Cephalgia is a group of headaches or migraines caused by nerve pain. SD brings out intracellular changes and polarizes the neurons in underlying areas. But its role in causing cephalgia is not established. Previous SD induction methods were invasive. In this study, non-invasive SD is induced to study behavioral changes. The objective of the study is to understand the SD-cephalgia association.
An innovative, optogenetic SD method is utilized. Male and female mice were induced with a single event SD. They also repeatedly receive SD every other day for two weeks. Endpoints like periorbital and hind paw mechanical allodynia were examined. The mice’s grimace, anxiety, and working memory were also assessed.
The single SD induction caused periorbital, bilateral, mechanical allodynia. It developed within 1 hour and resolved within two days. The symptoms were prevented by the immediate usage of the sumatriptan drug. Repeated SD also produced similar allodynia for four days, and resolved within two weeks. It also increased grimace and anxiety scores, but not hind paw withdrawal thresholds. Neither single nor repeated SD affected visuospatial working memory. There was no sexual dimorphism at any stage.
The data shows a correlated relationship between SD, anxiety, and trigeminal pain. SD possibly modulates the hypothalamic, thalamic, and limbic mechanisms.