TRPV1‐MEDIATED MODULATION OF SYNAPTIC INPUTS IN IDENTIFIED KIDNEY‐RELATED SYMPATHETIC PREMOTOR NEURONS IN THE ROSTRAL VENTROLATERAL MEDULLA

Abstract

The central nervous system regulates arterial blood pressure (ABP), largely by controlling actions of the sympathetic nervous activity which includes control of kidney. Synaptic balance in the neurons of the rostral ventrolateral medulla (RVLM) is a critical component in the central pathways mediating sympathetic cardiovascular regulation. Transient receptor potential vanilloid type 1 (TRPV1) are expressed in the RVLM, but cellular effects of TRPV1 activation in the RVLM are not known. Whole‐cell patch‐clamp recordings in brainstem slices were used to characterize synaptic activity of kidney‐related RVLM neurons identified using the transynaptic retrograde viral vector PRV‐152 and to test the hypothesis that activation of TRPV1 enhances synaptic inputs to these neurons. Immunohistochemical studies showed that TRPV1 receptors are distributed through RVLM and colocalized with kidney‐related RVLM neurons. Kidney‐related RVLM neurons fired action‐potentials at rest and received abundant synaptic input that could be modulated by TRPV1 agonists. Application of the TRPV1 receptor agonist, capsaicin (1 μM), increased the frequency of spontaneous IPSCs from 1.6±0.6 Hz to 4.6±1 Hz and EPCSs from 4±0.4 to 8.7±1 Hz, respectively. Capsaicin also increased action‐potential frequency in kidney‐related sympathetic premotor RVLM neurons from 3.1±0.5 Hz to 6±0.6 Hz (p<0.05). Modulation of RVLM neurons by TRPV1 agonists represents a novel means of modulating ABP and, by inference, hypertension.Supported by AHA 0865395D and NIH HL091293‐01A1