HCN2 seems to be expressed in the enteric nervous system in rodents. It is also expressed in spinal dorsol horn neurons and is implicated in neuropathic pain. See attached links and below publications. There may well be further HCN2 expression throughout the peripheral nervous system that I'm not aware of.

Tu H, Deng L, Sun Q, Yao L, Han JS, Wan Y (2004) Hyperpolarization-activated, cyclic nucleotide-gated cation channels: roles in the differential electrophysiological properties of rat primary afferent neurons. J Neurosci Res 76:713–722

Antal M, Papp I, Bahaerguli N, Veress G, Vereb G (2004) Expression of hyperpolarization-activated and cyclic nucleotidegated cation channel subunit 2 in axon terminals of peptidergic nociceptive primary sensory neurons in the superficial spinal dorsal horn of rats. Eur J NeuroSci 19:1336–1342

Papp I, Szucs P, Hollo K, Erdelyi F, Szabo G, Antal M (2006) Hyperpolarization-activated and cyclic nucleotide-gated cation channel subunit 2 ion channels modulate synaptic transmission from nociceptive primary afferents containing substance P to secondary sensory neurons in laminae I-IIo of the rodent spinal dorsal horn. Eur J NeuroSci 24:1341–1352

http://www.sciencedirect.com/science/article/pii/S0306452204007250

http://link.springer.com/article/10.1007%2Fs11064-008-9717-6

http://www.sciencemag.org/content/333/6048/1462

Thanks!