Role of the spinal trigeminal nucleus in the rat autonomic reflex.

The goal of the present study was to investigate the regional differences between the three subnuclei (oralis, interpolaris, and caudalis) of the spinal trigeminal nucleus (Vsp) in eliciting parasympathetic and sympathetic reflex autonomic responses. We evoked changes in lower lip blood flow (LBF) and systemic arterial blood pressure (SABP) by electrically stimulating these subnuclei in artificially ventilated, urethane-anaesthetised, cervically vago-sympathectomized rats. The LBF increases evoked by electrical stimulation of the Vsp at interpolaris were much larger than those at the sites of the oralis and caudalis. No significant difference in SABP increase was observed by Vsp stimulation between the interpolaris and caudalis, although the SABP increase evoked by electrical stimulation of the oralis was much smaller than in the interpolaris and caudalis. The present findings show that the Vsp at the interpolaris subnucleus of the Vsp participates as a relay in lingual nerve- and Vsp-evoked somato-autonomic reflex.