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CNR1 / Cannabinoid receptor 1 · IHC design guide
Design Immunohistochemistry for CNR1
Plan CNR1 staining in paraffin sections using adipocytes and anterior pituitary cells as high-staining references (HPA tissue IHC). Assess cytoplasmic and membranous staining with the catalog antibody at 0.5–1 μg/mL (HPA tissue IHC; datasheet A01291-1).
Evidence assembled Oct 2026 · For research use; verify linked source records and product datasheet before use
CNR1 Immunohistochemistry Experimental Design Guide
Expected localisation, validated protocols, controls and antibodies — the at-a-glance facts below, then the full design guide.
Must know before staining
| Expected localisation | Cytoplasmic and membranous tissue staining (HPA tissue IHC) | |
| Staining pattern | Cytoplasmic and membranous; abundant in adipocytes (HPA tissue IHC) | |
| Antigen retrieval | Citrate pH 6 HIER, heat-mediated (datasheet A01291-1) | |
| Positive control | Adipose tissue+4 more · see all | |
| Negative control | Adrenal gland+4 more · see all |
Important caveats
Reasons your staining may differ from the expected pattern.
| Fixation | Keep fixation consistent across paraffin sections (standard IHC practice; not target-specific) | |
| Caveat | Antibody staining and RNA show medium consistency (HPA tissue IHC) | |
| Regulation | Isoforms 2 and 3 have much lower expression than isoform 1 (UniProt) | |
| Isoform / epitope | 3 isoforms; check epitope against the extracellular and cytoplasmic map (UniProt) |
Section 1
Recommended CNR1 IHC & IF Protocols
The catalog antibody’s IHC-P protocol is paired with published CNR1 chromogenic IHC protocols for placenta and monkey cerebrum (PMC12984115; PMC9496684).
| Sample | Paraffin-embedded mouse small intestine tissue; fixative not specified (datasheet A01291-1) |
| Fixation | Image fixative and duration unreported (datasheet A01291-1); verify before use. |
| Sectioning | 4–5 µm sections on charged slides (standard) |
| Deparaffinisation | Xylene, graded ethanol series to water (standard) |
| Antigen retrieval | Heat retrieval: Citrate pH 6, 20 min (datasheet A01291-1) |
| Peroxidase block | 3% H2O2, 10 min, room temperature (standard) |
| Blocking | 10% goat serum (datasheet A01291-1) |
| Primary antibody | Rabbit anti-CNR1, 0.5-1μg/ml (datasheet A01291-1) |
| Primary incubation | Overnight at 4 °C (datasheet A01291-1) |
| Detection | Streptavidin-biotin complex (SABC), DAB chromogen (datasheet A01291-1) |
| Counterstain | Hematoxylin, blue, dehydrate and mount (standard) |
| Expected result | CNR1-positive staining in adipocytes of adipose tissue (HPA tissue IHC: High). HPA tissue profile: Cytoplasmic and membranous expression in several different tissue types, most abundant in adipocytes, pituitary gland and CNS. No signal in the no-primary control. |
💡Decision noteStart with heat-mediated citrate retrieval at pH 6 for the catalog antibody (datasheet: A01291-1); evaluate the published higher-pH retrieval conditions if needed (PMC12984115; PMC9496684).
Section 2
What Is the Expected CNR1 Staining Pattern?
CNR1 is a seven-transmembrane receptor associated with the cell membrane, axons and presynaptic sites (UniProt P21554 topology/localisation). In tissue sections, expect cytoplasmic and membranous staining, especially in adipocytes and anterior pituitary cells; caudate neuronal cells show a lower reported level (HPA tissue IHC). HPA rates its tissue staining Enhanced, while noting medium consistency with RNA data and staining in some unannotated cells or structures (HPA tissue IHC).
