Evidence map›Paper›PMID 41965551›Full record

ArticleThe journal of headache and pain2026

Distribution and subacute modulation of endocannabinoid metabolizing enzymes in the trigeminal complex and midbrain in a pre-clinical model of post-traumatic headache.

Gurueswar Nagarajan, Yumin Zhang

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Article in The journal of headache and pain, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Not yet cited in PubMed.

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5 · Who and what money

Authors and funding

2 authors.

Gurueswar NagarajanHenry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD, 20814, USA.
Yumin ZhangDepartment of Anatomy, Physiology and Genetics, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD, 20814, USA. yumin.zhang@usuhs.edu.

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

Abstract

backgroundPost-traumatic headache (PTH) is a debilitating neurological sequela of mild traumatic brain injury (mTBI) characterized by secondary cephalic pain. The endocannabinoid system (ECS) is a critical modulator of nociception, yet the specific spatiotemporal changes in its metabolic machinery within cephalic pain circuits following mTBI are poorly understood.

methodsUsing in-situ hybridization (ISH), we first characterized the levels of gene expression of major endocannabinoid (eCB) synthesizing enzymes (Napepld, Gde1, Dagla, Daglb), hydrolyzing enzymes (Faah, Mgll) and cannabinoid receptors (Cnr1 and Cnr2) in the trigeminal complex (trigeminal ganglion - TG, trigeminal root entry zone - TREZ, and trigeminal nucleus caudalis - TNC) and midbrain (periaqueductal gray - PAG, dorsal raphe - DR) regions involved in the modulation of pain. Subsequently, employing a mouse model of repetitive closed head mTBI that induces cephalic pain, we assessed global eCB enzymatic gene expression changes via qPCR and region-specific changes via ISH at one-week post-injury.

resultsBaseline characterization revealed complex co-expression patterns, with Gde1 and Daglb transcripts being significantly more abundant than Napepld and Dagla in the TG, TNC, and PAG. Seven days post-mTBI, coinciding with the onset of PTH-like symptoms, we identified a significant upregulation of the hydrolyzing enzymes Faah in the peripheral TREZ but not in the TG sensory neurons. Centrally, although no difference was observed in the TNC, mTBI induced an upregulation of Mgll in the ventrolateral PAG (vlPAG) and the DR, particularly within DR VGlut3+ neurons.

conclusionThese findings demonstrate a novel neuropathological mechanism whereby mTBI triggers a persistent, region-specific upregulation of genes encoding eCB-degrading enzymes. Thus, sub-acute modulation of eCB hydrolyzing enzymes in critical peripheral and central pain-modulating regions may contribute to the maintenance of cephalic pain associated with mTBI. CLINICAL TRIAL NUMBER: Not applicable.

Indexed as

EndocannabinoidsMesencephalonPost-Traumatic HeadacheTrigeminal GanglionAnimalsDisease Models, AnimalMaleMiceMice, Inbred C57BLEndocannabinoidsEndocannabinoid systemHydrolyzing enzymesMidbrainMild traumatic brain injuryTrigeminal complex

Identifiers

PMID41965551
PMCPMC13097742

What Socratic holds

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LicenceCC BY
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Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the Socratic graph.