Abstract
Purpose :
E-series resolvins (Rv), derived from the n-fatty acid, eicosapentaenoic acid (EPA), and the D-series Rvs, protectins, and maresins all derived from the n-fatty acid docosahexaenoic acid (DHA), comprise three categories of specialized pro-resolving mediators (SPMs) that actively resolve inflammation in disease. The purpose of this study was to determine if one or more of these SPM families can attenuate the capsaicin-evoked activity of rat trigeminal ganglion neurons indicating a decrease in corneal pain.
Methods :
Rat trigeminal ganglia (TG) were extracted and dissociated first in a solution of papain in HBSS for 20 minutes before transferred to a solution of collagenase and dispase for a further 20 minutes. The dissociated cells were then separated using a percoll density gradient. The TG neurons were isolated and plated onto poly-L-lysine and laminin coated glass-bottom dishes and left to grow overnight. The following day, cells were washed with Krebs Ringer Buffer (KRB) and loaded with the calcium-sensitive fluorescent dye fura2. An increase in intracellular [Ca2+] indicated activation of the neuron and pain in the nerve endings. Thirty minutes prior to the experiment cells were treated with one of the following: RvD1, RvD2, RvD3, RvD4, RvD5, or RvE1 at concentrations between 10-11M and 10-8M. The cells were then stimulated with capsaicin (10-7M) and intracellular [Ca2+] were recorded over time.
Results :
Pre-treatment with RvD1 10-8M reduced the magnitude of the capsaicin-induced calcium influx by an average of 36.03% (N=7 p=0.013). RvD2 10-11, 10-10, 10-9, and 10-8M reduced the magnitude of the response by an average of 49.29%, 49.57%, 35.64% and 63.58% respectively (N=7, p= 0.001, 0.002, 0.001, and 0.001 respectively). RvD3 10-8M inhibited the response by an average of 25.05% (N=4, p =0.003). RvD5 10-9M inhibited the response by an average of 59.93% (N=4, p= 0.003). RvE1 10-10M significantly reduced intracellular Ca2+ influx following capsaicin administration by an average of 19.32% (N=4, p=0.042).
Conclusions :
The SPMs RvD1, RvD2, RvD3, RvD5, and RvE1 significantly decrease capsaicin-evoked intracellular [Ca2+] influx in rat TG, with RvD2 being the most potent SPM treatment could decrease ocular surface pain.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.