title: DCPIB, the proposed selective blocker of volume-regulated anion channels, inhibits several glutamate transport pathways in glial cells.
abstract: 4-(2-Butyl-6,7-dichloro-2-cyclopentyl-indan-1-on-5-yl) oxobutyric acid (DCPIB) was identified as the selective blocker of volume-regulated anion channels (VRAC). VRAC are permeable to small inorganic and organic anions, including the excitatory neurotransmitter glutamate. In recent years DCPIB has been increasingly used for probing the physiologic and pathologic roles of VRAC and was found to potently suppress pathologic glutamate release in cerebral ischemia. Because ischemic glutamate release can be mediated by a plethora of mechanisms, in this study we explored the selectivity of DCPIB toward the majority of previously identified glutamate transporters and permeability pathways. l-[(3)H]glutamate, d-[(3)H]aspartate, and l-[(14)C]cystine were used to trace amino acid release and uptake. We found that in addition to its well-characterized effect on VRAC, DCPIB potently inhibited glutamate release via connexin hemichannels and glutamate uptake via the glutamate transporter GLT-1 in rat glial cells. In contrast, DCPIB had no direct effect on vesicular glutamate release from rat brain synaptosomes or the cystine/glutamate exchange in astrocytes. The compound did not affect the astrocytic glutamate transporter GLAST, nor did it block glutamate release via the P2X(7)/pannexin permeability pathway. The ability of DCPIB to directly block connexin hemichannels was confirmed using a gene-specific siRNA knockdown approach. Overall, our data demonstrate that DCPIB influences several glutamate transport pathways and that its effects on VRAC in vivo should be verified using additional pharmacological controls.
authors.affiliation: Center for Neuropharmacology and Neuroscience, Albany Medical College, 47 New Scotland Avenue, Albany, NY 12208, USA.
authors.forename: Nicole H
authors.initials: NH
authors.lastname: Bowens
authors.forename: Preeti
authors.initials: P
authors.lastname: Dohare
authors.forename: Yu-Hung
authors.initials: YH
authors.lastname: Kuo
authors.forename: Alexander A
authors.initials: AA
authors.lastname: Mongin
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology; D027182:Amino Acid Transport System y+ / Q000037:antagonists & inhibitors / Q000502:physiology; D026905:Amino Acid Transport Systems / Q000037:antagonists & inhibitors / Q000502:physiology*; D026922:Amino Acid Transport Systems, Acidic; D000818:Animals; D001253:Astrocytes / Q000187:drug effects* / Q000378:metabolism; D001692:Biological Transport; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology; D017630:Connexins / Q000037:antagonists & inhibitors / Q000502:physiology; D003517:Cyclopentanes / Q000494:pharmacology*; D027341:Excitatory Amino Acid Transporter 1 / Q000037:antagonists & inhibitors / Q000502:physiology; D027342:Excitatory Amino Acid Transporter 2 / Q000037:antagonists & inhibitors / Q000502:physiology; D018698:Glutamic Acid / Q000378:metabolism*; D007189:Indans / Q000494:pharmacology*; D017628:Microglia / Q000187:drug effects* / Q000378:metabolism; D010539:Permeability; D061251:Primary Cell Culture; D051381:Rats; D058486:Receptors, Purinergic P2X7 / Q000502:physiology; D013574:Synaptosomes / Q000378:metabolism
chemical_list: D000255:Adenosine Triphosphate; D027182:Amino Acid Transport System y+; D026905:Amino Acid Transport Systems; D026922:Amino Acid Transport Systems, Acidic; D017630:Connexins; D003517:Cyclopentanes; D027341:Excitatory Amino Acid Transporter 1; D027342:Excitatory Amino Acid Transporter 2; D018698:Glutamic Acid; D007189:Indans; D058486:Receptors, Purinergic P2X7; C443139:4-(2-butyl-6,7-dichlor-2-cyclopentyl-indan-1-one-5-yl)oxybutyric acid; C000723960:Slc7a11 protein, rat