Meeting Abstract
P3.150 Sunday, Jan. 6 Topographical variability of pain sensitivity in grasshopper mice: a preliminary analysis. BRUMLOW, C*; ROSE, V; ROWE, A; ROWE, M; , ; , ; , ; , ; , ; , ; , ; , ; Sam Houston State; Huntsville High School, TX; Univ. Texas, Austin; Sam Houston State ceg012@shsu.edu
Bark scorpions (Centruroides spp.) are known for possessing extremely painful, neurotoxic venom that can be lethal to vertebrates, including humans. Grasshopper mice (Onychomys spp.) feed readily on bark scorpions, protected by structural changes in the voltage-gated sodium channels in the mice’s peripheral nerves and muscles that are the targets of bark scorpion toxins. These structural changes include mutations in the mice’s nociceptors (i.e., pain-sensing neurons), resulting in stings that are briefly irritating to the mice but do not lead to aversive conditioning. Anecdotal observations from previous feeding studies suggest an additional adaptation enabling the mice to feed on bark scorpions – stings delivered to the facial region of a mouse appear to induce less grooming than stings landing elsewhere on the mouse’s body. These observations suggest there are topographical differences in the expression of the structurally modified sodium channels responsible for the mice’s resistance to the scorpion’s pain-inducing toxins. For example, nociceptors in the face of the mouse (trigeminal ganglia neurons) may express more of the resistant channels than nociceptors innervating tissue from the rest of the body (dorsal root ganglia neurons). We are currently re-examining videotapes from our earlier feeding trials. For each mouse, we are recording the topographical location of each sting (face vs. body), as well as the amount of time the mouse grooms the site of the sting. Results showing that the mice receive most of the stings to the face, and that such stings are less irritating than stings to the body, would provide preliminary evidence suggesting adaptive topographical differences in pain sensitivity in grasshopper mice.
