c-fos antisense attenuates Fos expression in rat central neurons induced by hemorrhage

Hemorrhage caused by withdrawing 3-4 cm3 of blood from adult rats over a period of 1-2 h induced the expression of Fos proteins, which were detected by immunocytochemical methods in neurons of the hypothalamic supraoptic (SON) and paraventricular (PVN) nuclei, area postrema, nucleus of the solitary tract (NTS), ventrolateral medulla (VLM) and in intermediolateral cell column (IML) of the spinal cord. Daily intraventricular (i.c.v.) injections of c-fos antisense (50 nmol 5 microliters -1) for 2 days prior to hemorrhage markedly attenuated the extent and intensity of Fos-immunoreactivity (FOS-IR) compared with that of rats injected with c-fos sense in the areas mentioned above. The results indicate the effectiveness of i.c.v. administration of c-fos antisense in blocking Fos expression in central neurons following hemorrhage.