REGION-SPECIFIC EFFECTS OF CHRONIC LITHIUM ADMINISTRATION ON NEUROPEPTIDE-Y AND SOMATOSTATIN MESSENGER-RNA EXPRESSION IN THE RAT-BRAIN

The aim of this study was to examine the effects of 4-week lithium (Li +) food supplementation on neuropeptide mRNA expression in the rat bra in. In situ hybridisation was used to determine the effects on the exp ression of neuropeptide Y (NPY) and somatostatin (SS) mRNA. Increases in NPY mRNA levels were seen in the hippocampus, layers II-III of the entorhinal cortex, nucleus accumbens shell and in the medial caudate-p utamen. Increases in SS mRNB expression were seen in the layers IV-VI of the entorhinal cortex and in the lateral caudate putamen. Thus, Li appears to affect discrete populations of NPY and SS mRNA expressing neurons, with possible relevance to beneficial effects of Li+ in affec tive disorders.