Therefore, these results suggest that alterations in intracellular signaling pathways might be a protective mechanism against DOM induced excitotoxic damage. Ca2 mediated signaling pathways tightly modulate BDNF expression mainly through the transcription fac tor CREB. In conjunction with the observed increase in BDNF and TrkB, http://www.selleckchem.com/products/Tipifarnib(R115777).html DOM insult was found to stimulate activation of CREB in hippocampal cultures. Several studies have proven that CREB activation re quires serine 133 phosphorylation, which can be medi ated by PKA, MAPK pathway or CaMKs, among others, depending on the activating signal and cell type. In the current experiments, inhibitors of both MEK and PKA attenuated the Inhibitors,Modulators,Libraries DOM stimulated activation of CREB as well as upregulation of BDNF.

In contrast, the CaMKII inhibitor failed to prevent or significantly de crease any of the protein changes observed. These data strongly suggest that transient DOM exposure in hippo campal cultured slices upregulates CREB dependent transcription of BDNF by activating the MAPK and PKA pathways rather than the CaMKII Inhibitors,Modulators,Libraries cascade. ERK ac tivation has been previously associated with the tran scription factor CREB in cultured hippocampal Inhibitors,Modulators,Libraries neurons and brain slices and as MAPK signaling is re quired for prolonged CREB phosphorylation, it has been suggested that MAPK signalling might be highly relevant for the activation of CREB dependent transcription. It has also been reported that PKA regula tion of transcription via CREB is implicated in brain plasticity, learning and memory.

Our results showed that the DOM induced increases in BDNF ex pression and CREB phosphorylation were completely blocked with concurrent exposure to PKA and MEK in hibitors. We further explored whether crosstalk between the PKA and ERK pathways might also play a role in the observed activation of CREB following Inhibitors,Modulators,Libraries DOM insult. Al though evidence of coupling between these signaling pathways has been provided previously in vivo and in vitro no Inhibitors,Modulators,Libraries evidence was found in OHSC after DOM insult. namely, the MEK inhibitor PD98059 failed to modulate PKA pathway activation and no significant changes were found in p ERK levels after concurrent exposure to the PKA inhibitor H89 and DOM compared to exposure to DOM alone. Together, these pieces of evidence suggest that the PKA and MEK activated pathways are operating in parallel in this system and converge upon CREB, leading to BDNF overexpression.

An interesting but currently unexplained finding from our experiments was that the DOM induced increase in CaMKII was selleck chem attenuated with MEK inhibition. It has been previously described that CaMKII, as an upstream kinase, interacts with Raf, modulating the activation of ERK proteins but, to our knowledge, there is no previous evidence of ERK acting as an upstream regulator of CaMKII phosphorylation in the CNS.