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’s 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.
Significance Statement Riluzole is a glutamate-modulating drug with mixed evidence of efficacy in clinical studies of patients with stress-related disorders. Based on evidence suggesting that glutamatergic dysfunction contributes to the pathogenesis of stress-related disorders, we investigated whether prophylactic treatment with riluzole could prevent the onset of behavioral deficits induced by unpredictable chronic mild stress or learned helplessness in mice. Riluzole effectively prevented the emergence of anxiety-, anhedonia-like behavior, and overall behavioral emotionality in mice exposed to unpredictable chronic mild stress. In a separate cohort, riluzole blocked the emergence of helplessness-like behavior as measured in an active avoidance paradigm. These results support testing riluzole as a prophylactic treatment strategy in stress-related illnesses such as major depressive disorder or post-traumatic stress disorder.
- Riluzole
- Chronic Stress
- Prophylactic
- Depression
- Antidepressants
Competing Interest Statement
G.S. has received consulting fees from Allergan, Alkermes, AstraZeneca, Avanier, Axsome Therapeutics, Pharmaceuticals, Biohaven Pharmaceuticals, Bristol-Myers Squibb, Clexio Biosciences, EMA Wellness, Epiodyne, Intra-Cellular Therapies, Janssen, Lundbeck, Merck & Co., Minerva pharmaceuticals, Navitor, Neurocrine biosciences, NeruoRx, Novartis, Noven Pharmaceuticals, Otsuka, Perception Neuroscience, Praxis Therapeutics, Sage Pharmaceuticals, Servier Pharmaceuticals, Taisho Pharmaceuticals, Teva, Valeant, and Vistagen therapeutics over the last 36 months. He has also received additional research contracts from AstraZeneca, Bristol-Myers Squibb, Eli Lilly, Johnson & Johnson, Hoffman La-Roche, Merck & Co., and Usona over the last 36 months. Free medication was provided to GS for an NIH-sponsored study by Sanofi-Aventis. In addition, he holds shares in BioHaven Pharmaceuticals Holding Company and is a co-inventor on a patent Glutamate agents in the treatment of mental disorders (Patent number: 8778979), and a U.S. Provisional Patent Application No. 047162-7177P1 (00754) filed on August 20, 2018 by Yale University Office of Cooperative Research OCR 7451 US01. RMB and VC are employees and stockholders of Biohaven Pharmaceuticals. R.M.B. and V.C. are employees of Biohaven Pharmaceuticals.
Footnotes
↵a Shared First-authors
Research Focus: (1) Neuropsychopharmacology - behavioral < Preclinical, (2) Psychopathology – animal models < Preclinical, (3) Neuropsychopharmacology - Other < Treatment