title: Effects of D2 or combined D1/D2 receptor antagonism on the methamphetamine-induced one-trial and multi-trial behavioral sensitization of preweanling rats.
abstract: BACKGROUND
  There is suggestive evidence that the neural mechanisms mediating one-trial and multi-trial behavioral sensitization differ, especially when the effects of various classes of dopamine (DA) agonists are examined.
  
  
  OBJECTIVE
  The purpose of the present study was to determine the role of the D2 receptor for the induction of one-trial and multi-trial methamphetamine sensitization in preweanling rats.
  
  
  METHODS
  In a series of experiments, rats were injected with saline or raclopride (a selective D2 receptor antagonist), either alone or in combination with SCH23390 (a selective D1 receptor antagonist), 15 min prior to treatment with the indirect DA agonist methamphetamine. Acute control groups were given two injections of saline. This pretreatment regimen occurred on either postnatal days (PD) 13-16 (multi-trial) or PD 16 (one-trial). On PD 17, rats were challenged with methamphetamine and locomotor sensitization was determined.
  
  
  RESULTS
  Blockade of D2 or D1/D2 receptors reduced or prevented, respectively, the induction of multi-trial methamphetamine sensitization in young rats, while the same manipulations had minimal effects on one-trial behavioral sensitization.
  
  
  CONCLUSIONS
  DA antagonist treatment differentially affected the methamphetamine-induced sensitized responding of preweanling rats depending on whether a one-trial or multi-trial procedure was used. The basis for this effect is uncertain, but there was some evidence that repeated DA antagonist treatment caused nonspecific changes that produced a weakened sensitized response. Importantly, DA antagonist treatment did not prevent the one-trial behavioral sensitization of preweanling rats. The latter result brings into question whether DA receptor stimulation is necessary for the induction of psychostimulant-induced behavioral sensitization during early ontogeny.
authors.affiliation: Department of Psychology, 5500 University Parkway, California State University, San Bernardino, CA, 92407, USA.
authors.forename: Alena
authors.initials: A
authors.lastname: Mohd-Yusof
authors.affiliation: Department of Psychology, 5500 University Parkway, California State University, San Bernardino, CA, 92407, USA.
authors.forename: Ana
authors.initials: A
authors.lastname: Veliz
authors.affiliation: Department of Psychology, 5500 University Parkway, California State University, San Bernardino, CA, 92407, USA.
authors.forename: Krista N
authors.initials: KN
authors.lastname: Rudberg
authors.affiliation: Department of Psychology, 5500 University Parkway, California State University, San Bernardino, CA, 92407, USA.
authors.forename: Michelle J
authors.initials: MJ
authors.lastname: Stone
authors.affiliation: Department of Psychology, 5500 University Parkway, California State University, San Bernardino, CA, 92407, USA.|Present address: A.E. Gonzalez, Neurosciences Program, Stanford University School of Medicine, 1215 Welch Road Modular B, #42, Stanford, CA, 94305-5400, USA.
authors.forename: Ashley E
authors.initials: AE
authors.lastname: Gonzalez
authors.affiliation: Department of Psychology, 5500 University Parkway, California State University, San Bernardino, CA, 92407, USA. smcdouga@csusb.edu.
authors.forename: Sanders A
authors.initials: SA
authors.lastname: McDougall
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D001552:Benzazepines / Q000494:pharmacology; D000697:Central Nervous System Stimulants / Q000494:pharmacology*; D018492:Dopamine Antagonists / Q000494:pharmacology*; D065127:Dopamine D2 Receptor Antagonists / Q000494:pharmacology*; D018765:Dopamine Uptake Inhibitors / Q000494:pharmacology*; D005260:Female; D008694:Methamphetamine / Q000494:pharmacology*; D009043:Motor Activity / Q000187:drug effects; D020891:Raclopride / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D017447:Receptors, Dopamine D1 / Q000037:antagonists & inhibitors*; D017448:Receptors, Dopamine D2 / Q000187:drug effects*
chemical_list: D001552:Benzazepines; D000697:Central Nervous System Stimulants; D018492:Dopamine Antagonists; D065127:Dopamine D2 Receptor Antagonists; D018765:Dopamine Uptake Inhibitors; D017447:Receptors, Dopamine D1; D017448:Receptors, Dopamine D2; C534628:SCH 23390; D020891:Raclopride; D008694:Methamphetamine
keywords: Behavioral sensitization; Methamphetamine; Ontogeny; Raclopride; SCH23390