Pain

Pain in vitro on multielectrode array
Request Information

Dorsal root ganglion (DRG) cultures exhibit chemical and thermal sensitivities representative of those observed in vivo and can be cultured in vitro in Axion’s multiwell microelectrode array (MEA) plates, enabling simultaneous recording of electrical activity from numerous test conditions. In combination, DRG neurons and the Maestro multiwell MEA system constitute a high-throughput in vitro platform for chronic neuropathic pain research.

The sensation of pain is transmitted from sensory nerve endings to the central nervous system by axons of peripheral neurons whose cell bodies reside in the dorsal root ganglion (DRG). Damage to these primary afferent neurons, or defects in the proteins underlying their electrical or sensing function, can cause neuropathic pain, a persistent sensation of pain associated with increased spontaneous firing of DRG neurons

MEA recordings capture the transient and persistent increases in firing rate of DRG neurons induced by capsaicin
>

Sensitivity of DRG neurons to noxious stimuli is largely caused by the TRP family of ionotropic receptors, which display differing sensitivity profiles for stimuli including chemical agents, noxious heat and cold, and changes in pH due to inflammation. Of particular relevance is the TRPV1 channel, a primary receptor for noxious heat and pH implicated in hyperthermia and inflammatory pain. Capsaicin is an active component of chili peppers, and is a chemical irritant for humans, producing a sensation of burning in any tissue with which it comes into contact. Activation of DRG neurons was conducted using capsaicin, an agonist of the TRPV1 receptor. The effect of 100 nM capsaicin on mean firing rate (MFR) of DRG neurons (1x104 cells per well) was measured on DIV 7 with Axion's MEA system.

Pain Graphics Capsaicin Transients

A) The raw voltage trace shows the increased firing resulting from capsaicin addition, with the waveform of each detected spike plotted to the right (gray), along with the mean spike waveform (black). B) Three separate stages of the capsaicin response are apparent in the plot of well-wide firing rate (N=6 wells, mean – black, +/- standard error of the mean – gray): baseline spontaneous firing, transient capsaicin-induced firing, and a persistent elevated firing that lasts for tens of minutes following the capsaicin addition. C) The bar chart represents an average over a 3 minute period for both the baseline and the persistent phases of the capsaicin response, where the firing rate was higher in the persistent phase (N=6, p = 0.0313, Wilcoxon Signed Rank Test, error bars represent standard error of the mean).

In summary, Axion's multiwell MEA system with the Neural Module recorded the significant well-wide increase in DRG firing rate after the addition of capsaicin.

 

Click here to download the Axion BioSystems Neural Activity Brochure