Fatty acid amide hydrolase knockout mouse genotype: molecular mechanisms & dependencies

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What it does

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Where it participates (unsigned role)

The antinociceptive effect of acetaminophen at an oral dose lacking hypolocomotor activity was absent in fatty acid amide hydrolase and TRPV1 knockout mice in the formalin, tail immersion and von Frey tests, that dose did not affect global brain contents of prostaglandin E2 or endocannabinoids, intracerebroventricular injection of AM404 produced a TRPV1-mediated antinociceptive effect in the formalin test, and pharmacological inhibition of brain TRPV1 by intracerebroventricular capsazepine abolished the antinociceptive effect of oral acetaminophen.
Human transient receptor potential vanilloid 1 / TRPV1 → Antinociception in thermal, mechanical and chemical pain tests source_derived_draftungraded
Experimental context and source evidence
availability_state
machinery_impairment Imported condition classification; unverified.
evidence_span
{"source_cache": "artifacts/paracetamol-research/20862299.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "2cb3934d80d1a7a6632c49f2007cb6e203b3851706a4ffeb43fda2bb655fa8f2", "start_char": 0, "end_char": 1701, "text_sha256": "2cb3934d80d1a7a6632c49f2007cb6e203b3851706a4ffeb43fda2bb655fa8f2"}
experimental_model
Formalin, tail immersion and von Frey tests in fatty acid amide hydrolase and TRPV1 knockout mice with intracerebroventricular injection
exposure
Oral acetaminophen at a dose lacking hypolocomotor activity, with intracerebroventricular AM404 and capsazepine
limitations
Two separate knockouts and a central antagonist all point the same way, and the dose was chosen to avoid sedation confounding the pain tests. Brain prostaglandin E2 was unchanged at that dose, which is a notable negative.
nutrient_topic
Paracetamol research collection; topical membership is not evidence of a direct clinical effect, and the drug is recorded separately from the metabolites NAPQI and AM404. · Paracetamol
organism
Mouse
plain_language
Remove the channel and the painkiller stops working, while putting the metabolite straight into the brain works.
primary_references
[apap-p20862299] TRPV1 in brain is involved in acetaminophen-induced antinociception. (2010). https://pubmed.ncbi.nlm.nih.gov/20862299/ DOI: 10.1371/journal.pone.0012748
tissue_or_cell_type
Brain
trigger_kind
machinery_impairment Imported condition classification; unverified.
Paracetamol: the enzyme it reduces rather than blocks, the isoform that turned out not to exist, the metabolite that carries the analgesia, and the metabolite that destroys the liver (2026-09-22) · lines 311–322
AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Formalin, tail immersion and von Frey tests in fatty acid amide hydrolase and TRPV1 knockout mice with intracerebroventricular injection · source_derived_draft · unverified_draft
### apap-analgesia-needs-trpv1 The antinociceptive effect of acetaminophen at an oral dose lacking hypolocomotor activity was absent in fatty acid amide hydrolase and TRPV1 knockout mice in the formalin, tail immersion and von Frey tests, that dose did not affect global brain contents of prostaglandin E2 or endocannabinoids, intracerebroventricular injection of AM404 produced a TRPV1-mediated antinociceptive effect in the formalin test, and pharmacological inhibition of brain TRPV1 by intracerebroventricular capsazepine abolished the antinociceptive effect of oral acetaminophen. Condition category: machinery_impairment nutrient_topic: Paracetamol research collection; topical membership is not evidence of a direct clinical effect, and the drug is recorded separately from the metabolites NAPQI and AM404. plain_language: Remove the channel and the painkiller stops working, while putting the metabolite straight into the brain works. organism: Mouse tissue_or_cell_type: Brain experimental_model: Formalin, tail immersion and von Frey tests in fatty acid amide hydrolase and TRPV1 knockout mice with intracerebroventricular injection limitations: Two separate knockouts and a central antagonist all point the same way, and the dose was chosen to avoid sedation confounding the pain tests. Brain prostaglandin E2 was unchanged at that dose, which is a notable negative. exposure: Oral acetaminophen at a dose lacking hypolocomotor activity, with intracerebroventricular AM404 and capsazepine evidence_span: {"source_cache": "artifacts/paracetamol-research/20862299.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "2cb3934d80d1a7a6632c49f2007cb6e203b3851706a4ffeb43fda2bb655fa8f2", "start_char": 0, "end_char": 1701, "text_sha256": "2cb3934d80d1a7a6632c49f2007cb6e203b3851706a4ffeb43fda2bb655fa8f2"} [apap-p20862299] TRPV1 in brain is involved in acetaminophen-induced antinociception. (2010). https://pubmed.ncbi.nlm.nih.gov/20862299/ DOI: 10.1371/journal.pone.0012748
Complete structured claim and evidence
