Scientists working at The University of Adelaide (South Australia) have discovered that a specific peptide within certain spider venom can be used to understand how people sense pain.
Specifically, the researchers found that two toxins, from the tarantula species Heteroscodra maculata, target Nav 1.1, a voltage-gated sodium channel in the body’s nervous system. When activated, this initiates the electrical impulses that signal pain. The toxins were identified as delta-theraphotoxin-Hm1a and delta-theraphotoxin-Hm1b.
Heteroscodra maculata can reach leg-spans of up to 5 inches. These hairy arachnids are characterized by their chalky white coloration with mottled black and brown markings. The spider possess potent venom (a form of toxin secreted by the tarantula.)
Importantly, the researchers discovered that Nav 1.1 contributed to mechanical, but not thermal, pain signalling. Explaining the implications, Associate Professor Stuart Brierley told the newspaper the South Australian: “Using the highly specific peptide in the spider toxin we were able to work out how pain nerve fibers signal in a healthy situation and also in chronic abdominal pain such as what you see in Irritable Bowel Syndrome (IBS).”
Further study shows that the spider toxin was capable of triggering far more pain in the IBS state than what it was in the healthy state. The reason why this carries important implications is because further research could lead to treatments for IBS based pain – blockers for Nav 1.1. These new treatments could target the peripheral nervous system only, leaving the central nervous system unaffected.
IBS refers to group of symptoms — including abdominal pain and changes in the pattern of bowel movements — without any evidence of underlying damage. The causes are unknown, and the effectiveness of short-term treatments varies.
The research has been published in the journal Nature. The study is titled “Selective spider toxins reveal a role for the Nav1.1 channel in mechanical pain.”