| Strong staining outlines adipocytes or accompanies their cytoplasm; anterior pituitary cells also stain strongly (HPA: High in adipocytes and anterior pituitary cells). | This matches reported tissue IHC. Score the identified cells and their compartments, rather than treating every stained area as CNR1 positive; HPA also reports staining in unannotated structures (HPA tissue IHC). |
| A predominantly nuclear signal appears, with little membranous or cytoplasmic staining. | Nuclear dominance conflicts with the reported tissue pattern and receptor topology (HPA tissue IHC; UniProt P21554 topology). Check morphology and controls before interpreting it as CNR1; nuclear signal alone is insufficient. |
| Alveolar cells or cardiomyocytes stain as strongly as the positive tissue on the same run (HPA: Not detected in alveolar cells and cardiomyocytes). | That cell-type mismatch raises concern for cross-reactivity or detection background. HPA's negative calls apply to the named cells, not every cell in lung or heart; compare matched controls before rejecting the stain (HPA tissue IHC). |
| Colour spreads across stroma, empty spaces or many unrelated cell types, obscuring cell borders. | A diffuse field cannot establish the reported cell-specific pattern (HPA tissue IHC). Assess background on a no-primary control and inspect whether signal tracks tissue edges, deposits or endogenous detection activity. |
| Adipocytes and anterior pituitary cells lack detectable signal despite intact tissue morphology (HPA: High in both cell populations). | The expected positive reference has failed for this run. Review the antibody's IHC validation, section handling and detection controls before concluding that the specimen lacks CNR1; HPA tissue staining is a reference, not a guarantee for every section (HPA tissue IHC). |
💡Expected CNR1 appearanceA convincing positive shows membranous and cytoplasmic signal in adipocytes or anterior pituitary cells at the reported High level, with caudate neuronal cells potentially Medium; dominant nuclear colour or equally strong staining in HPA-negative cell types warrants investigation (HPA tissue IHC; UniProt P21554 localisation).
| Receptor topology and compartment | CNR1 spans the membrane 7 times and has an extracellular N-terminal region and cytoplasmic C-terminal region (UniProt P21554 topology). Interpret cytoplasmic colour alongside cell-border staining; tissue IHC does not resolve which receptor surface carries the signal. |
| Antibody validation | HPA069945 has Enhanced IHC validation; HPA042256 has Supported ICC validation, with no IHC status supplied for that antibody (HPA antibodies). Use the validation for the application actually being interpreted; these entries do not establish equivalent performance. |
| Tissue and cell identity | HPA reports High staining at bronchial cilia tips, in placental cytotrophoblasts and testicular Sertoli cells, as well as in adipocytes and anterior pituitary cells (HPA tissue IHC). Identify the named cells or structures before using a tissue as a reference. |
| Lower-abundance variants | UniProt lists 3 isoforms and reports isoforms 2 and 3 at much lower levels than isoform 1 (UniProt P21554 isoforms/tissue specificity). Without an epitope map, the supplied evidence cannot show which isoforms an antibody detects. |
| Can ICC/IF show the same localisation? | HPA reports mainly plasma-membrane localisation in ICC/IF, with actin-filament localisation marked uncertain (HPA subcellular ICC-IF). This supports a membrane expectation but does not establish an IHC tissue pattern or an IF/ICC procedure. |
| Fixation sensitivity | Target-specific effects of fixation on CNR1 staining are unreported in the supplied UniProt and HPA records. Record the specimen preparation when comparing sections; do not attribute a changed result to CNR1 epitope masking without separate evidence. |
| Situation | Likely cause | Next action |
|---|---|---|
| Positive-reference adipocytes remain blank (HPA: High in adipocytes). | Possible run or detection failure; the supplied sources do not identify a CNR1-specific cause. | Check section integrity, antibody application and detection reagents with an appropriate run control; review the catalog antibody's IHC-P instructions before adjusting conditions. |
