GABA concentrations in the striatum following repetitive cerebral ischemia

Abstract

GABAergic neurons in the striatum are very sensitive to the effects of ischemia. The progressive decline in striatal GABA following transient forebrain ischemia in gerbils may be secondary to either a decreased production or an increase in reuptake mechanisms or both. The current experiment was designed to evaluate release of GABA by stimulation with K+ or inhibition of its uptake with nipecotic acid or their combination (K+ nipecotic) after repetitive forebrain ischemia in gerbils by in-vivo microdialysis on Days 1, 3, 5, and 14 following the insult. Infusion of nipecotic acid or potassium chloride, resulted in a significant increase in extracellular GABA. This response was significantly decreased in the post-ischemic animals. The synergistic effect of increased GABA concentrations by the infusion of nipecotic acid + potassium chloride seem in the controls was not evident in the post-ischemic animals. In conclusion, though there is a reduction in the extracellular GABA concentrations in the first week following an ischemic insult, restorative mechanisms are operative in the second week as seen by the increasing GABA concentrations.

Studies on the Protective Effects of Scutellarein against Neuronal Injury by Ischemia through the Analysis of Endogenous Amino Acids and Ca2+Concentration Together with Ca2+-ATPase Activity

“…Ca 2+ -ATPase, which was an important modulator of the intracellular calcium level, could pump Ca 2+ back into the endoplasmic Journal of Chemistry Figure 2: The possible mechanism of excitotoxicity during ischemia/reperfusion. reticulum against a steep concentration gradient [31]. However, endoplasmic reticulum (ER) calcium homeostasis was disturbed during ischemia, because ATP was needed to fuel the ER Ca 2+ -ATPase [32].…”

Cortical brain microdialysis and temperature monitoring during hypothermic circulatory arrest in humans

“…Glutamate in the perfusate was analysed by high performance liquid chromatography (HPLC). We employed electrochemical detection using a modification of the method originating with Donazanti and Yamamoto23 as was previously described in detail 2425 Precolumn derivatisation of amino acids with orthophthaldialdehyde (OPA/betamercaptoethanol ) was performed before electrochemical detection with a 715 Ultra Wisp sample processor ( (Nopak C18; 3.9×150 mm; Waters, Toronto, Canada).…”

Phenelzine: An Old Drug That May Hold Clues to The Development of New Neuroprotective Agents

“…Initial concomitant increases in brain levels of glutamate and GABA in cerebral ischemia have been reported. However, the increase in GABA is usually much more transient than that of glutamate, with the initial increase in brain GABA followed by a longer-lasting decrease in brain levels and function of this inhibitory neurotransmitter (38)(39)(40)(41)(42)(43)(44)(45). This decrease in GABAergic activity likely exacerbates the neuronal damage induced by excitotoxicity in the long term, since the opposing actions of the GABAergic system on the hyperactive glutamatergic system are reduced (42).…”