Endocannabinoid drugs reduced anxiety but did not erase fear memories in a rat PTSD model
In rats with extinction-resistant fear (modeling PTSD), a CB1 agonist reduced anxiety-like behavior, but neither it nor an endocannabinoid-boosting drug altered the expression of conditioned fear memories.
Quick Facts
What This Study Found
Acute WIN55,212-2 (CB1 agonist) reduced anxiety in "weak extinction" rats but did not affect fear recall. The FAAH inhibitor URB597 did not reduce anxiety or fear acutely. The CB1 inverse agonist AM251 increased anxiety in normal-extinction rats. Chronic administration of neither URB597 nor AM251 altered fear or anxiety, and did not change FAAH or CB1 expression.
Key Numbers
25-30% of rats showed weak extinction (modeling PTSD). WIN55,212-2 reduced anxiety in WE rats. AM251 increased anxiety in SE rats. No drug condition altered freezing during fear recall.
How They Did This
Rats underwent fear conditioning and were segregated into weak extinction (WE, modeling PTSD) and strong extinction (SE) groups. Acute and chronic endocannabinoid-modulating drugs were tested on fear recall and novelty-suppressed feeding (anxiety measure).
Why This Research Matters
PTSD involves both anxiety and persistent fear memories. This study suggests the endocannabinoid system may help with PTSD-related anxiety but may not be sufficient to eliminate extinction-resistant fear memories.
The Bigger Picture
The distinction between anxiety and fear memory is important for PTSD treatment. Endocannabinoid-based therapies might address generalized anxiety in PTSD without necessarily helping with the core trauma memories.
What This Study Doesn't Tell Us
Animal model may not fully capture human PTSD complexity. Systemic drug administration does not target specific brain regions. Only one dose of each drug was tested. Fear recall was measured by freezing, which may not capture all aspects of fear response.
Questions This Raises
- ?Would targeted brain-region delivery of endocannabinoid drugs be more effective for fear extinction?
- ?Could combining endocannabinoid therapy with exposure therapy improve outcomes?
- ?Do different cannabinoid compounds have different effects on fear vs. anxiety?
Trust & Context
- Key Stat:
- CB1 agonist reduced anxiety but did not alter fear recall
- Evidence Grade:
- Controlled preclinical study with relevant behavioral paradigm, but systemic drug delivery and single-dose testing limit conclusions.
- Study Age:
- 2020 animal study. Helps clarify which PTSD symptoms might respond to endocannabinoid modulation.
- Original Title:
- Endocannabinoid modulating drugs improve anxiety but not the expression of conditioned fear in a rodent model of post-traumatic stress disorder.
- Published In:
- Neuropharmacology, 166, 107965 (2020)
- Authors:
- Vimalanathan, Akshayan, Gidyk, Darryl C, Diwan, Mustansir, Gouveia, Flavia V, Lipsman, Nir, Giacobbe, Peter, Nobrega, José N, Hamani, Clement
- Database ID:
- RTHC-02898
Evidence Hierarchy
Tests effects in animals (usually mice or rats), not humans.
What do these levels mean? →Frequently Asked Questions
What are weak extinction rats?
About 25-30% of rats that undergo fear conditioning fail to learn that the fear cue is no longer dangerous. These "weak extinction" rats model the extinction-resistant fear seen in PTSD.
Why did the CB1 agonist help anxiety but not fear?
Anxiety and conditioned fear involve overlapping but distinct brain circuits. The endocannabinoid system may regulate generalized anxiety more readily than deeply encoded associative fear memories.
Read More on RethinkTHC
- anxiety-leaving-house-weed-withdrawal-agoraphobia
- anxiety-response-technique-weed-withdrawal
- anxiety-toolkit-weed-withdrawal
- anxiety-worse-after-quitting-weed
- breathing-exercises-weed-withdrawal-anxiety
- cannabis-induced-anxiety
- does-weed-help-anxiety
- grounding-techniques-weed-withdrawal
- health-anxiety-weed-withdrawal
- manage-anxiety-without-weed
- quitting-weed-anxiety-disorder
- quitting-weed-anxiety-medication-ssri
- self-medicating-anxiety-with-weed
- therapy-quitting-weed-anxiety
- weed-and-anxiety
- weed-biphasic-effect-anxiety
- weed-generalized-anxiety-disorder
- weed-panic-attacks
- weed-paranoia
- weed-social-anxiety
- weed-tolerance-anxiety-stopped-working
- weed-withdrawal-anxiety
- weed-withdrawal-panic-attacks-night
- weed-withdrawal-work-anxiety
- withdrawal-anxiety-vs-real-anxiety
Cite This Study
https://rethinkthc.com/research/RTHC-02898APA
Vimalanathan, Akshayan; Gidyk, Darryl C; Diwan, Mustansir; Gouveia, Flavia V; Lipsman, Nir; Giacobbe, Peter; Nobrega, José N; Hamani, Clement. (2020). Endocannabinoid modulating drugs improve anxiety but not the expression of conditioned fear in a rodent model of post-traumatic stress disorder.. Neuropharmacology, 166, 107965. https://doi.org/10.1016/j.neuropharm.2020.107965
MLA
Vimalanathan, Akshayan, et al. "Endocannabinoid modulating drugs improve anxiety but not the expression of conditioned fear in a rodent model of post-traumatic stress disorder.." Neuropharmacology, 2020. https://doi.org/10.1016/j.neuropharm.2020.107965
RethinkTHC
RethinkTHC Research Database. "Endocannabinoid modulating drugs improve anxiety but not the..." RTHC-02898. Retrieved from https://rethinkthc.com/research/vimalanathan-2020-endocannabinoid-modulating-drugs-improve
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkTHC research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.