Fig. 2.

Effects of P2 and glutamate receptors blockade in the NTS on cardiovascular responses elicited by stimulation of the HDA. a Representative recording of one animal in response to stimulation of the hypothalamic defense area (HDA; 150–200 μA, 0.6 ms, 100 Hz for 5 s) before and after bilateral microinjections of suramin (10 mM) and kynurenate (50 mM) in the nucleus tractus solitarii (NTS). AP arterial blood pressure; HR heart rate; HVC hindlimb vascular conductance. b Group data showing the maximum response generated by hypothalamic stimulation after antagonism of P2 (sur NTS), glutamate (kyn NTS) and both (sur + kyn) receptors in the NTS. c Pooled HVC responses elicited by stimulation of the HDA during control, after blockade of P2 receptors, glutamate receptors, and combined P2 and glutamate receptors in the NTS. Black squares, averaged curve during control; dark graycircles, averaged curve after blockade; in light gray, standard error of the mean. d Grouped data of increases elicited in mean arterial pressure (MAP) and HR by hypothalamic stimulation before and after after antagonism of P2 (sur NTS), glutamate (kyn NTS), and both (sur + kyn) receptors in the NTS. e Photomicrograph of a coronal section showing electrolytic lesion of the hypothalamic defense area, corresponding to the perifornical hypothalamus (PeF). mt mammillothalamic tract; f fornix; DMH dorsomedial hypothalamus; VMH ventromedial hypothalamus. ***P < 0.001 difference to control; n.s., P > 0.05