Acute and subchronic corticosterone treatment differentially modulates subcortical limbic and neostriatal nicotinic cholinergic receptors

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 IC 5 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 IC 5) values of (−)nicotine by 50% and slightly decreased the specific binding of ([ 3H]MCC) (5 nM) subcortical limbic area. In the neostriatum, subchronic treatment with corticosterone instead decreased by 50% the IC 50 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.