Novel pharmacological agents known as opsinamides could potentially be used to help patients who suffer from light-sensitivity associated with migraine headaches, according to a study in the August 25 online version of Nature Chemical Biology.

These sulfonamide-derived compounds inhibit the function of melanopsin, a photopigment found in retinal ganglion cells that helps regulate circadian rhythms and pupillary light reflex. The researchers noted that melanopsin-based receptor activity is largely responsible for triggering light sensitivity in cases of migraine headache.

In a rodent study, the researchers evaluated hundreds of chemicals to determine if any effectively blocked melanopsin, but did not inhibit the function of similar receptors responsible for visual processing. After extensive testing, they determined that in vivo administration of opsinamides prevented a normal pupillary response when the mice were exposed to bright light. Further, the opsinamides appeared to have no effect on mice that were lacking melanopsin, indicating that the compounds were specifically targeting the intended receptors.

“There are many people who would like to work when they have migraine pain exacerbated by light,” says lead author Satchidananda Panda, PhD, associate professor at the Regulatory Biology Laboratory of the Salk Institute in La Jolla, Calif. “If these drugs could stop the light sensitivity associated with the headaches, it would enable them to be much more productive.”

Jones KA, Hatori M, Mure LS, et al. Small-molecule antagonists of melanopsin-mediated phototransduction. Nat Chem Biol. 2013 Aug 25. [Epub ahead of print]