Area postrema: Gastric vagal input from proximal stomach and interactions with nucleus tractus solitarius in cat

The responses of neurons in the area postrema (AP) during electrical stimulation of the gastric vagal branches that serve the proximal stomach were evaluated in halothane-anesthetized cats. The evoked orthodromic responses were localized bilaterally in the AP and had a mean latency of 272 ms (SD ± 53.1). Convergence of gastric vagal input on single AP units from afferents in the ventral and dorsal vagal trunks serving the proximal stomach was observed on 13% of gastric vagally evoked neurons. Reciprocal connections between neuronal populations in the nucleus tractus solitarius and the AP were identified electrophysiologically by direct microstimulation of the former structure. Spontaneously AP discharging units showed an increase in frequency after NTS microstimulation. Our study provided evidence that the AP neurons received vagal input from the proximal stomach and suggested a potential role of the AP in the regulation of food intake.