Baclofen mediates neuroprotection on hippocampal CA1 pyramidal cells through the regulation of autophagy under chronic cerebral hypoperfusion

Sci Rep. 2015 Sep 28:5:14474. doi: 10.1038/srep14474.

Abstract

GABA receptors play an important role in ischemic brain injury. Studies have indicated that autophagy is closely related to neurodegenerative diseases. However, during chronic cerebral hypoperfusion, the changes of autophagy in the hippocampal CA1 area, the correlation between GABA receptors and autophagy, and their influences on hippocampal neuronal apoptosis have not been well established. Here, we found that chronic cerebral hypoperfusion resulted in rat hippocampal atrophy, neuronal apoptosis, enhancement and redistribution of autophagy, down-regulation of Bcl-2/Bax ratio, elevation of cleaved caspase-3 levels, reduction of surface expression of GABAA receptor α1 subunit and an increase in surface and mitochondrial expression of connexin 43 (CX43) and CX36. Chronic administration of GABAB receptors agonist baclofen significantly alleviated neuronal damage. Meanwhile, baclofen could up-regulate the ratio of Bcl-2/Bax and increase the activation of Akt, GSK-3β and ERK which suppressed cytodestructive autophagy. The study also provided evidence that baclofen could attenuate the decrease in surface expression of GABAA receptor α1 subunit, and down-regulate surface and mitochondrial expression of CX43 and CX36, which might enhance protective autophagy. The current findings suggested that, under chronic cerebral hypoperfusion, the effects of GABAB receptors activation on autophagy regulation could reverse neuronal damage.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis / drug effects
  • Autophagy / drug effects
  • Baclofen / pharmacology*
  • Biomarkers
  • Brain Ischemia / drug therapy
  • Brain Ischemia / genetics
  • Brain Ischemia / metabolism*
  • CA1 Region, Hippocampal / drug effects*
  • Caspase 3 / metabolism
  • Cell Membrane / metabolism
  • Connexin 43 / genetics
  • Connexin 43 / metabolism
  • Connexins / genetics
  • Connexins / metabolism
  • Disease Models, Animal
  • Gap Junction delta-2 Protein
  • Gene Expression
  • Glycogen Synthase Kinase 3 / metabolism
  • Glycogen Synthase Kinase 3 beta
  • Male
  • Mitochondria / metabolism
  • Mitogen-Activated Protein Kinase 1 / metabolism
  • Mitogen-Activated Protein Kinase 3 / metabolism
  • Neuroprotection / drug effects*
  • Phosphorylation
  • Proto-Oncogene Proteins c-akt / metabolism
  • Pyramidal Cells / drug effects*
  • Pyramidal Cells / metabolism*
  • Rats
  • Receptors, GABA-A / genetics
  • Receptors, GABA-A / metabolism

Substances

  • Biomarkers
  • Connexin 43
  • Connexins
  • Receptors, GABA-A
  • Glycogen Synthase Kinase 3 beta
  • Gsk3b protein, rat
  • Proto-Oncogene Proteins c-akt
  • Mitogen-Activated Protein Kinase 1
  • Mitogen-Activated Protein Kinase 3
  • Glycogen Synthase Kinase 3
  • Caspase 3
  • Baclofen