression coupled to a decrease in the expression of α subunit. Our results thus demonstrate a modification in the mitoBKCa channel gating properties in membrane preparations coming from a rat model of Aß neurotoxicity, an effect potentially linked to a change in mitoBKCa-ß4 and -α subunits expression or increased ROS production due to an enhanced Aß mitochondrial accumulation. Our results may provide new insights into the cellular mechanisms underlying mitochondrial dysfunctions in Aß neurotoxicity.