title: Effects of chronic inhibition of GABA synthesis on attention and impulse control.
abstract: BACKGROUND
  Cortical GABA regulates a number of cognitive functions including attention and working memory and is dysregulated in a number of psychiatric conditions. In schizophrenia for example, changes in GABA neurons [reduced expression of glutamic acid decarboxylase (GAD), parvalbumin (PV) and the GABA reuptake transporter (GAT1)] suggest reduced cortical GABA synthesis and release; these changes are hypothesized to cause the cognitive deficits observed in this disorder. The goals of this experiment were to determine whether chronically reducing GAD function within the rat PFC causes attention deficits and alterations in PV and GAT1 expression.
  
  
  METHODS
  Male Sprague Dawley rats were trained on the 5-choice serial reaction time task (5CSRTT, a task of attention) until they reached criterion performance and then were implanted with a bilateral cannula aimed at the medial PFC. Cannulae were connected to osmotic minipumps that infused the GAD inhibitor l-allylglycine (LAG, 3.2μg/0.5μl/h) for 13days. Following a 5-day recovery from surgery rats were tested on the standard 5CSRTT for 5 consecutive days and then tested on two modifications of the 5CSRTT. Finally, locomotor activity was assessed and the rats sacrificed. Brains were rapidly extracted and flash frozen and analyzed for the expression of GAD67, PV, GAT1 and the obligatory NMDA receptor subunit NR1.
  
  
  RESULTS
  Chronic LAG infusions transiently impaired attention, persistently impaired impulse control and increased locomotor activity. Behavioral changes were associated with an upregulation of GAD67, but no change in PV, GAT1 or NR1 expression.
  
  
  CONCLUSIONS
  Chronic inhibition of GABA synthesis within the medial PFC, increased impulsive behavior and locomotion, but did not impair attention; results consistent with previous research following acute inhibition of GABA synthesis. Moreover, our data do not support the hypothesis that decreasing GABA synthesis and release is sufficient to cause changes in other GABA-related proteins.
authors.affiliation: Department of Neuroscience, Oberlin College, Oberlin OH, 44074, USA. Electronic address: tpaine@oberlin.edu.
authors.forename: Tracie A
authors.initials: TA
authors.lastname: Paine
authors.affiliation: Department of Neuroscience, Oberlin College, Oberlin OH, 44074, USA.
authors.forename: Elizabeth K
authors.initials: EK
authors.lastname: Cooke
authors.affiliation: Department of Neuroscience, Oberlin College, Oberlin OH, 44074, USA.
authors.forename: Daniel C
authors.initials: DC
authors.lastname: Lowes
mesh_terms: D000818:Animals; D001288:Attention / Q000187:drug effects*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D018756:GABA Antagonists / Q000494:pharmacology* / Q000627:therapeutic use; D050485:GABA Plasma Membrane Transport Proteins / Q000096:biosynthesis; D005968:Glutamate Decarboxylase / Q000037:antagonists & inhibitors / Q000378:metabolism; D007175:Impulsive Behavior; D008297:Male; D010320:Parvalbumins / Q000378:metabolism; D017397:Prefrontal Cortex / Q000187:drug effects / Q000201:enzymology; D051381:Rats; D017207:Rats, Sprague-Dawley; D011930:Reaction Time / Q000187:drug effects; D016194:Receptors, N-Methyl-D-Aspartate / Q000096:biosynthesis / Q000235:genetics; D005680:gamma-Aminobutyric Acid / Q000096:biosynthesis*
chemical_list: D004791:Enzyme Inhibitors; D018756:GABA Antagonists; D050485:GABA Plasma Membrane Transport Proteins; C409466:NR1 NMDA receptor; D010320:Parvalbumins; D016194:Receptors, N-Methyl-D-Aspartate; D005680:gamma-Aminobutyric Acid; D005968:Glutamate Decarboxylase
keywords: Attention; GABA; GAD67; Impulsive; Schizophrenia; l-Allylglycine