| Brown signal appears broadly in no-primary sections. | Background from the detection system or endogenous tissue activity is possible (general chromogenic IHC practice). | Use the no-primary section to localise the background, then check blocking and the detection controls appropriate to the chromogen system (general chromogenic IHC practice). |
| Signal is mainly nuclear. | This is discordant with membrane-associated CNR1 and the HPA tissue pattern (UniProt P21554 localisation; HPA tissue IHC). | Compare cell borders and cytoplasm in a known-positive section; inspect no-primary staining and antibody specificity before scoring nuclei as positive. |
| An HPA-negative cell population stains strongly. | Cross-reactivity or detection background is possible; HPA negative calls are cell-specific (HPA tissue IHC). | Confirm the cell identity, compare a matched positive tissue and no-primary control, and report the discrepancy rather than extending HPA's negative call to the whole organ. |
| Caudate neuronal signal looks weaker than adipocyte staining. | HPA reports Medium in caudate neuronal cells and High in adipocytes (HPA tissue IHC). | Score each cell population against its own expected level and morphology; preserve comparable imaging and detection settings when comparing sections. |
| ICC/IF shows filament-like signal alongside the cell membrane. | HPA lists actin-filament localisation as uncertain, while plasma-membrane localisation is supported (HPA subcellular ICC-IF). | Treat the filament-like component as unresolved, assess controls and membrane localisation, and consult the separate IF/ICC guide for application-specific setup. |
Experiment evidence
IHC & IF images showing CNR1 staining
A01291-1 · IHCIHC analysis of Cannabinoid Receptor I using anti-Cannabinoid Receptor I antibody (A01291-1). Cannabinoid Receptor I was detected in paraffi
A01291-1 · IHCIHC analysis of Cannabinoid Receptor I using anti-Cannabinoid Receptor I antibody (A01291-1). Cannabinoid Receptor I was detected in paraffi
HPA · Pituitary glandHuman Protein Atlas IHC, Pituitary gland. Source: https://www.proteinatlas.org/ENSG00000118432-CNR1/tissue/pituitary+gland#imid_1371
HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000118432-CNR1/tissue/cerebral+cortex#imid_20622315
HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000118432-CNR1/tissue/colon#imid_20622233
HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000118432-CNR1/tissue/liver#imid_20622250
HPA · ICC-IF AF22Human Protein Atlas immunofluorescence, AF22, antibody HPA042256; green = CNR1, blue = nucleus, red = microtubules.
HPA · ICC-IF AF22Human Protein Atlas immunofluorescence, AF22, antibody HPA042256; green = CNR1, blue = nucleus, red = microtubules.
← swipe / scroll for more images →
Real IHC / IF data behind the staining-pattern expectations in this section.
Sample controls for CNR1 IHC & IF
🧪Run bronchus first and look for staining at the tips of cilia in ciliated cells (HPA: High in ciliated cells, tip of cilia). Use heart muscle as the negative tissue; cardiomyocytes are listed as not detected (HPA: Not detected in cardiomyocytes). On the positive slide, adjacent surfaces without cilia provide an internal check for the ciliary-tip pattern, but their lack of that pattern does not establish that those cells are CNR1-negative (HPA: High at ciliated-cell ciliary tips).
Positive control tissue: Adipose tissue (Adipocytes, HPA High)
Negative control tissue: Adrenal gland (HPA Not detected)
ICC-IF cell lines (HPA subcellular resource): HPA ICC-IF images show CNR1 in AF22, ASC52telo, HeLa, with annotated localisation: Plasma membrane (supported) (HPA subcellular).
Technical controls: Include a no-primary, secondary-only control and a rabbit isotype control matched to the primary antibody’s immunoglobulin class and concentration (caption: rabbit primary antibody; standard IHC practice). A matched CNR1-knockout specimen provides a biological negative control; quench endogenous peroxidase for DAB detection and assess staining from the biotin-based detection system on bronchus sections (caption: biotinylated secondary, SABC and DAB; standard IHC practice).
