Average changes in the DIA burst frequency (Panel A) and amplitude (panel B), mean arterial pressure (MAP, panel C), heart rate (HR, panel D) and mean abdominal muscle activity (ABD, panel E) induced by AIH before (5–25 min) and after (35–60 min) bilateral microinjections of muscimol in the RTN/pFRG of anesthetized animals with vagus nerve intact. The microinjections were performed thirty minutes after the AIH (arrows). * - P <0.05 - different from respective baseline values. Panel F: schematic drawing of the ventral surface of the medulla, combined with a photomicrography of coronal section of the brainstem of a rat, representative of the group, illustrating sites of injection in the RTN/pFRG. Abbreviations: RPa, raphe pallidus nucleus, 7, facial nucleus, sp5, spinal trigeminal nucleus, py, pyramidal tract.