Summary of membrane properties of DG granule cells in different groups.

<p>Values are mean ± SEM. One way ANOVA showed no significant difference between different groups.</p><p>Summary of membrane properties of DG granule cells in different groups.</p

CCBs preserve normal R_in against EC-Aβ in the granule cells.

<p>A, R_in was significantly decreased in the granule cells from Aβ treated rats compared to the control group. Treatment by istradipine and nimodipine preserved R_in against Aβ. B, R_in of granule cells in presence of synaptic blockers (CNQX; 10 μM, APV; 50 μM and bicuculline; 20 μM) in different groups. Values are mean ± SEM. *p < 0.05 and ***p < 0.001 compared to the control group, ^#p < 0.05, ^###p < 0.001 contrasted to the EC-Aβ group. Control group, n = 15 cells/ 6 rats; EC-Aβ group, n = 15 cells/ 8 rats; EC-Aβ + ISR, n = 10 cells/ 6 rats; EC-Aβ + NIM, n = 7 cells/ 5 rats.</p

Changes of excitability of granule cells following treatment with Aβ and the protective effect of CCBs.

<p>A, a small current injection was sufficient to evoke an AP in the control granule cells, but not in the EC-Aβ cells. B, the current required to evoke minimal AP firing in EC-Aβ granule cells (right panel) evoked strong AP firing in the control cells (left panel). C, the minimal current to evoke one AP during one second (rheobase current) is increased in the EC-Aβ granule cells compared to the control group. Treatment with calcium channel blockers, isradipine and nimodipine, preserved rheobase current in the EC-Aβ granule cells. D and E, the rheobase related to the R_in in the control and granule cells from Aβ treated rats, respectively. Note different y and x axis scales in these panels. Values are mean ± SEM. ***p < 0.001 compared to the control group and ^##p < 0.01 compared to the EC-Aβ group. Control group, n = 15 cells/ 6 rats; EC-Aβ group, n = 15 cells/ 8 rats; EC-Aβ + ISR, n = 10 cells/ 6 rats; EC-Aβ + NIM, n = 7 cells/ 5 rats.</p

Excitatory neurotransmission onto the dentate gyrus granule cells is reduced in the granule cells from Aβ treated rats.

<p>A, Spontaneous EPSCs were less frequent in the EC-Aβ (lower trace) than control (upper trace) neurons with unaltered kinetics. Far right panel shows the analysis of the time constant of rise and decay phases and examples of sEPSCs traces of granule cells from control and Aβ treated groups which were best fit with single exponential function. Cumulative probability plot (B) and mean amplitude (C) of spontaneous EPSCs were unaltered. D, cumulative probability plots showed that spontaneous events in the EC-Aβ neurons shifted to longer inter-event intervals (IEIs) (lower frequencies). E, Daily i.c.v. treatment by nimodipine produced a significant trend (p = 0.07) towards reversing decreased sEPSCs frequency (2.569 ± 0.25 Hz, n = 6 cells/4 rats) (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0117555#pone.0117555.g001" target="_blank">Fig. 1D and E</a>). Values are mean ± SEM. **p < 0.01 and ***p < 0.001 contrasted to the control cells. Control and EC-Aβ group, n = 6 cells/ 5 rats; EC-Aβ + ISR and EC-Aβ + NIM, n = 6 cells/ 4 rats.</p

Firing properties of dentate gyrus granule cells in response to ramp currents.

<p>A, representative spike firings of DG granule cells in response to ramp current clamp. Aβ microinjection into the EC induced: a significant increase in latency of the first AP (B), a significant increase of current required to evoke the first AP (C), and a significant decrease in AP numbers (D). Treatment by isradipine and nimodipine preserved granule cells from these changes. *p < 0.05 and **p < 0.01 compared with the control cells. ^#p < 0.05 and ^##p < 0.01 compared to the EC-Aβ group. Control and EC-Aβ groups, n = 6 cells/ 4 rats; EC-Aβ + ISR, n = 5 cells/ 4 rats; EC-Aβ + NIM, n = 6 cells/ 4 rats.</p

Surface tension changes for various forms of insulin showing the extent of surface tension of solutions containing insulin with native, oligomer intermediates, proto-fibril, and fibril structures at the air-water interface.

