Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.08.07.242057v1?rss=1 Authors: Fee, C., Misquitta, K., Sibille, E., Berman, R., Coric, V., Sanacora, G., Banasr, M. Abstract: Background: Chronic stress-related illnesses, such as major depressive disorder (MDD) and post-traumatic stress disorder (PTSD), share symptomatology, including anxiety, anhedonia, and helplessness. Across disorders, neurotoxic dysregulated glutamate (Glu) signaling may underlie symptom emergence. Current first-line antidepressant drugs (ADs), which do not directly target Glu signaling, fail to provide adequate benefit for many patients and are associated with high relapse rates. Riluzole modulates glutamatergic neurotransmission by increasing metabolic cycling and modulating signal transduction. Clinical studies exploring riluzole efficacy in stress-related disorders have provided varied results. However, the utility of riluzole for treating specific symptom dimensions or as a prophylactic treatment has not been comprehensively assessed. Methods: We investigated whether chronic prophylactic riluzole (12-15/kg/day p.o.) could prevent the emergence of behavioral deficits induced by unpredictable chronic mild stress (UCMS) in mice. We assessed i) anxiety-like behavior using the elevated-plus maze, open field test, and novelty-suppressed feeding, ii) mixed anxiety/anhedonia-like behavior in the novelty-induced hypophagia test and, iii) anhedonia-like behavior using the sucrose consumption test. Z-scoring summarized changes across tests measuring similar outcomes. In a separate learned helplessness (LH) cohort, we investigated whether chronic preventative riluzole treatment could block the development of helplessness-like behavior. Results: UCMS induced an elevation in anxiety-, anhedonia-like behavior, and overall behavioral emotionality that was blocked by prophylactic riluzole. In the LH cohort, preventative riluzole blocked the development of helplessness-like behavior. Conclusion: This study supports the utility of riluzole as a prophylactic medication, and potential relapse-preventing treatment targeting anhedonia, anxiety, and helplessness symptoms associated with stress-related disorders. Copy rights belong to original authors. Visit the link for more info