Absence of sympathetic cholinergic vasodilatation in cats during early stages of affective behaviour elicited by stimulation of central amygdala, postero-lateral hypothalamus and locus coeruleus.

1. Stimulation of the central amygdala, postero-lateral hypothalamus and locus coeruleus in cats resulted in a sustained increase in arterial pressure, an increase in heart rate, with a poststimulation bradycardia and an increase in peripheral resistance (vasoconstriction in the vessels of the hindlimbs). The behavioural pattern was characterized by an alerting reaction. Increased stimulus intensities resulted in rage reactions if the amygdala or the hypothalamus were stimulated. 2. Stimulation of the basal amygdala resulted in a cardiovascular pattern characterized by a sympathetic cholinergic vasodilatation. The concomitantly observed behaviour was characterized by alerting, anxious behaviour, eventually resulting in defence. 3. Alerting was not necessarily linked to sympathetic cholinergic vasodilatation. 4. The cardiovascular pattern including sustained vasoconstriction of the vessels of the hindlimbs was supposed to be of greater importance for the induction of hypertension than the cardiovascular pattern, including sympathetic cholinergic vasodilatation.