<p>Data represent the average of decuple measurements and error bars represent standard deviation (SD). *Significantly different from native insulin. Statistical significances were achieved when p<0.05.</p

The effects of oligomer, proto-fibril and fibril forms of insulin on neurite complexity in differentiated PC12 cells.

<p>The criteria were quantified 12 h after treatment; <b>A</b>) primary neurites per cell; <b>B</b>) percent of bipolar cells and <b>C</b>) the ratio of nodes to primary neurites. * Significantly different from control cells. Statistical significances were achieved when p<0.05 (*p<0.05 and **p<0.01).</p

Firing properties of DG granule cells evoked by current injections.

<p>A, Aβ pathogenesis in the EC produced changes in firing pattern and decreased firing rate of DG granule cells at different current injections. Co-treatment with calcium channel blockers, isradipine or nimodipine, almost restored the normal firing pattern. B, Number of action potentials evoked at different current steps from 50 to 300 pA with intact synaptic transmission. C, Number of action potentials evoked at different current injections after synaptic transmission blockade in the presence of CNQX; 10 μM, APV; 50 μM and bicuculline; 20 μM, the difference of AP numbers still remained between the control and EC-Aβ cells. Values are mean ± SEM. *p < 0.05, **p < 0.01 and ***p < 0.001 contrasted to control cells, ^##p < 0.01 and ^###p < 0.001 compared to EC-Aβ group. Control group, n = 12 cells/ 6 rats; EC-Aβ group, n = 12 cells/ 8 rats; EC-Aβ + ISR, n = 10 cells/ 6 rats; EC-Aβ + NIM, n = 7 cells/ 5 rats.</p

The effects of oligomer, proto-fibril and fibril forms of insulin on neurite outgrowth in differentiated PC12 cells.

<p><b>A</b>) The criteria of PC12 differentiation are shown on three neurons (left image) of a sample image. The “P” on right image indicates the primary neuritis of a neuron. The yellow arrow shows the length of a neurite, extent elongated, and membrane-enclosed protrusions of cytoplasm. The blue circle on right image shows the cell body. Neurite width is not equal in all parts of neurons, thus the average neurite width must be calculated by dividing cell body area to average neurite length. The white arrows show to bipolar cells. The letter “N” indicates the nodes, the sites at which individual neurites branched or separate neurites contacted each other. The criteria were quantified 12 h after treatment; <b>B</b>) NGF-differentiated PC12 cells were pretreated with three amyloid intermediate forms of insulin. C) Cell body area; D) average neurite length; and E) average neurite width. *Significantly different from control cells. Statistical significances were achieved when p<0.05 (*p<0.05 and **p<0.01).</p

Calcium channel blockers, isradipine and nimodipine, prevent abnormalities in spontaneous IPSCs of DG granule cells caused by amyloid pathology in the EC.

<p>A, amplitude of spontaneous IPSCs increased in the EC-Aβ (lower trace) in contrast with the control (upper trace) neurons and there is a significant decrease in monoexponential decay time constant (fast inactivated) compared to the control cells (right plot, p < 0.05). B, cumulative probability plots showed that spontaneous events in the granule cells from Aβ treated rats shifted to larger amplitude (**p = 0.004 by Kolmogorov–Smirnoff test) and the change was blocked by isradipine and nimodipine. C, the amplitude of sIPSC significantly increased in granule cells from Aβ treated rats compared to the control, and isradinpine and nimodipine blocked the change. Cumulative probability plot (D) and mean frequency of spontaneous IPSCs (E) were unaltered between groups. Values are mean ± SEM. ***p < 0.001 contrasted to the control cells, ^##p < 0.01 and ^#p < 0.05 compared to EC-Aβ group. Control group, n = 6 cells/ 4 rats; EC-Aβ group, n = 8 cells/ 6 rats; EC-Aβ + ISR and EC-Aβ + NIM, n = 6 cells/ 4 rats.</p