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Potentiation of amphetamine‐mediated responses in caffeine‐sensitized rats involves modifications in A 2A receptors and zif‐268 mRNAs in striatal neurons
Author(s) -
Tronci Elisabetta,
Simola Nicola,
Carta Anna R.,
De Luca M. Antonietta,
Morelli Micaela
Publication year - 2006
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.2006.03943.x
Subject(s) - amphetamine , long term potentiation , caffeine , neuroscience , receptor , pharmacology , chemistry , biology , endocrinology , medicine , dopamine
Subchronic intermittent administration of caffeine induces sensitization of motor behaviour and promotes cross‐sensitization to amphetamine motor activity. In order to evaluate the possible mechanisms at the basis of these effects, modifications in A 2A receptor and zif‐268 mRNAs were evaluated in rats subchronically treated with caffeine (15 mg/kg i.p.) and challenged with caffeine (15 mg/kg i.p.) or amphetamine (0.5, 1 mg/kg s.c.) 3 days after discontinuation of treatment. Results showed that the sensitized motor response to caffeine was associated with a decrease of adenosine A 2A receptor and zif‐268 mRNA levels in the striatum and nucleus accumbens, whereas cross‐sensitization to amphetamine was linked to a more pronounced increase of zif‐268 mRNA levels in the striatum, but not in the nucleus accumbens. Single‐cell analysis showed that zif‐268 mRNA modifications occurred in Enk(+) striatopallidal neurons after acute or subchronic treatment with caffeine and in Enk(–) striatonigral neurons after acute amphetamine administration. Potentiation of amphetamine effects was not associated with modifications of amphetamine‐induced dopamine release in nucleus accumbens in caffeine‐pretreated rats compared with vehicle‐pretreated rats. Results demonstrate that sensitization to caffeine and cross‐sensitization to amphetamine are associated with post‐synaptic neuroadaptive changes in selective neuronal populations of the striatum.