The rostral part of the nucleus tractus solitarius (NTS) is well known as first order gustatory relay center. However, neurons in the rostral NTS also receive afferent inputs from a lot of different structures and respond to various kinds of peripheral stimuli. For example, somatosensory fibers from oral cavity and baroreceptor afferent fibers have shown to project to the rostral NTS. Therefore, we examined the effects of the aortic depressor nerve (AND) and lingual-trigeminal nerve (LTN) stimulations on the activity of the rostral NTS neurons, and also investigated whether these neurons exhibit a pulse-related activity. The experiments were carried out on 7 male SD rats (300-400 g) under urethane-chloralose anesthesia (500 mg/kg and 50 mg/kg, respectively, i.p.). The arterial blood pressure and an ECG were recorded. The right ADN and LTN were dissected and prepared for stimulation. Animals were artificially ventilated with room air containing 20-35% O2 following neuromuscular blockade with pancronium bromide (1 mg/kg, i.v.). The depth of anesthesia was assessed by monitoring the stability of the arterial pressure and heart rate to noxious pinching of the hind paw at regular intervals and if necessary anesthesia was supplemented by injections of urethane-chloralose (50 and 5 mg/kg/h; i.v.). Single unit activity of the rostral NTS neurons were extracellularly recorded using a single microelectrode, and test stimuli (0.1-0.3mA, 1 pulse with 0.2 ms duration at 10Hz for 10 seconds) were applied to the AND and LTN. In the ECG/ABP-triggered correlation histogram, a neuron was classified as having a pulse-related activity if the cardiac coefficient exceeds 2.0. All data are presented as mean ± S.D., and compared using Student’s t test. The recording sites were marked and histologically verified. A total of 36 rostral NTS neurons with spontaneous activity were recorded. Among them, 28 neurons (78%) exhibited a pulse-related activity, whereas 8 neurons (22%) did not exhibit it. The ADN stimulation significantly altered (p<0.05) their firing rates in 12 (33%) neurons, and did not (p>0.05) in 24 (67%) neurons. Out of 12, 11 neurons decreased their firing rate (3.6± 3.5 spikes/sec vs 8.1± 6.1 spikes/sec for pre-stimuli; p<0.05), and 1 neuron increased their firing rate (4.7 spikes/sec vs 2.2 spikes/sec for pre-stimuli; p<0.05). On the other hand, the LTN stimulation significantly altered (p<0.05) their firing rates in 17 (47%) neurons, and did not (p>0.05) in 19 (53%) neurons. Out of 17, 11 neurons decreased their firing rate (4.8± 3.6 spikes/sec vs 10.9 ± 6.9 spikes/sec for pre-stimuli; p<0.05), and 6 neurons increased their firing rate (11.1 ± 7.1 spikes/sec vs 5.0 ± 3.6 spikes/sec for pre-stimulus, p<0.05). We conclude that ADN and LTN stimulations exert inhibitory/excitatory effects on less than half of the rostral NTS neurons, and these neuronal activities may be involved in the reflex cardiovascular responses in part.