The influence of exercise on morphological and neurochemical properties of neurons in rat nodose ganglia

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

“…The following microscopic criteria allowed a 70% likelihood of correctly identifying these neurons (Figure 2B, white arrows): 1 a rough membrane appearance restricted to the cell center. This is significantly different from myelinated A-type neurons that typically show rough appearance of the entire visible portion of the cell surface; 2 Near perfectly round shape with equal length of long axis and short axis; 3 Ah-type neurons exhibit relatively less variation in soma diameter (~50-60 μm) and whole-cell capacitance (~60 pF) in adult female rats, while the diameter and whole-cell capacitance of A-type neurons vary significantly (30-70 μM and 25-80 pF); 4 Parts of axons may still be attached to the neurons if the preparation was not enzymatically overdigested. Among there microscopic characteristics, centrally rough membrane and nearly round ship are keys for distinguish Ah-type from others; whereas, the diameter and axon attachment are considerable help in identification process (Table 3).…”

“…However, the clear disadvantage of using isolated nodose neuron preparations lies in its inability to readily identify the neuron subtype based on conduction velocity measurements in the corresponding afferent fibers, simply because afferent fibers are lost during the enzymatic isolation procedure. In order to still be able to classify neuron subtypes in isolated cell preparations, several methods have been suggested, including measurement of neuron diameter 3, sensitivity to capsaicin 4, electrophysiological characteristics [e.g., hump over the course of repolarization 5, presence of tetrodotoxin-resistant (TTX-R) Na + channels 6. The presence of a repolarization hump has long been considered a specific feature of unmyelinated C-types in isolated neuron preparations 5, 7.…”