Chronic nicotine and smoking exposure decreases GABAB1 receptor expression in the rat hippocampus

Nicotine and smoking have long been proved to play an important role in cognition and memory in the hippocampus. This effect is closely related to the gamma-aminobutyric acid (GABA)ergic system. Previous research has focused on functional and pharmacological aspects of nicotine's modulation activity. In this study, the effects of nicotine and different doses of smoking on GABA(B1) expression in the rat hippocampus have been examined using in situ hybridization and RNase protection assay. GABA(B1) receptor mRNAs were intensely expressed in the CA1, CA2, CA3, and dentate gyrus areas of the hippocampus. Nicotine and smoking doses dependently decreased GABA(B1) receptor expression in the hippocampus. These results revealed new aspects of nicotine's modulation on GABA(B) receptor, and on learning and memory. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved.