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CNR1 / Cannabinoid receptor 1 · IHC design guide
Design Immunohistochemistry for CNR1
Plan CNR1 paraffin IHC with the catalog antibody at 0.5–1 µg/mL (datasheet A01291-1). Use adipocytes as a positive reference and score cytoplasmic and membranous staining by cell type (HPA tissue IHC).
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 | High in adipocytes; cytoplasmic/membranous (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 sections (standard IHC practice; not target-specific); Matched tissue-IHC evidence does not establish the fixation claim. Validate the specimen-specific method before use. (selected-SKU IHC image A01291-1) | |
| Caveat | CNS staining varies by cell type; hippocampal glia are undetected (HPA tissue IHC) | |
| Regulation | Tissue dependent; brain enriched (UniProt) | |
| Isoform / epitope | 3 isoforms; check extracellular versus cytoplasmic epitope coverage (UniProt) |
Section 1
Recommended CNR1 IHC & IF Protocols
The catalog antibody’s IHC-P protocol is paired with published chromogenic IHC protocols for placental tissue 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 citrate pH 6 heat retrieval for the catalog antibody (datasheet A01291-1); the published protocols used EDTA pH 8 and high-pH retrieval, respectively (PMC12984115; PMC9496684).
Section 2
What Is the Expected CNR1 Staining Pattern?
CNR1 is a seven-transmembrane receptor associated with the cell membrane, axons and presynapses; UniProt also annotates the mitochondrial outer membrane (UniProt P21554 topology; UniProt P21554 subcellular). In tissue IHC, HPA reports cytoplasmic and membranous staining, including high staining in adipocytes and anterior pituitary cells (HPA tissue IHC). HPA rates the tissue pattern Enhanced while reporting medium consistency with RNA data (HPA tissue IHC).
| Membranous staining, with some cytoplasmic staining, in adipocytes or anterior pituitary cells. | This matches HPA's tissue pattern and its high staining levels in those cells (HPA tissue IHC). Score the named cell population and compartment together; intensity alone does not establish specificity, especially where the tissue contains several cell types (general IHC practice). |
| Predominantly nuclear staining, without the expected membranous or cytoplasmic pattern. | Treat this as a possible artefact: HPA describes cytoplasmic and membranous tissue staining, while UniProt annotates membrane-associated locations (HPA tissue IHC; UniProt P21554 subcellular). Review the control and antibody conditions before calling it CNR1 (general IHC practice). |
| Strong staining in glomerular cells, cardiomyocytes or esophageal squamous cells. | HPA reports CNR1 as not detected in these specific cell populations (HPA tissue IHC). Check for cross-reactivity or endogenous detection activity before accepting the signal (general IHC practice). A negative annotation for those cells does not classify every cell in the same organ. |
| Diffuse color across tissue and empty slide areas, obscuring cell boundaries. | This distribution is difficult to reconcile with HPA's named positive cell populations and membranous or cytoplasmic pattern (HPA tissue IHC). Evaluate nonspecific reagent binding, detection background and washing with suitable controls (general IHC practice). Do not score diffuse color as cellular positivity. |
| No staining in an adipocyte-rich area or anterior pituitary cells. | HPA reports high staining in adipocytes and anterior pituitary cells, so an absent result needs technical review (HPA tissue IHC). Confirm that the expected cells are present, then check the antibody, detection reagents and run controls (general IHC practice). |
💡Expected CNR1 appearanceCall a result positive when identifiable adipocytes or anterior pituitary cells show clear membranous and/or cytoplasmic staining at the high level reported by HPA; isolated nuclear color or diffuse background is suspect (HPA tissue IHC; general IHC practice).
