A Smoothened receptor agonist is neuroprotective and promotes regeneration after ischemic brain injury

Cell Death Dis. 2014 Oct 23;5(10):e1481. doi: 10.1038/cddis.2014.446.

Abstract

Ischemic stroke occurs as a result of blood supply interruption to the brain causing tissue degeneration, patient disabilities or death. Currently, treatment of ischemic stroke is limited to thrombolytic therapy with a narrow time window of administration. The sonic hedgehog (Shh) signaling pathway has a fundamental role in the central nervous system development, but its impact on neural cell survival and tissue regeneration/repair after ischemic stroke has not been well investigated. Here we report the neuroprotective properties of a small-molecule agonist of the Shh co-receptor Smoothened, purmorphamine (PUR), in the middle cerebral artery occlusion model of ischemic stroke. We found that intravenous administration of PUR at 6 h after injury was neuroprotective and restored neurological deficit after stroke. PUR promoted a transient upregulation of tissue-type plasminogen activator in injured neurons, which was associated with a reduction of apoptotic cell death in the ischemic cortex. We also observed a decrease in blood-brain barrier permeability after PUR treatment. At 14 d postinjury, attenuation of inflammation and reactive astrogliosis was found in PUR-treated animals. PUR increased the number of newly generated neurons in the peri-infarct and infarct area and promoted neovascularization in the ischemic zone. Notably, PUR treatment did not significantly alter the ischemia-induced level of Gli1, a Shh target gene of tumorigenic potential. Thus our study reports a novel pharmacological approach for postischemic treatment using a small-molecule Shh agonist, providing new insights into hedgehog signaling-mediated mechanisms of neuroprotection and regeneration after stroke.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis / drug effects
  • Brain Ischemia / complications
  • Brain Ischemia / drug therapy*
  • Brain Ischemia / pathology*
  • Brain Ischemia / physiopathology
  • Cerebral Cortex / drug effects
  • Cerebral Cortex / pathology
  • Cerebral Cortex / physiopathology
  • Disease Models, Animal
  • Hedgehog Proteins / metabolism
  • Inflammation / pathology
  • Male
  • Mice, Inbred C57BL
  • Morpholines / pharmacology*
  • Morpholines / therapeutic use*
  • Nerve Regeneration / drug effects*
  • Neurons / drug effects
  • Neurons / metabolism
  • Neurons / pathology
  • Neuroprotective Agents / pharmacology
  • Neuroprotective Agents / therapeutic use*
  • Purines / pharmacology*
  • Purines / therapeutic use*
  • Receptors, G-Protein-Coupled / agonists*
  • Receptors, G-Protein-Coupled / metabolism
  • Signal Transduction / drug effects
  • Smoothened Receptor
  • Stroke / complications
  • Stroke / physiopathology
  • Time Factors
  • Tissue Plasminogen Activator / metabolism
  • Up-Regulation / drug effects

Substances

  • Hedgehog Proteins
  • Morpholines
  • Neuroprotective Agents
  • Purines
  • Receptors, G-Protein-Coupled
  • Smo protein, mouse
  • Smoothened Receptor
  • Tissue Plasminogen Activator
  • purmorphamine