⚠️Feasibility: No target-specific fixation window or fixation effect is reported, and the selected A01291-1 paraffin-section caption does not state its fixative (caption: fixative not stated). The caption uses citrate retrieval at pH 6 for 20 minutes, but does not establish that retrieval is required for bronchus or that frozen sections or IF/ICC are easier (caption: citrate retrieval; HPA: bronchus tissue staining). In bronchus, distinguish ciliary-tip signal from staining over adjacent surfaces and background from the biotin-based DAB system (HPA: High at ciliated-cell ciliary tips; caption: SABC and DAB).
HPA tissue IHC evidence for CNR1
Comprehensive Human Protein Atlas IHC scoring per tissue (reliability: Enhanced — Medium consistency between antibody staining and RNA expression data. Antibody staining in cells/structures not annotated, view images.). Rows are taken directly from the HPA tissue chart — click any row's HPA link to view the source.
Positive expression · recommended positive controls
| Tissue | Cell type | Level | Evidence | Source |
|---|---|---|---|---|
| Adipose tissue | Adipocytes | High | Protein (IHC) | HPA → |
| Breast | Adipocytes | High | Protein (IHC) | HPA → |
| Bronchus | Ciliated cells (tip of cilia) | High | Protein (IHC) | HPA → |
| Pituitary gland | Cells in anterior | High | Protein (IHC) | HPA → |
| Placenta | Cytotrophoblasts | High | Protein (IHC) | HPA → |
Undetected expression · recommended negative controls
| Tissue | Cell type | Level | Evidence | Source |
|---|---|---|---|---|
| Adrenal gland | Glandular cells | Not detected | Protein (IHC) | HPA → |
| Cervix | Glandular cells | Not detected | Protein (IHC) | HPA → |
| Esophagus | Squamous epithelial cells | Not detected | Protein (IHC) | HPA → |
| Heart muscle | Cardiomyocytes | Not detected | Protein (IHC) | HPA → |
| Hippocampus | Glial cells | Not detected | Protein (IHC) | HPA → |
Section 3
Advanced CNR1 IHC Tips
Troubleshoot CNR1 staining in paraffin sections by checking retrieval, cell type, subcellular pattern, and controls before interpreting DAB signal.
What retrieval should I start with for CNR1 in paraffin sections?
Start with heat-mediated retrieval in citrate buffer at pH 6 for 20 minutes (datasheet A01291-1). The catalog antibody produced staining in a paraffin-embedded mouse small intestine section after that treatment, followed by 1 μg/ml primary antibody overnight at 4°C (datasheet A01291-1). If staining is weak, check heating consistency, section adhesion, and primary antibody performance before changing retrieval conditions (standard IHC practice). Compare any adjusted retrieval with the documented condition on matched sections, since CNR1 membrane staining and tissue architecture both matter when judging improvement (UniProt P21554 localisation; standard IHC practice).
Could fixation explain weak or patchy CNR1 staining?
The selected tissue caption describes a paraffin-embedded section but does not state its fixative, so target-specific fixation sensitivity is unknown (datasheet A01291-1). Record the fixative and processing history for every case, then compare weak and strong areas with morphology and section integrity on adjacent sections (standard IHC practice). Keep retrieval at citrate pH 6 for 20 minutes while investigating processing differences, because that is the documented starting condition for this antibody (datasheet A01291-1). Avoid assigning a fixation effect from HPA staining patterns or CNR1 topology alone; neither establishes how this antibody's epitope survives fixation (HPA tissue IHC; UniProt P21554 topology).
Where should convincing CNR1 signal appear in a tissue section?
Look for a membranous component: CNR1 is annotated at the cell membrane, membrane rafts, axons, and presynapses (UniProt P21554 localisation). HPA reports cytoplasmic and membranous tissue staining, with abundant signal in adipocytes, pituitary gland, and the CNS, so a mixed pattern needs cell-level assessment (HPA tissue IHC). Its supported plasma membrane location provides a useful reference, while the reported actin filament location is uncertain (HPA subcellular). Examine whether DAB outlines plausible cells or processes in intact tissue; diffuse deposit across unrelated structures should prompt review of morphology and controls before scoring (standard IHC practice).
Can this stain distinguish CNR1 isoforms or membrane-facing epitopes?
