Relationships between the morphology and function of gastric‐ and intestine‐sensitive neurons in the nucleus of the solitary tract

Abstract

This study employed single cell recording and intracellular iontophoretic injection techniques to characterize and label gastric- and/or intestine-sensitive neurons in the rat nucleus of the solitary tract (NST). It was possible to divide our sample of NST neurons into three broad groups based on their response to increased intra-gastric and intra-duodenal pressure. Group 1 cells (N = 14) were excited by duodenal distention but were not responsive to gastric stimulation. Most of these intestine-sensitive neurons exhibited a delayed tonic response to the stimulus. Group 2 neurons (N = 13) were excited by gastric distention but were not sensitive to distention of the duodenum. The typical Group 2 neuron evidenced a rapid, phasic response to the distention stimulus. Group 3 neurons (N = 29) responded to both gastric and duodenal stimulation. We found that the Group 2 neurons had greater dendritic length and more dendritic branch segments than the Group 1 or Group 3 neurons. Most of the Group 1 neurons were found in the subpostremal/commissural region of the NST, while the majority of the Group 2 neurons were in the gelatinous subnucleus and a disproportionate number of the Group 3 neurons were located in the medial subnucleus. The results of this investigation demonstrate that 1) there are relationships between the morphology and physiology of distention-sensitive neurons in the NST, and 2) there are distinct functional differences between the gelatinous, medial and commissural subnuclei of this nucleus.

Presynaptic Melanocortin-4 Receptors on Vagal Afferent Fibers Modulate the Excitability of Rat Nucleus Tractus Solitarius Neurons

“…The NTS comprises a vast array of neurons with different neurochemical and morphological properties (Zhang et al, 1995;Blessing, 1997;Deuchars et al, 2000;Paton et al, 2000;Travagli et al, 2006). Recently, Bailey et al (2006a) correlated morphological and electrophysiological properties of NTS neurons with their projections to either the hypothalamus or the CVLM area.…”

Electrophysiological and morphological heterogeneity of rat dorsal vagal neurones which project to specific areas of the gastrointestinal tract

“…but also in their somata size or shape (Zhang et al 1995;Fogel et al 1996;Jarvinen & Powley, 1999). Fogel et al (1996) have recently provided strong evidence for the existence of a relationship between structure and function in the DMV.…”

Characterization of neurons of the nucleus tractus solitarius pars centralis

“…In particular, Smith's group reported that NTS neurons receiving sensory information from the corpus can be classified into three subgroups [14]. The vast heterogeneity of morphological features of gastrointestinal NTS neurons was reinforced further by studies of Fogel's group, which classified NTS neurons into three subpopulations based upon their different responses to gastrointestinal stimulations [34].…”

“…Some membrane properties of cNTS neurons, however, seem to indicate that these neurons have characteristics that distinguish them from other NTS neurons, most noticeably the smaller soma area and the higher input resistance [12,14,17,19,26,32,34]. These electrophysiological membrane features would seem to be best suited to signaling the fast dynamic changes in esophageal pressure observed during the passage of a bolus in the esophagus, since even minute changes in neurotransmitter release would induce large changes in the membrane potential.…”

“…Various groups have reported recently that NTS neurons display a certain degree of morphological and electrophysiological diversity [12,14,[18][19][20]26,34]. These observations suggest that it may be possible to differentiate between neurons subserving similar functions from adjacent neurons devoted to different roles.…”