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Brain Res. 1994 Feb 28;638(1-2):311-24.

The effect of chronic imipramine administration on the densities of 5-HT1A and 5-HT2 receptors and the abundances of 5-HT receptor and transporter mRNA in the cortex, hippocampus and dorsal raphe of three strains of rat.

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Unit on Neuroendocrine Immunology and Behavior, National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892.


We have recently demonstrated that the LEW/N rat contains lower concentrations of cortical and hippocampal 5-HT1A receptors compared with the F344/N and out-bred HSD rats. To further characterize these strains, we investigated the effect of chronic (8 wk) imipramine administration (5 mg/kg/day) on 5-HT1A and 5-HT2 receptor densities and mRNA in the cortex and hippocampus and 5-HT transporter mRNA in the dorsal raphe of LEW/N, HSD, and F344/N rats, using quantitative autoradiography and in situ hybridization histochemistry. After imipramine treatment, a significant increase in the levels of hippocampal 5-HT1A receptors, but not mRNA, was observed in LEW/N rats while the abundance of hippocampal 5-HT1A receptor mRNA, but not 5-HT1A receptor densities, decreased in F344/N rats. Cortical and hippocampal 5-HT2 receptor densities, but not mRNA, significantly decreased after imipramine administration in all three strains. Finally, 5-HT1A receptor densities and the abundance of mRNAs encoding the 5-HT1A receptor and 5-HT transporter in the dorsal raphe remained unaltered after imipramine administration in all three strains. The effects of imipramine on the levels of cortical and hippocampal 5-HT1A and 5-HT2 receptors and their transcripts, therefore, appear to be strain-dependent. The implications of these findings are discussed.

[Indexed for MEDLINE]

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