Dedicated C-fiber vagal sensory afferent pathways to the paraventricular nucleus of the hypothalamus
| Autor: | Jessica A. Fawley, Michael C. Andresen, Deborah M. Hegarty, Sue A. Aicher, Eric Beaumont |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2021 |
| Předmět: |
Male
Patch-Clamp Techniques Resiniferatoxin TRPV Cation Channels Solitary tract nucleus Article Rats Sprague-Dawley chemistry.chemical_compound medicine Solitary Nucleus Animals Molecular Biology Afferent Pathways Nerve Fibers Unmyelinated musculoskeletal neural and ocular physiology General Neuroscience digestive oral and skin physiology Solitary tract Excitatory Postsynaptic Potentials Vagus Nerve respiratory system Vagus nerve Rats medicine.anatomical_structure nervous system chemistry Hypothalamus Synapses Excitatory postsynaptic potential Neurology (clinical) Brainstem Diterpenes Nucleus Neuroscience circulatory and respiratory physiology Developmental Biology Paraventricular Hypothalamic Nucleus |
| Zdroj: | Brain Res |
| Popis: | The nucleus of the solitary tract (NTS) receives viscerosensory information from the vagus nerve to regulate diverse homeostatic reflex functions. The NTS projects to a wide network of other brain regions, including the paraventricular nucleus of the hypothalamus (PVN). Here we examined the synaptic characteristics of primary afferent pathways to PVN-projecting NTS neurons in rat brainstem slices. Expression of the Transient Receptor Potential Vanilloid receptor (TRPV1+) distinguishes C-fiber afferents within the solitary tract (ST) from A-fibers (TRPV1−). We used resiniferatoxin (RTX), a TRPV1 agonist, to differentiate the two. The variability in the latency (jitter) of evoked excitatory postsynaptic currents (ST-EPSCs) distinguished monosynaptic from polysynaptic ST-EPSCs. Rhodamine injected into PVN was retrogradely transported to identify PVN-projecting NTS neurons within brainstem slices. Graded shocks to the ST elicited all-or-none EPSCs in rhodamine-positive NTS neurons with latencies that had either low jitter (200 μs - polysynaptic inputs) or both. RTX blocked ST-evoked TRPV1+ EPSCs whether mono- or polysynaptic. Most PVN-projecting NTS neurons (17/21 neurons) had at least one input polysynaptically connected to the ST. Compared to unlabeled NTS neurons, PVN-projecting NTS neurons were more likely to receive indirect inputs and be higher order. Surprisingly, sEPSC rates for PVN-projecting neurons were double that of unlabeled NTS neurons. The ST synaptic responses for PVN-projecting NTS neurons were either all TRPV1+ or all TRPV1−, including neurons that received both direct and indirect inputs. Overall, PVN-projecting NTS neurons received direct and indirect vagal afferent information with strict segregation regarding TRPV1 expression. |
| Databáze: | OpenAIRE |
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