We previously showed that 5-HT₂ receptor activation in the nucleus of the tractus solitarius (NTS) produced hypotension, bradycardia and facilitation of the baroreflex bradycardia. Activation of the preoptic area (POA) of the hypothalamus, which is involved in shock-like passive behaviours, induces similar modifications. Previous studies showed that blockade of the infralimbic (IL) part of the medial prefrontal cortex, which sends projections to POA, produced an inhibitory influence on the baroreflex cardiac response. Thus, to assess the possible implication of NTS 5-HT₂ receptors in passive cardiovascular responses, we analyzed in anaesthetized rats the effects of NTS inhibition and NTS 5-HT₂ receptor blockade, on the cardiovascular modifications induced by chemical (D, L-homocysteic acid) and electrical (50 Hz, 150-200 µA) stimulation of IL or POA. Intra-NTS microinjections of muscimol, a GABA_A receptor agonist, prevented the decreases in blood pressure and heart rate normally evoked by IL or POA activation. In addition, we found that intra-NTS microinjection of [R(+)-alpha-(2,3-dimethoxyphenyl)-1-[2-(4-fluorophenylethyl)]-4-piperidine-methanol] (MDL-100907), a specific 5-HT_2A receptor antagonist, did not affect the decreases in cardiovascular baseline parameters induced by IL or POA stimulation, but prevented the facilitation of the aortic baroreflex bradycardia normally observed during IL (+65 % and +60 %) or POA (+70 % and +69 %) electrical and chemical stimulation, respectively. These results show that NTS 5-HT_2A receptors play a key role in the enhancement of the cardiac response of the baroreflex but not in the changes in basal heart rate and blood pressure, induced by IL or POA stimulation.