Abstract
Minocycline has been shown to have remarkably neuroprotective qualities, but underlying mechanisms remain elusive. We reported here the robust neuroprotection by minocycline against glutamate-induced apoptosis through regulations of p38 and Akt pathways. Pre-treatment of cerebellar granule neurons (CGNs) with minocycline (10-100 microm) elicited a dose-dependent reduction of glutamate excitotoxicity and blocked glutamate-induced nuclear condensation and DNA fragmentations. Using patch-clamping and fluorescence Ca2+ imaging techniques, it was found that minocycline neither blocked NMDA receptors, nor reduced glutamate-caused rises in intracellular Ca2+. Instead, confirmed by immunoblots, minocycline in vivo and in vitro was shown to directly inhibit the activation of p38 caused by glutamate. A p38-specific inhibitor, SB203580, also attenuated glutamate excitotoxicity. Furthermore, the neuroprotective effects of minocycline were blocked by phosphatidylinositol 3-kinase (PI3-K) inhibitors LY294002 and wortmannin, while pharmacologic inhibition of glycogen synthase kinase 3beta (GSK3beta) attenuated glutamate-induced apoptosis. In addition, immunoblots revealed that minocycline reversed the suppression of phosphorylated Akt and GSK3beta caused by glutamate, as were abolished by PI3-K inhibitors. These results demonstrate that minocycline prevents glutamate-induced apoptosis in CGNs by directly inhibiting p38 activity and maintaining the activation of PI3-K/Akt pathway, which offers a novel modality as to how the drug exerts protective effects.
Publication types
-
Comparative Study
-
Research Support, Non-U.S. Gov't
MeSH terms
-
Activating Transcription Factor 2
-
Animals
-
Animals, Newborn
-
Apoptosis / drug effects*
-
Blotting, Western / methods
-
Calcium / metabolism
-
Cell Count / methods
-
Cell Survival / drug effects
-
Cells, Cultured
-
Cerebellum / cytology*
-
Chromatin / metabolism
-
Cyclic AMP Response Element-Binding Protein / metabolism
-
DNA Fragmentation / drug effects
-
Dizocilpine Maleate / pharmacology
-
Dose-Response Relationship, Drug
-
Drug Interactions
-
Enzyme Inhibitors / pharmacology
-
Glutamic Acid / pharmacology*
-
Humans
-
Membrane Potentials / drug effects
-
Microscopy, Confocal / methods
-
Minocycline / pharmacology*
-
N-Methylaspartate / pharmacology
-
Neurons / drug effects*
-
Neurons / pathology
-
Neurons / physiology
-
Neuroprotective Agents / pharmacology
-
Patch-Clamp Techniques / methods
-
Protein Serine-Threonine Kinases / metabolism*
-
Proto-Oncogene Proteins / metabolism*
-
Proto-Oncogene Proteins c-akt
-
Rats
-
Rats, Sprague-Dawley
-
Serine / metabolism
-
Signal Transduction / drug effects
-
Tetrazolium Salts / metabolism
-
Thiazoles / metabolism
-
Time Factors
-
Transcription Factors / metabolism
-
p38 Mitogen-Activated Protein Kinases / metabolism*
Substances
-
Activating Transcription Factor 2
-
Chromatin
-
Cyclic AMP Response Element-Binding Protein
-
Enzyme Inhibitors
-
Neuroprotective Agents
-
Proto-Oncogene Proteins
-
Tetrazolium Salts
-
Thiazoles
-
Transcription Factors
-
Glutamic Acid
-
Serine
-
N-Methylaspartate
-
Dizocilpine Maleate
-
AKT1 protein, human
-
Akt1 protein, rat
-
Protein Serine-Threonine Kinases
-
Proto-Oncogene Proteins c-akt
-
p38 Mitogen-Activated Protein Kinases
-
thiazolyl blue
-
Minocycline
-
Calcium