Pharmacological Modulation of Three Modalities of CA1 Hippocampal Long-Term Potentiation in the Ts65Dn Mouse Model of Down Syndrome

The Ts65Dn mouse is the most studied animal model of Down syndrome. Past research has shown a significant reduction in CA1 hippocampal long-term potentiation (LTP) induced by theta-burst stimulation (TBS), but not in LTP induced by high-frequency stimulation (HFS), in slices from Ts65Dn mice compared with euploid mouse-derived slices. Additionally, therapeutically relevant doses of the drug memantine were shown to rescue learning and memory deficits in Ts65Dn mice. Here, we observed that 1 mu M memantine had no detectable effect on HFS-induced LTP in either Ts65Dn- or control-derived slices, but it rescued TBS-induced LTP in Ts65Dn-derived slices to control euploid levels. Then, we assessed LTP induced by four HFS (4xHFS) and found that this form of LTP was significantly depressed in Ts65Dn slices when compared with LTP in euploid control slices. Memantine, however, did not rescue this phenotype. Because 4xHFS-induced LTP had not yet been characterized in Ts65Dn mice, we also investigated the effects of picrotoxin, amyloid beta oligomers, and soluble recombinant human prion protein (rPrP) on this form of LTP. Whereas >= 10 mu M picrotoxin increased LTP to control levels, it also caused seizure-like oscillations. Neither amyloid beta oligomers nor rPrP had any effect on 4xHFS-induced LTP in Ts65Dn-derived slices.Alana USA Foundation [124124]Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES)Awakening AngelsNIH [NS083687]Case Western Reserve Univ, Dept Pediat, Div Pediat Neurol, Cleveland, OH 44106 USAUniv Fed Sao Paulo, Cardiol, Postgrad Program Med, BR-04024002 Sao Paulo, SP, BrazilCase Western Reserve Univ, Dept Physiol & Biophys, Cleveland, OH 44106 USACase Western Reserve Univ, Dept Psychiat, Cleveland, OH 44106 USAUniv Fed Sao Paulo, Cardiol, Postgrad Program Med, BR-04024002 Sao Paulo, SP, BrazilCAPES: NS083687Web of Scienc

Cytoprotective Small Compound M109S Attenuated Retinal Ganglion Cell Degeneration Induced by Optic Nerve Crush in Mice

BAX plays an essential role in retinal ganglion cell (RGC) death induced by optic nerve injury. Recently, we developed M109S, an orally bioactive and cytoprotective small compound (CPSC) that inhibits BAX-mediated cell death. We examined whether M109S can protect RGC from optic nerve crush (ONC)-induced apoptosis. M109S was administered starting 5 h after ONC for 7 days. M109S was orally administered in two groups (5 mg/kg twice a day or 7.5 mg/kg once a day). The retina was stained with anti-BRN3A and cleaved Caspase-3 (active Caspase-3) that are the markers of RGC and apoptotic cells, respectively. ONC decreased the number of BRN3A-positive RGC and increased the number of active Caspase-3-expressing apoptotic cells. In ONC-treated retina, there were cells that were double stained with anti-BRN3A and ant-cleaved Caspase-3, indicating that apoptosis in BRN3A-positive RGCs occurred. M109S inhibited the decrease of BRN3A-positive cells whereas it inhibited the increase of active Caspase-3-positive cells in the retina of ONC-treated mice, suggesting that M109S inhibited apoptosis in RGCs. M109S did not induce detectable histological damage to the lungs or kidneys in mice, suggesting that M109S did not show toxicities in the lung or kidneys when the therapeutic dose was used. The present study suggests that M109S is effective in rescuing damaged RGCs. Since M109S is an orally bioactive small compound, M109S may become the basis for a portable patient-friendly medicine that can be used to prevent blindness by rescuing damaged optic nerve cells from death

Brn3a expression is increased in differentiated iPS cells.

<p>RT-qPCR of Brn3a and GAPDH mRNA was performed. (A) Gel electrophoresis of Brn3a and GAPDH expression in undifferentiated and differentiated iPS cells. The PCR products obtained after 34 cycles was run on a 3% agarose gel. (B) The relative Brn3a gene expression in undifferentiated and differentiated iPS cells (unpaired t test, p<0.0004). Data shown are mean ± SEM of three biological replicates.</p

Differentiation of neural progenitor cells to sensory neurons.

<p>(A) Brightfield images of neural progenitor cells on days 2, 8 and 14 in media containing growth factors. (B) Twenty-four days after initiating differentiation of iPS cells, neurons expressed the neuronal marker βIII-tubulin. Nuclei were visualized with DAPI. (C) Approximately 80% of differentiated iPS cells are βIII-tubulin+ as determined by flow cytometry. The red tracing represents unstained cells and the blue tracing represents cells stained with an antibody to βIII-tubulin. (D) Cells also expressed peripherin and Brn3a, markers of sensory neurons. (E) The percentage of peripherin+, Brn3a+, and peripherin+/Brn3a+ cells was determined by flow cytometry. Data shown are the mean ± SEM. Co-expression of Islet-1 with (F) Brn3a and (G) peripherin. Scale for all images is 100 um.</p

Neurons derived from iPS cells support action potentials.

<p>Whole-cell patch-clamp recordings were made in current-clamp mode from the soma of neurons. Shown above are representative traces recorded from one neuron that generated action potentials in response to depolarization. The stimulus protocol is depicted in lower traces. Membrane potentials were recorded from four neurons.</p

HSV infects iPS cells at all stages of differentiation.

<p>Cells were infected with cell-free HSV at a MOI of 0.1 for 96 hours. (A) DAPI staining identifies the iPS cell colonies (highlighted by the dotted white lines). (B) Immunostaining for gD revealed that both iPS cells and the underlying fibroblasts supported HSV infection, as evidenced by abundant gD expression. (C) Merge of panels A and B. (D–F) Sensory neurons derived from iPS cells also supported HSV infection. Staining for gD (D) and Brn3a (E). (F) Merge of panels D and E. Scale for all images is 100 um.</p

Conversion of human iPS cells to neural progenitor cells.

<p>(A) Outline of the differentiation protocol. Human iPS cells were dissociated and plated on Matrigel-coated plates. For the first 10 days, they were exposed to small molecule inhibitors, followed by culturing for two weeks in growth factors. (B) Brightfield images of iPS cells after 4 and 10 days of exposure to small molecule inhibitors. After 10 days, iPS cells expressed (C) Pax6 and (D) nestin, markers of neural progenitor cells. Nuclei were visualized with DAPI. Scale for all images is 100 um.</p