Behavioral and neurochemical alterations following 5,6-dihydroxytryptamine administration into the median raphe nucleus in the cat.

The 5,6-dihydroxytryptamine administration into the median raphe nucleus in the cat resulted in an increase in the carbachol-induced emotional-defensive behavior and a decrease of 5-hydroxyindoleacetic acid and dopamine level in the hypothalamus, midbrain and amygdala. Lesions of median raphe nucleus resulted in similar, but more subtle alterations of post-carbachol emotional-defensive response similarly to dorsal raphe nucleus lesions, and they had also different biochemical effects in the "emotional regions" of the brain (hypothalamus, midbrain, amygdala). The absence of differentiated participation of both dorsal raphe nucleus and median raphe nucleus in the regulation of different aspect of the cat's behavior, and the role of both nuclei in the modulation of post-carbachol response is discussed.