Peripheral treatment of Aa EVs increases the excitability of nociceptive sensory neurons.

(A) Typical phase contrast (Ph; left) and fluorescence (RNA; middle, DiD; right) images of small-sized TG neurons isolated from Aa EV-injected (approximately 2.25 × 109 particles in 50 μl of PBS, epidermal injection) mice. (B) Typical raw traces of voltage-gated Na+ current observed from Aa EV-treated small-sized TG neurons in the absence (black) and presence (red) of 1 μM tetrodotoxin (TTX). Voltage-gated Na+ current was elicited by brief voltage step pulses (50 ms duration, -80 mV to -10 mV) in a voltage-clamp condition. Note that the Na+ current recorded in the presence of TTX completely disappeared by adding Na+-free extracellular solution. (C) Typical voltage traces in response to depolarizing current. Four successive raw traces elicited by 1-fold threshold (1T; 40 pA for PBS-treated neuron and 30 pA for Aa EV-treated neuron) to 4-fold threshold (4T) depolarizing current injections were shown. (D) Left, the number of action potentials elicited by depolarizing current stimuli (1T to 4T) in PBS-treated (black) and Aa EV-treated (cyan) small-sized TG neurons. Points and error bars represent the mean and SEM from 52 PBS-treated and 50 Aa EV-treated small-sized TG neurons. *; p p p < 0.05, unpaired t-test.