Happy Holidays! Journal Club will be a bit earlier than usual this month as everyone will be busy celebrating the holidays soon. Dr. Medvedik wanted to take a look at something a bit different this month. We are taking a look at a fascinating study where researchers used light to treat Alzheimer’s plaque formation in mice. This is considerably different to more traditional approaches to treat this disease so we thought we would take a look at the study and discuss the findings.
Changes in gamma oscillations (20–50 Hz) have been observed in several neurological disorders. However, the relationship between gamma oscillations and cellular pathologies is unclear. Here we show reduced, behaviourally driven gamma oscillations before the onset of plaque formation or cognitive decline in a mouse model of Alzheimer’s disease. Optogenetically driving fast-spiking parvalbumin-positive (FS-PV)-interneurons at gamma (40 Hz), but not other frequencies, reduces levels of amyloid-β (Aβ)1–40 and Aβ 1–42 isoforms. Gene expression profiling revealed induction of genes associated with the morphological transformation of microglia, and histological analysis confirmed increased microglia co-localization with Aβ. Subsequently, we designed a non-invasive 40 Hz light-flickering regime that reduced Aβ1–40 and Aβ1–42 levels in the visual cortex of pre-depositing mice and mitigated plaque load in aged, depositing mice. Our findings uncover a previously unappreciated function of gamma rhythms in recruiting both neuronal and glial responses to attenuate Alzheimer’s-disease-associated pathology.
Iaccarino, H. F., Singer, A. C., Martorell, A. J., Rudenko, A., Gao, F., Gillingham, T. Z., … & Adaikkan, C. (2016). Gamma frequency entrainment attenuates amyloid load and modifies microglia. Nature, 540(7632), 230-235.
Unfortunately, the paper is behind an expensive paywall on nature, so if like us you agree that science, and in particular knowledge pertaining to health, should not be behind paywalls grab the paper for free at Sci-hub.