Photomicrographs of immunohistochemistry showing c-Fos expression in the medial preoptic area. Note that in comparison to the vehicle treatment, only DOI, but not quinpirole, HAL or CLZ, produced a significant increase in c-Fos expression in the MPOA (B,C,D,G). DOI pretreatment significantly increased c-Fos expression, while quinpirole had little effect in both HAL- and CLZ-treated rats (E,F,H,I). Scale bar = 100 μm.