Acetaminophen, following deacetylation to its primary amine, is conjugated with arachidonic acid in the brain and the spinal cord to form the potent TRPV1 agonist N-arachidonoylphenolamine, and this conjugation is absent in mice lacking the enzyme fatty acid amide hydrolase; AM404 also inhibits purified cyclooxygenase-1 and -2 and prostaglandin synthesis in lipopolysaccharide-stimulated macrophages and acts on the endogenous cannabinoid system, identifying fatty acid conjugation as a novel pathway for drug metabolism.
Paracetamol → AM404 / N-arachidonoylphenolamine source_derived_draftungraded
Experimental context and source evidence
availability_state
machinery_impairment Imported condition classification; unverified.
evidence_span
{"source_cache": "artifacts/paracetamol-research/15987694.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "8da7599ee6674ced34346ae03fae0e421bcc5c1f53b0cb879145d7a511502001", "start_char": 0, "end_char": 1093, "text_sha256": "8da7599ee6674ced34346ae03fae0e421bcc5c1f53b0cb879145d7a511502001"}
experimental_model
Brain and spinal cord metabolite identification in wild-type and fatty acid amide hydrolase knockout mice
exposure
Acetaminophen, with the conjugation step tested by genetic deletion of the conjugating enzyme
limitations
Identifies a previously unknown route of drug metabolism and proves the enzyme by knockout. The downstream activities are measured on purified enzyme and cell lines rather than in the treated animal.
nutrient_topic
Paracetamol research collection; topical membership is not evidence of a direct clinical effect, and the drug is recorded separately from the metabolites NAPQI and AM404. · Paracetamol
organism
Mouse
plain_language
The brain takes the drug apart and builds the pieces into something new, and that something is what acts.
primary_references
[apap-p15987694] Conversion of acetaminophen to the bioactive N-acylphenolamine AM404 via fatty acid amide hydrolase-dependent arachidonic acid conjugation in the nervous system. (2005). https://pubmed.ncbi.nlm.nih.gov/15987694/ DOI: 10.1074/jbc.m501489200
tissue_or_cell_type
Brain and spinal cord
trigger_kind
machinery_impairment Imported condition classification; unverified.
Paracetamol: the enzyme it reduces rather than blocks, the isoform that turned out not to exist, the metabolite that carries the analgesia, and the metabolite that destroys the liver (2026-09-22) · lines 298–309
AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Brain and spinal cord metabolite identification in wild-type and fatty acid amide hydrolase knockout mice · source_derived_draft · unverified_draft
### apap-faah-builds-am404 Acetaminophen, following deacetylation to its primary amine, is conjugated with arachidonic acid in the brain and the spinal cord to form the potent TRPV1 agonist N-arachidonoylphenolamine, and this conjugation is absent in mice lacking the enzyme fatty acid amide hydrolase; AM404 also inhibits purified cyclooxygenase-1 and -2 and prostaglandin synthesis in lipopolysaccharide-stimulated macrophages and acts on the endogenous cannabinoid system, identifying fatty acid conjugation as a novel pathway for drug metabolism. Condition category: machinery_impairment nutrient_topic: Paracetamol research collection; topical membership is not evidence of a direct clinical effect, and the drug is recorded separately from the metabolites NAPQI and AM404. plain_language: The brain takes the drug apart and builds the pieces into something new, and that something is what acts. organism: Mouse tissue_or_cell_type: Brain and spinal cord experimental_model: Brain and spinal cord metabolite identification in wild-type and fatty acid amide hydrolase knockout mice limitations: Identifies a previously unknown route of drug metabolism and proves the enzyme by knockout. The downstream activities are measured on purified enzyme and cell lines rather than in the treated animal. exposure: Acetaminophen, with the conjugation step tested by genetic deletion of the conjugating enzyme evidence_span: {"source_cache": "artifacts/paracetamol-research/15987694.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "8da7599ee6674ced34346ae03fae0e421bcc5c1f53b0cb879145d7a511502001", "start_char": 0, "end_char": 1093, "text_sha256": "8da7599ee6674ced34346ae03fae0e421bcc5c1f53b0cb879145d7a511502001"} [apap-p15987694] Conversion of acetaminophen to the bioactive N-acylphenolamine AM404 via fatty acid amide hydrolase-dependent arachidonic acid conjugation in the nervous system. (2005). https://pubmed.ncbi.nlm.nih.gov/15987694/ DOI: 10.1074/jbc.m501489200
Complete structured claim and evidence

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Fatty acid amide hydrolase knockout mouse genotype