Characterization and regulation of tachykinin receptors in the nucleus tractus solitarius

Abstract

1. The characteristics, localization and regulation of tachykinin receptors in the rat nucleus tractus solitarius (NTS) involved in respiratory control were investigated using a combination of in vivo microinjection and in vitro autoradiographic techniques. 2. Microinjection of receptor-selective tachykinin agonists and antagonists into the NTS of urethane-anaesthetized rats suggests that stimulation of NK1 and NK3 receptors increases tidal volume, whereas NK2 and NK3 receptor activation produces a bradypnoea. 3. Depletion of NK1 receptors in the NTS due to either ageing or acute hypoxia correlates with a markedly reduced respiratory response to substance P. In contrast, chemical ablation of..