Patients wholly appreciate the shots of local anesthetic they receive before a usually minor, but otherwise painful procedure; however, no one enjoys the numb and swollen feeling that results from the anesthetic blocking all other sensations in addition to pain. An anesthetic that blocks only the pain sensations would require a command over the particular nerve fibers that transmit pain. Such a discovery would benefit patients by reducing the recovery time required after a procedure.
Researchers at UCSF have discovered molecules that may contribute greatly to the discovery of an anesthetic that only blocks pain sensations, among many other possibly profound uses. The study was led by researchers in the lab of David Julius, PhD and published on June 6, 2016 in the journal Nature.
The molecules come from a West African tarantula, the Heteroscodra maculata. The tarantula’s bite causes excruciating pain, in part, by triggering a specific kind of sodium channel within A-delta nerve fibers. This finding has implications for further progress in research for Alzheimer’s and epilepsy, for example, because the new toxins can be used as a highly selective tool to control the sodium channels of A-delta nerve fibers.
The tarantula’s venom came of interest when it was realized that it affects sodium channels, but the researchers did not originally know which of the dozens of chemicals in the tarantula’s venom specifically targeted the sodium channels. In order to identify the correct chemicals, the researchers separated the venom’s components and applied the components one-by-one to sensory neurons in a lab dish. Two peptide molecules specifically and powerfully activated the nerves and further experiments with artificial versions of the suspected molecules confirmed their effects.
Dr. Julius’s lab is renowned for its work with pain pathways and has recently been studying venom from a variety of organisms – scorpions, centipedes, and poisonous spiders – in order to better understand pain nerves.
For more information: https://www.ucsf.edu/news/2016/06/403166/tarantula-toxins-offer-key-insights-neuroscience-pain