Study reveals what’s behind the king baboon spider’s painful bite
- King Baboon spider is a large African tarantula scientifically named Pelinobius muticus.
- The spider usually has dark brown to orange coloration and lives in grasslands and shrublands of east Africa.
- It has been reported that the spider’s bite can cause severe pain, swelling, itchiness, and muscle cramping.
- Hyperalgesia, an abnormal increase sensitivity to pain, is the most well-known symptom after a bite from king baboon spider.
- However, the molecular basis by which the venom induces the severe pain is not well understood.
- Analysis of the venom revealed that a cysteine-rich peptide called δ/κ-theraphotoxin-Pm1a (δ/κ-TRTX-Pm1a) induced nocifensive behavior when injected into mice.
- Nocifensive behavior is the response of an animal to very unpleasant or painful stimuli.
- When a synthetic version of the peptide was introduced into the small dorsal root ganglion neurons, hyperexcitability was observed.
- During the excessive excitation, tetrodotoxin-resistant sodium currents were enhanced, repolarization was impaired, and the threshold of action potential firing was lowered, all consistent with the severe pain associated with venomous bite.
- The molecular mechanism of nociceptor sensitization by the cysteine-rich peptide involves several modes of actions over several ion channel targets.
- The unselective targeting approach of the peptide may be an evolutionary adaptation in pain-causing defensive venom.
Rocio K. Finol-Urdaneta, Rebekah Ziegman, Zoltan Dekan, Jeffrey R. McArthur, Stewart Heitmann, Karen Luna-Ramirez, Han-Shen Tae, Alexander Mueller, Hana Starobova, Yanni K.-Y. Chin, Joshua S. Wingerd, Eivind A. B. Undheim, Ben Cristofori-Armstrong, Adam P. Hill, Volker Herzig, Glenn F. King, Irina Vetter, Lachlan D. Rash, David J. Adams, Paul F. Alewood Proceedings of the National Academy of Sciences Feb 2022, 119 (5) e2110932119; DOI: 10.1073/pnas.2110932119. https://www.pnas.org/content/119/5/e2110932119