Blockade of Acid-Sensing Ion Channels Attenuates Recurrent Hypoglycemia-Induced Potentiation of Ischemic Brain Damage in Treated Diabetic Rats

Neuromolecular Med. 2019 Dec;21(4):454-466. doi: 10.1007/s12017-019-08546-6. Epub 2019 May 27.

Abstract

Diabetes is a chronic metabolic disease and cerebral ischemia is a serious complication of diabetes. Anti-diabetic therapy mitigates this complication but increases the risk of exposure to recurrent hypoglycemia (RH). We showed previously that RH exposure increases ischemic brain damage in insulin-treated diabetic (ITD) rats. The present study evaluated the hypothesis that increased intra-ischemic acidosis in RH-exposed ITD rats leads to pronounced post-ischemic hypoperfusion via activation of acid-sensing (proton-gated) ion channels (ASICs). Streptozotocin-diabetic rats treated with insulin were considered ITD rats. ITD rats were exposed to RH for 5 days and were randomized into Psalmotoxin1 (PcTx1, ASIC1a inhibitor), APETx2 (ASIC3 inhibitor), or vehicle groups. Transient global cerebral ischemia was induced overnight after RH. Cerebral blood flow was measured using laser Doppler flowmetry. Ischemic brain injury in hippocampus was evaluated using histopathology. Post-ischemic hypoperfusion in RH-exposed rats was of greater extent than that in control rats. Inhibition of ASICs prevented RH-induced increase in the extent of post-ischemic hypoperfusion and ischemic brain injury. Since ASIC activation-induced store-operated calcium entry (SOCE) plays a role in vascular tone, next we tested if acidosis activates SOCE via activating ASICs in vascular smooth muscle cells (VSMCs). We observed that SOCE in VSMCs at lower pH is ASIC3 dependent. The results show the role of ASIC in post-ischemic hypoperfusion and increased ischemic damage in RH-exposed ITD rats. Understanding the pathways mediating exacerbated ischemic brain injury in RH-exposed ITD rats may help lower diabetic aggravation of ischemic brain damage.

Keywords: APETx2; Acidosis; Cerebral blood flow; Psalmotoxin1; Store-operated calcium entry; Vascular smooth muscle cells.

Publication types

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

MeSH terms

  • Acid Sensing Ion Channel Blockers / pharmacology
  • Acid Sensing Ion Channel Blockers / therapeutic use*
  • Acid Sensing Ion Channels / drug effects
  • Acid Sensing Ion Channels / physiology*
  • Acidosis / drug therapy*
  • Acidosis / etiology
  • Animals
  • Brain Damage, Chronic / etiology
  • Brain Damage, Chronic / prevention & control*
  • Brain Ischemia / complications*
  • Brain Ischemia / physiopathology
  • Calcium Signaling / drug effects
  • Calcium Signaling / physiology
  • Carotid Stenosis / complications*
  • Cerebrovascular Circulation
  • Cnidarian Venoms / pharmacology
  • Cnidarian Venoms / therapeutic use*
  • Diabetes Mellitus, Experimental / complications*
  • Diabetes Mellitus, Experimental / drug therapy
  • Hypoglycemia / blood
  • Hypoglycemia / chemically induced
  • Hypoglycemia / complications*
  • Hypoglycemic Agents / therapeutic use
  • Hypoglycemic Agents / toxicity*
  • Insulin / therapeutic use
  • Insulin / toxicity*
  • Laser-Doppler Flowmetry
  • Male
  • Peptides / pharmacology
  • Peptides / therapeutic use*
  • Random Allocation
  • Rats
  • Rats, Wistar
  • Recurrence
  • Spider Venoms / pharmacology
  • Spider Venoms / therapeutic use*

Substances

  • APETx2 protein, Anthopleura elegantissima
  • ASIC3 protein, rat
  • Acid Sensing Ion Channel Blockers
  • Acid Sensing Ion Channels
  • Asic1 protein, rat
  • Cnidarian Venoms
  • Hypoglycemic Agents
  • Insulin
  • PcTX1 protein, Psalmopoeus cambridgei
  • Peptides
  • Spider Venoms