Figure 4. DCS restored CHI-induced reduction in BDNF. A) Sixteen days after CHI, mice were sacrificed, and their brains processed for immu- nohistochemistry as described in the methods. BDNF (a, d, g) and synaptophysin (b, e, h see white arrows) immunoreactivity at the sham- operated (a–c) and injured (d–i) CA1 area (c, f, i the corresponding nuclei of the cells stained with DAPI) in sham (c), CHIVehicle (f) and CHIDCS (i) treated animals. DCS preserved a significantly higher number of BDNF-positive cells following CHI, whereas the reduced syn- aptophysin immunoreactivity was not similarly affected. Histogram depicts the level of fluores- cence intensities of BDNF immunoreactivity in the CA1 hippocampal region of CHIVehicle or CHIDCS treated animals quantified as described in the methods. P 0.0001, 2 test. B) Total homogenates (50 gr/lane) were pre- pared from 16 d old sham (n3), CHIVehicle (n4) and CHIDCS (n4) mice, and resolved on 15% SDS-PAGE. The membranes were probed with anti-BDNF and antitubulin antibodies to control equal protein loading. Histogram depicts the levels of BDNF normalized to tubulin and presented as the mean sem percentage of sham control (*P0.01, 53.99.1%, significantly lower from sham controls, #P0.01, 95.179.1%, signifi- cantly higher from vehicle treated mice, t-test).
injury. Further, TBI induced a remarkable decrease in the presynaptic protein synaptophysin, a synaptic vesi- cle membrane protein that participate in the fusion of synaptic vesicles to the presynaptic membrane (46). However, in DCS injected mice both PPR and the levels of synaptophysin remained unchanged, suggesting that DCS effects are mainly postsynaptic. However, since the magnitude of LTP measured in DCS treated mice did not recover to control sham levels, we cannot exclude the possibility that damage to the presynaptic inputs
contributes to the impaired LTP in CA1, which results in a partial recovery of LTP in DCS injected mice. Further, LTP, as indicated by a change in the fEPSP slope, can occur from several mechanisms, which are NMDAR-independent, and may be augmented by other factors. Therefore, we are currently conducting an in depth investigation to reveal the underlying molecular mechanism by which DCS leads to the recovery of LTP. Brain derived-neurotrophic factor (BDNF) belongs to the neurotrophin family and regulates the survival,
DCS IMPROVES FUNCTIONAL RECOVERY AND LTP IN CHI MICE