AI Article Synopsis
- Behavioral sensitization to amphetamine leads to increased locomotor activity with repeated doses, due to changes in brain neurotransmitter pathways.
- In a study, rats received either amphetamine or saline and were tested for locomotor activity 48 hours later, revealing that sensitized rats had notable increases in activity compared to controls.
- The research found enhanced Fos-IR (a marker of neuronal activation) mainly in specific brain regions, indicating that different areas of the brain may specialize in the effects of amphetamine sensitization.
Article Abstract
Behavioral sensitization to the locomotor activating effects of amphetamine refers to the progressive, long lasting increase in locomotor activity that occurs with repeated injections. This phenomenon is thought to result from neuroadaptations occurring in the projection fields of mesocorticolimbic dopaminergic neurons. In the present study, we investigated the effects of amphetamine sensitization on Fos immunoreactivity (Fos-IR) in subterritories of the nucleus accumbens (core and shell) and medial prefrontal cortex (mPFC; dorsal and ventral) using stereology. Rats received five daily injections of amphetamine (1.5 mg/kg, i.p.) or saline. Behavioral sensitization was measured 48 h following the last injection, in response to a challenge injection of 1.5 mg/kg amphetamine. Sensitized rats showed a greater enhancement of locomotor activity upon drug challenge compared with their saline counterparts. Densities of Fos-positive nuclei were enhanced more in the dorsal than the ventral mPFC subterritory, whereas in the nucleus accumbens, densities of Fos-positive nuclei were increased more in the core than the shell of amphetamine-sensitized rats compared to controls. These results represent, to our knowledge, the first published report using stereological methods to quantify Fos-IR in the brain and suggest functional specialization of cortical and limbic regions in the expression of behavioral sensitization to amphetamine.
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| http://dx.doi.org/10.1016/s0006-8993(02)03034-2 | DOI Listing |
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