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Acute and subchronic corticosterone treatment differentially modulates subcortical limbic and neostriatal nicotinic
G von Euler1, K Fuxe, U B Finnman
1Department of Histology and Neurobiology, Karolinska Institutet, Stockholm, Sweden.
Abstract:
The effects of acute and subchronic corticosterone treatment were analyzed on the competition by (-)nicotine ((-)nicotine hydrogen(+)-tartrate) on N-[3H]methylcarbamyl choline iodide ([ 3H]MCC) binding sites in membranes from the subcortical limbic forebrain and the neostriatum. Acute treatment with corticosterone (5 mg/kg, i.p., 2 h) increased the IC50 values of (-)nicotine by 230% in the subcortical limbic areas but not in the neostriatum. Subchronic corticosterone treatment (5 mg/kg, twice a day, 7 days) increased the IC50 values of (-)nicotine by 50% and slightly decreased the specific binding of [3H]MCC (5 nM) in the subcortical limbic area. In the neostriatum, subchronic treatment with corticosterone instead decreased by 50% the IC50 values of (-)nicotine and slightly increased the specific binding of [3H]MCC. The results indicate that corticosterone treatment selectively reduces the affinity of nicotinic cholinergic receptors within the subcortical limbic forebrain.