Do not assign isoform identity from a positive DAB stain unless the antibody's immunogen or mapped epitope establishes which variants it recognizes (standard IHC practice). CNR1 has 3 annotated isoforms, and isoforms 2 and 3 are expressed at much lower levels than isoform 1 (UniProt P21554 isoforms; UniProt P21554 tissue specificity). The canonical receptor spans the membrane 7 times, with an extracellular N-terminal region and a cytoplasmic C-terminal region (UniProt P21554 topology). Check epitope documentation before interpreting retrieval sensitivity or apparent surface staining, and report unresolved isoform coverage as an assay limitation (standard IHC practice).
How should I plan a complementary CNR1 immunofluorescence check?
For a complementary IF experiment, pair CNR1 with a marker identifying the expected cell population and inspect whether signal follows the relevant cell boundaries or processes (UniProt P21554 localisation; standard IF practice). Choose fluorophores after checking tissue autofluorescence and include single-stain controls so bleed-through or native fluorescence is not mistaken for CNR1 (standard IF practice). Set permeabilisation according to the antibody's mapped epitope: a cytoplasmic C-terminal epitope needs access across the membrane, whereas an accessible extracellular epitope may require less disruption (UniProt P21554 topology; standard IF practice). The cited paraffin-section DAB workflow supplies no IF fixation or staining settings, so establish those conditions within the IF assay (datasheet A01291-1).
How can I reduce diffuse brown staining without losing CNR1 signal?
First compare the tissue with a no-primary control, then inspect whether brown deposit follows intact cells or appears across damaged areas and section edges (standard IHC practice). The documented workflow used 10% goat serum block, 1 μg/ml primary antibody overnight at 4°C, and a biotinylated secondary before DAB development (datasheet A01291-1). In a peroxidase-based workflow, verify the endogenous peroxidase block and evaluate secondary-only or detection controls when background persists (standard IHC practice). Change one variable at a time and retain a plausible membrane-associated pattern as the criterion for improvement (UniProt P21554 localisation; standard IHC practice).
What should I measure when comparing CNR1 staining across sections? ⚠ ANSWER MARKED FOR VERIFICATION
Define the cell population and tissue compartment before scoring, because CNR1 staining varies across cell types and can be membranous or cytoplasmic (HPA tissue IHC). For cellular staining, report an H-score or percentage of positive cells using a fixed positivity threshold; for punctate processes, consider stained area or density per mm² (standard IHC practice). Normalize each measure to the relevant intact tissue area or number of evaluable target cells, and exclude folds and damaged regions consistently (standard IHC practice). Use matched retrieval, primary concentration, detection, and imaging settings; document the catalog condition of 1 μg/ml primary antibody when applicable (datasheet A01291-1; standard IHC practice).
When is a CNR1-positive DAB pattern credible rather than artefactual?
A credible result fits intact cell morphology and an expected membrane-associated or process-associated distribution, with cytoplasmic staining interpreted in its tissue context (UniProt P21554 localisation; HPA tissue IHC). Compare the claimed positive cell type with reported patterns, such as high staining in adipocytes and anterior pituitary cells and absent staining in cardiomyocytes (HPA tissue IHC). Treat signal confined to section edges, necrotic areas, or the no-primary control as suspect, and check endogenous enzyme activity in the detection workflow (standard IHC practice). HPA rates tissue staining as Enhanced but reports only medium agreement with RNA expression, so confirm consequential cell-specific claims with independent evidence (HPA tissue IHC).
Boster reagents
Best CNR1 / Cannabinoid receptor 1 IHC Antibodies
The catalog antibody has IHC images from paraffin sections of mouse and rat small intestine (image captions: A01291-1); human reactivity and ICC use are listed, but no IF image is supplied (catalog: A01291-1).
Real IHC data
Anti-Cannabinoid Receptor I/CNR1 Antibody ®
Cat # A01291-1
A01291-1 will render with its mouse small intestine paraffin-section IHC figure (image caption: A01291-1). Its second IHC caption describes rat small intestine paraffin sections; the catalog lists human, mouse, and rat reactivity and ICC use, with no IF image (catalog: A01291-1).
