Expression of early genes in the rat brain after administration of corticoliberin into the neostriatum

In situ hybridization using oligonucleotide probes was used to study the effects of intrastriatal microinjection of corticoliberin on the expression of the early genes c-fos, jun B, c-jun, and NGFIA in the rat brain. Administration of corticoliberin (0.25 g) into the neostriatum induced the expression of mRNA encoded by the early genes c-fos, jun B, and NGFIA in both the neostriatum itself and in its efferent structures, particularly the nucleus accumbens and various parts of the cortex. Intrastriatal microinjection of corticoliberin had no effect on the expression of mRNA for the oncogene c-jun in the brain. These results suggest that neuronal activation in the neostriatum and its projection targets manifest as the expression of early genes is one of the mechanisms underlying the adaptive effects of corticoliberin in stress.