Carbachol-induced agonistic behavior in cats: aggressive or defensive response.

The effects of intrahypothalamic carbachol microinjections were investigated in unprovoked cats. The carbachol evoked mydriasis, attention, vocalization, and piloerection, i.e. features of a typical defense were usually concomitant in evoked response, while the clear-cut aggressive or escape patterns appeared only once. No basic differences were observed in the set of manifestations induced by low (1-2.5 micrograms) and high (20-40 micrograms) doses of carbachol, and from left and right hypothalamus as well as from medial and lateral portion of the hypothalamus. It is concluded that carbachol-induced response does not represent an aggressive pattern but corresponds to the cat’s defense and threat behavior.