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- Title
Activation of 5-HT[sub 1B] receptors in the nucleus accumbens reduces amphetamine-induced enhancement of responding for conditioned reward.
- Authors
Fletcher, Paul J.; Korth, Karin M.
- Abstract
Abstract Previously, we have demonstrated that 5-hydroxytryptamine (5-HT) injected into the nucleus accumbens attenuates the potentiating effects of d-amphetamine on responding for conditioned reward (CR). The present studies examined the 5-HT receptor involved in this effect by investigating the effects of 5-HT agonists with differing affinities for 5-HT[sub 1] and 5-HT[sub 2] receptors on d-amphetamine-induced potentiation of responding for CR. Rats were trained to associate a light/tone stimulus (subsequently the CR) with water delivery. In a test phase, they were allowed access to a lever delivering the CR, and an inactive (NCR) lever. Responding on the CR lever was greater than responding on the NCR lever, indicating that the light/tone stimulus functioned as a CR. Responding for the CR was selectively potentiated by injections of d-amphetamine (10 micro g) into the nucleus accumbens. This effect was reduced by injections into the nucleus accumbens of 5-CT (0.5 and 1 micro g), RU24969 (10 micro g), CP93,129 (1.25 and 2.5 micro g) but not by DOI (10 micro g) or 8-OH-DPAT (5 micro g). The lower doses of 5-CT and CP93,129 did not reduce baseline responding for CR, or responding for water in a separate group of animals, indicating that the effects of these drugs were behaviourally selective. The higher doses abolished the CR effect, and in the case of 5-CT and RU24969 also reduced responding for water. All of the effective drugs share in common the ability to stimulate 5-HT[sub 1B] receptors, albeit with differing selectivities. The effect of CP93,129, the most selective of the 5-HT[sub 1B] agonists, to inhibit the response-potentiating effect of d-amphetamine was reversed by the5-HT[sub 1B/1D] antagonist GR127935 (3 mg/kg). The results indicate that activation of 5-HT[sub 1B] receptors within the nucleus accumbens attenuates the effects of a...
- Subjects
SEROTONIN; NUCLEUS accumbens; AMPHETAMINES; DOPAMINE
- Publication
Psychopharmacology, 1999, Vol 142, Issue 2, p165
- ISSN
0033-3158
- Publication type
Article
- DOI
10.1007/s002130050876