Abstract: C-Fos immunohistochemistry was used to define rat brain regions activated during expression of a CTA which was established by intake of saccharin solution (CS) paired with i.p. injection of CY or LiC1. Re-exposure to saccharin induced dense c-Fos-like immunoreactivity (c-FLI) in hypothalamus, amygdala and limbic cortex et al. in both CY-paired and LiC1-paired groups, but this pattern of activation was not evident in saccharin controls or CY (LiC1)-unpaired groups. However there were several brain regions which showed some difference in c-FLI between CY-paired and LiC1-paired groups. CY-paired CS induced denser c-FLI than LiC1-paired CS in anterodorsal thalamic nucleus (AD), cingulate cortex (Cg), lateral hypothalamic area(LH), subfornical organ (SFD) and supraoptic nucleus(SO), retrosplenial granular cortex (RSG), these regions may be related to the action of immunosuppression induced by CY; But in accumbens nucleus (Acb), basotateral amydaloid nucleus(BL), ventral part of Latelal septal nucleus (LSV), LiC1-paired CS induced denser c-FLI than CY-paired CS, these regions may be related to the pharmacologic effects of LiC1 to the brain.

Key words: conditioned taste aversion, c-Fos, Cyclophosphamide, LiC1