Subtype Identification in Acutely Dissociated Rat Nodose Ganglion Neurons Based on Morphologic Parameters

Abstract

Nodose ganglia are composed of A-, Ah- and C-type neurons. Despite their important roles in regulating visceral afferent function, including cardiovascular, pulmonary, and gastrointestinal homeostasis, information about subtype-specific expression, molecular identity, and function of individual ion transporting proteins is scarce. Although experiments utilizing the sliced ganglion preparation have provided valuable insights into the electrophysiological properties of nodose ganglion neuron subtypes, detailed characterization of their electrical phenotypes will require measurements in isolated cells. One major unresolved problem, however, is the difficulty to unambiguously identify the subtype of isolated nodose ganglion neurons without current-clamp recording, because the magnitude of conduction velocity in the corresponding afferent fiber, a reliable marker to discriminate subtypes in situ, can no longer be determined. Here, we present data supporting the notion that application of an algorithm regarding to microscopic structural characteristics, such as neuron shape evaluated by the ratio between shortest and longest axis, neuron surface characteristics, like membrane roughness, and axon attachment, enables specific and sensitive subtype identification of acutely dissociated rat nodose ganglion neurons, by which the accuracy of identification is further validated by electrophysiological markers and overall positive predictive rates is 89.26% (90.04%, 76.47%, and 98.21% for A-, Ah, and C-type, respectively). This approach should aid in gaining insight into the molecular correlates underlying phenotypic heterogeneity of nodose ganglia. Additionally, several critical points that help for neuron identification and afferent conduction calibration are also discussed.

Gender Differences in Histamine-Induced Depolarization and Inward Currents in Vagal Ganglion Neurons in Rats

“…These major findings may explain, at least in part, that histamine could be a key player in gender-based differences in autonomic reflex function under physiological and disease conditions 5, 6. Consistent with our previous observation 34, a very low percentage of likely myelinated Ah-type neurons from male rats were verified using standard validation 32 and morphological parameters 33 in this investigation. However, male Ah-types do not follow the same pharmacological tendency 34 as female Ah-types regarding positive reactivity to αβ-methyl-adenosine triphosphate and negative reactivity to capsaicin.…”

Potentiation of 17β-estradiol on neuroexcitability by HCN-mediated neuromodulation of fast-afterhyperpolarization and late-afterdepolarization in low-threshold and sex-specific myelinated Ah-type baroreceptor neurons via GPR30 in female rats

“…To answer this question, BRNs were isolated from adult female rats and individually identified electrophysiologically and fluorescently [9,10]. Our results showed that, in the presence of 1.0 μM 17β-E 2 , repetitive discharge evoked by step depolarization of Ah-type BRNs was significantly enhanced in a time-dependent fashion through all stimulus intensity applied ( Fig.…”

Unique Expression of Angiotensin Type-2 Receptor in Sex-Specific Distribution of Myelinated Ah-Type Baroreceptor Neuron Contributing to Sex-Dimorphic Neurocontrol of Circulation

“…To answer this question, the single-cell real time-polymerase chain reaction (RT-PCR) was performed on electrophysiologically 14 and morphologically 26 identified A-, Ah-, and C-type BRNs isolated from adult female rats. 23 As shown in Figure 2C and 2D, all neuronal subtypes expressed both AT 1 R and AT 2 R, whereas the averaged expression level of AT 1 R was ≈4× to 5× higher in A-type neurons than that in Ah-or C-type neurons, and AT 2 R expression level was ≈7-fold higher in Ah-type neurons compared with A-or C-type neurons.…”