, Volume 190, Issue 1, pp 65-72
Date: 18 Oct 2006

Nucleus accumbens PKA inhibition blocks acquisition but enhances expression of amphetamine-produced conditioned activity in rats

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Abstract

Rationale

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.

Objectives

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

Materials and methods

After 5 days of habituation, a test environment was paired with bilateral NAc injections of amph (0.0 or 25.0 μg) and the PKA inhibitor Rp-cAMPS (0.0, 5.0, 10.0, or 20.0 μg) 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 μg 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.