Nucleus accumbens PKA inhibition blocks acquisition but enhances expression of amphetamine-produced conditioned activity in rats.
BACKGROUND
The nucleus accumbens (NAc) plays a central role in dopamine-produced reward-related learning. In previous studies, the cyclic adenosine monophosphate-dependent protein kinase (PKA) inhibitor Rp-Cyclic 3',5'-hydrogen phosphorothioate adenosine triethylammonium salt (Rp-cAMPS) blocked the acquisition but not expression of NAc reward-related learning for natural rewards and the acquisition of psychostimulant drug conditioning.


OBJECTIVE
The current study assessed the role of PKA in the expression of NAc amphetamine (amph)-produced conditioning using conditioned activity (CA).


METHODS
After 5 days of habituation, a test environment was paired with bilateral NAc injections of amph (0.0 or 25.0 micro g) and the PKA inhibitor Rp-cAMPS (0.0, 5.0, 10.0, or 20.0 micro g) over three 60-min conditioning sessions separated by 48 h. To test for effects on expression, some groups received vehicle or amph alone before conditioning sessions and were injected with 0.0, 0.25, 5.0, or 20.0 mug of Rp-cAMPS before the single 60-min test session.


RESULTS
Amph produced acute increases in locomotion and robust CA. Rp-cAMPS impaired the acquisition of amph-produced CA but not its expression; in fact, it enhanced expression.


CONCLUSIONS
Results show that PKA inhibition blocks the acquisition but not the expression of amph-produced conditioning.
Gerdjikov
Todor V
TV
Department of Psychology, Queen's University, Kingston, ON, Canada.
Giles
Andrew C
AC
Swain
Shelley N
SN
Beninger
Richard J
RJ
D000661:Amphetamine / Q000494:pharmacology*; D000818:Animals; D001245:Association Learning / Q000187:drug effects / Q000502:physiology; D001931:Brain Mapping; D000697:Central Nervous System Stimulants / Q000494:pharmacology*; D003216:Conditioning, Operant / Q000187:drug effects*; D000242:Cyclic AMP / Q000031:analogs & derivatives* / Q000494:pharmacology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors*; D004292:Dominance, Cerebral / Q000187:drug effects / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D008297:Male; D011939:Mental Recall / Q000187:drug effects* / Q000502:physiology; D009042:Motivation; D009043:Motor Activity / Q000187:drug effects* / Q000502:physiology; D009714:Nucleus Accumbens / Q000187:drug effects* / Q000502:physiology; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D013873:Thionucleotides / Q000494:pharmacology*
D000697:Central Nervous System Stimulants; D047428:Protein Kinase Inhibitors; D013873:Thionucleotides; C016957:adenosine-3',5'-cyclic phosphorothioate; D000661:Amphetamine; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases