Abstract
Background: Noopept (N-phenylacetyl-L-prolyl-glycine ethyl ester) is approved in Russia as cognition enhancer. To establish the mechanisms responsible for Noopet's neuroptopic effects we have focused on the HIF-1-dependent pathway. Hypoxia-inducible growth factor-1 (HIF-1) is the master regulator of cellular and tissue adaptive responses to low oxygen. Over the past few years, HIF-1 has emerged as a viable target to counteract neurodegeneration, ischemia and cognition deficit in some neurological and neurodegenerative diseases.
Methods: HEK293 and SH-SY5Y cells were transiently transfected by luciferase reporter construct containing hypoxia-response element (HRE-Luc) to monitor the effect on Noopept on HIF-1 transcriptional activity. mRNA levels of HIF-1a gene and HIF-1-regulated genes were evaluated by QRT-PCR; western-blot analysis was applied to detect HIF-1a protein level. The in vitro scratch assay has been used to measure the migration of HUVEC cells treated by deferoxamine followed by Noopept exposure.
Results: We have found Noopept (0.1 mM, 24 hours) as moderate activator of the HRE-Luc reporter, which showed 40% activation over CoCl2 - or deferoxamine-induced HRE-Luc response in HEK293 or SH-SY5Ycells respectively. Insight to mechanisms of HIF-1-positive effects of Noopept revealed an 20 % increase of mRNA for HIF-1a gene in SH-SY5Ycells treated with the compound (0.1 mM, 24 hours) in hypoxia mimicking conditions (deferoxamine, 0.1 mM, 6 hours). Furthermore the elevation of HIF-1a protein level up to 30% was detected under the same experimental circumstances. Accordingly, several HIF-1 - regulated genes such as EPO, VEGF and PDK1 were also induced by Noopept (0.1 mM, 24 hours) upon modeled hypoxic conditions. Data obtained with the in vitro wound healing assay showed that Noopept ameliorated the closing of the scratch edge in HUVEC cells in a time dependent manner more effective than deferoxamine did.
Conclusion: Together these findings suggest that Noopept is interacting with HIF-1 signaling pathway by HIF-1 stabilization, likely through the induction of HIF-1a transcription and translation resulting in increased HIF-dependent gene expression. HIF-1-positive effect of Noopept might contribute to its neurotropic activity.
