511.10 A subpopulation of peptidergic nociceptors in Sus scrofa domesticus is lacking hyperpolarization-activated nucleotide-gated (HCN) channels

Silent and polymodal nociceptors differ, e. g., in response patterns to electrical stimulation. One underlying mechanism could be differential expression of HCN channels, which presumably contribute to stabilizing resting membrane potential and controlling cell excitability.We used isolated DRG neurons from a non-rodent species, Sus scrofa domesticus. Neurons from piglets were investigated immunocytochemically and electrophysiologically.Single labeling revealed 54% capsaicin sensitive and 29% IB4 positive neurons; 83% expressed HCN-1 and 88% HCN-2 channels. Double labeling showed: (i) Out of the capsaicin sensitive neurons, 42% were IB4 positive, 80% were HCN-1 and 77% HCN-2 immunoreactive. (ii) Out of the HCN-1 or HCN-2 negative neurons, 94% and 97 % were capsaicin positive, 90% and 85% were IB4 negative, respectively. Triple labeling revealed that the vast majority of neurons lacking HCN channel subtypes 1 and/or 2 are capsaicin positive and IB4 negative. The soma sizes of these n...