Selective dopamine D4 receptor agonist (A-412997) improves cognitive performance and stimulates motor activity without influencing reward-related behaviour in rat

Behav Pharmacol. 2008 Dec;19(8):765-76. doi: 10.1097/FBP.0b013e32831c3b06.

Abstract

Current therapies for attention deficit hyperactivity disorder comprise psychostimulants, which block the dopamine transporter and/or stimulate the release of dopamine, leading to a global elevation in extrasynaptic dopamine. These drugs are, however, associated with a series of unwanted side effects such as insomnia, anorexia, headache, stomach problems and potential drug abuse. Recent evidence suggests that the dopamine D4 receptor may represent a selective dopamine target that could mediate cognitive as well as striatal motor processes. In this study we compare the effects of a selective D4 receptor agonist, A-412997, with methylphenidate or amphetamine in preclinical models of efficacy versus abuse liability. Both methylphenidate and A-412997 improved a temporally induced deficit in the rat novel object recognition task at doses 10-fold lower than those stimulating activity. In both cases, procognitive doses were associated with elevated extracellular levels of dopamine and acetylcholine in the medial prefrontal cortex. In contrast to amphetamine, A-412997 did not mediate reward-related behaviour in the conditioned place preference paradigm, a preclinical rodent test used to assess potential abuse liability. Collectively, these data suggest that selective activation of the D4 receptor may represent a target for the treatment of attention deficit hyperactivity disorder without the potential drug abuse liability associated with current psychostimulant therapies.

MeSH terms

  • Acetamides / pharmacology*
  • Acetylcholine / metabolism
  • Amphetamine / pharmacology
  • Animals
  • Behavior, Animal / drug effects
  • Cognition / drug effects*
  • Disease Models, Animal
  • Dopamine / metabolism
  • Dopamine Agonists / pharmacology*
  • Dose-Response Relationship, Drug
  • Drug Administration Routes
  • Extracellular Fluid / drug effects
  • Male
  • Memory Disorders / drug therapy
  • Methylphenidate / pharmacology
  • Microdialysis / methods
  • Motor Activity / drug effects*
  • Pattern Recognition, Visual / drug effects
  • Photic Stimulation
  • Pyridines / pharmacology*
  • Rats
  • Rats, Sprague-Dawley
  • Receptors, Dopamine D4 / agonists*
  • Reward*

Substances

  • 2-(3',4',5',6'-tetrahydro-2'H-(2,4') bipyridinyl-1'-yl)-N-m-tolyl-acetamide
  • Acetamides
  • Dopamine Agonists
  • Pyridines
  • Receptors, Dopamine D4
  • Methylphenidate
  • Amphetamine
  • Acetylcholine
  • Dopamine