Respiratory actions of tachykinins in the nucleus of the solitary tract: Effect of neonatal capsaicin pretreatment

Abstract

1. The respiratory response to microinjection of capsaicin and tachykinin receptor agonists into the commissural nucleus of the solitary tract (cNTS) was investigated in adult, urethane-anaesthetized rats which had been pretreated with capsaicin (50 mg kg-1 s.c.) or vehicle (10% Tween 80, 10% ethanol in saline) as day 2 neonates. 2. Microinjection of capsaiein (1 nmol) into the cNTS of vehicle-pretreated rats, significantly reduced respiratory frequency (59 breaths min-1, preinjection control, 106 breaths min-1) without affecting tidal volume (VT). In capsaicin-pretreated rats, the capsaicin-induced bradypnoea was markedly attenuated (minimum frequency, 88 breaths min-1; control, 106 breaths..