Which to pick: Choose A01291-1 for paraffin-section tissue IHC: its captions document mouse and rat small intestine staining, while the fixative is unreported (image captions: A01291-1). For IF/ICC, A01291-1 lists ICC use but supplies no IF image or IF-specific validation (catalog: A01291-1). For cross-species work, A01291-1 lists human, mouse, and rat reactivity; the supplied IHC images document mouse and rat only (catalog and image captions: A01291-1).
Each figure is that product's own IHC / IF validation image from its datasheet.
References
- UniProt Consortium. UniProt entry P21554 (CNR1_HUMAN, Cannabinoid receptor 1).
- Human Protein Atlas. CNR1 tissue IHC expression (reliability: Enhanced).
- Human Protein Atlas. CNR1 subcellular location (ICC-IF): Mainly localized to the plasma membrane. In addition localized to the actin filaments..
- Human Protein Atlas. CNR1 antibody validation summary (2 antibodies).
- Altered Endocannabinoid Signaling in Placentas from SARS-CoV-2-Infected Pregnancies. Diagnostics (Basel, Switzerland) 2026 — PMC12984115.
- Role of cannabinoid receptor 1 in human adipose tissue for lipolysis regulation and insulin resistance. Endocrine 2017 — PMC5316391.
- Molecular annotation of integrative feeding neural circuits. Cell metabolism 2011 — PMC3286830.
- Possible Association of Nucleobindin-1 Protein with Depressive Disorder in Patients with HIV Infection. Brain sciences 2022 — PMC9496684.
- PubMed PMID:2263478 — UniProt-cited evidence.
- PubMed PMID:1718258 — UniProt-cited evidence.
- PubMed PMID:7876112 — UniProt-cited evidence.
Immunohistochemistry protocol sheet for CNR1 (Cannabinoid receptor 1). Expected localisation Cytoplasmic and membranous tissue staining (HPA tissue IHC). Antigen retrieval: Citrate pH 6 HIER, heat-mediated (datasheet A01291-1). Validated IHC antibody: A01291-1 at 0.5-1μg/ml (the product's own IHC validation image is shown). Controls (HPA): positive Adipose tissue (Adipocytes); negative Adrenal gland. IHC-P workflow on paraffin sections; fixative unspecified. Protocol steps: 1. Sample: Paraffin-embedded mouse small intestine tissue; fixative not specified (datasheet A01291-1); 2. Fixation: Image fixative and duration unreported (datasheet A01291-1); verify before use.; 3. Sectioning: 4–5 µm sections on charged slides (standard); 4. Deparaffinisation: Xylene, graded ethanol series to water (standard); 5. Antigen retrieval: Heat retrieval: Citrate pH 6 , 20 min (datasheet A01291-1); 6. Peroxidase block: 3% H2O2, 10 min , room temperature (standard); 7. Blocking: 10% goat serum (datasheet A01291-1); 8. Primary antibody: Rabbit anti-CNR1, 0.5-1μg/ml (datasheet A01291-1); 9. Primary incubation: Overnight at 4 °C (datasheet A01291-1). Watch for: Fixation: Keep fixation consistent across paraffin sections (standard IHC practice; not target-specific); Caveat: Antibody staining and RNA show medium consistency (HPA tissue IHC); Isoform / epitope: 3 isoforms; check epitope against the extracellular and cytoplasmic map (UniProt); Regulation: Isoforms 2 and 3 have much lower expression than isoform 1 (UniProt). Evidence: UniProt P21554, HPA tissue IHC · Enhanced, HPA ICC-IF · Mainly localized to the plasma membrane. In addition localized to…, Datasheet A01291-1, PMC12984115, PMC9496684. QR code links to https://www.bosterbio.com/bosterbio-gene-info-cards/CNR1/immunohistochemistry-ihc-guide.