Integrate Analysis of Blood Pressure Regulation System in CNS.

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The carotid sinus reflex of the blood pressure is transmitted to the nucleus of the solitary tract (NTS) via baroreceptor nerve terminals in the aortic depressor nerve (ADN) which is located in the aortic arch. However, not only the detailed mechanisms on synapse transmission in the NTS neurons projected from ADN but also modulations of vasomotor reflex have not been clarified.In the present studies, the NTS neurons projected from ADN were identified 3-5 days after injection of Di-1 to the separated ADN.This ADN axon from nodose ganglion entered the brainstem to form the solitary tract (ST) and terminated the soma and dendrites of medial NTS neurons, which released glutamate. The identified medial NTS neurons were sensitive to kainate application by 2-fold relative to the non-projected neurons from ADN.ST evoked mono-synaptic glutamatergic responses were mediated by non-NMDA glutamate receptors in the medial NTS neurons. Furthermore, both capsaicin, a VR-1 (vanilloid) receptors agonist and a, b met ATP, a purinergic P2X3 receptors agonist, increased glutamate release 30-fold relative to the control value in dissociated medial NTS neurons, Which is suggested that vasodilation is manipulated capsaicin and ATP at brainstem level.This functional VR-1 and purinergic regulation might play an important role for any systemic therapies since NTS is exposed to an open blood brain barrier.