| Compartment and epitope position | CNR1 has seven transmembrane segments and distinct extracellular and cytoplasmic regions (UniProt P21554 topology). Interpret staining against the antibody's stated epitope if available; the supplied record gives no epitope for a catalog antibody. HPA's tissue IHC pattern is both membranous and cytoplasmic (HPA tissue IHC). |
| Tissue and cell selection | HPA reports high staining in adipocytes, anterior pituitary cells, placental cytotrophoblasts and testicular Sertoli cells, but medium staining in caudate neuronal cells (HPA tissue IHC). Record the cell population examined; a whole-organ positive or negative label would hide these differences. |
| Isoform coverage | UniProt lists three CNR1 isoforms and reports much lower expression of isoforms 2 and 3 than isoform 1 (UniProt P21554). The supplied evidence does not identify an antibody epitope or establish which isoforms an IHC signal detects; avoid assigning an isoform from staining alone. |
| Strength of tissue evidence | HPA labels tissue IHC reliability Enhanced and notes medium consistency between staining and RNA expression (HPA tissue IHC). Its negative calls apply to specified cell populations, including hippocampal glial cells, rather than every cell in those tissues (HPA tissue IHC). |
| IF/ICC Q: What localisation is reported? | A: HPA reports plasma membrane as the supported main ICC-IF location and actin filaments as an uncertain additional location (HPA subcellular ICC-IF). This is an IF interpretation cue; it does not supply an IF protocol or replace the tissue IHC pattern. |
| Situation | Likely cause | Next action |
|---|---|---|
| Expected positive cells are unstained. | The sampled field may lack the named positive population (HPA tissue IHC), or the staining run may have failed (general IHC practice). | Locate identifiable adipocytes or anterior pituitary cells and compare them with a positive run control; then check antibody and detection steps (HPA tissue IHC; general IHC practice). |
| Signal is weak in a purported negative control. | The control may contain a different CNR1-staining cell population; HPA negative calls are cell-specific (HPA tissue IHC). | Score the annotated cells, such as cardiomyocytes in heart muscle, and document the exact population examined (HPA tissue IHC). |
| Color appears after omitting the primary antibody. | Primary-independent signal can arise from endogenous detection activity or other detection reagents (general IHC practice). | Review the detection-only control and use the blocking or detection controls appropriate to the chromogenic system (general IHC practice). |
| Color spreads across many cell types and the slide background. | Diffuse signal can reflect nonspecific binding or excess detection background (general IHC practice). | Compare with a primary-omission control, review blocking and washing, and reassess antibody concentration using the assay instructions (general IHC practice). |
| A predominantly nuclear pattern appears in otherwise positive tissue. | The pattern conflicts with HPA's membranous and cytoplasmic tissue description and UniProt's membrane-associated locations (HPA tissue IHC; UniProt P21554 subcellular). | Check whether the nuclear color persists in controls; withhold a specific CNR1 call until the expected cellular pattern is resolved (general IHC practice). |
| An antigen retrieval change gives a different result. | Retrieval conditions can alter IHC staining generally; CNR1-specific fixation or retrieval sensitivity is unreported in the supplied sources (general IHC practice). | Compare conditions on the same known-positive cell population with matched controls; do not infer a CNR1-specific fixation effect from this change alone (HPA tissue IHC; general IHC practice). |
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: ciliated cells should stain at the tips of their cilia (HPA: High in bronchial ciliated cells, tip of cilia). Use esophagus as the negative tissue (HPA: Not detected in esophageal squamous epithelial cells); on the bronchus slide, areas without ciliary tips should lack a comparable apical staining pattern.
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 no-primary (secondary-only), species- and class-matched rabbit IgG isotype, and CNR1-knockout tissue if available (caption: rabbit primary antibody; standard IHC practice). For bronchus, quench endogenous peroxidase and check for endogenous biotin background when using the reported SABC/DAB detection (caption: SABC/DAB; standard IHC practice).
⚠️Feasibility: A target-specific fixation window or fixation effect is unreported, and the selected A01291-1 paraffin-section caption does not state the fixative. The caption uses citrate retrieval at pH 6 for 20 minutes; whether staining depends on that retrieval is unreported (caption: citrate retrieval). The supplied evidence does not establish that frozen sections or IF are easier; in bronchus, distinguish cilia-tip staining from luminal mucus or DAB deposits (HPA: cilia-tip staining; standard IHC practice).
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 chromogenic IHC in paraffin sections by checking retrieval, staining controls, expected localisation, and scoring before interpreting regional differences.
Which retrieval condition should I try first for weak CNR1 staining?
Start with heat-mediated citrate buffer at pH 6 for 20 minutes on paraffin sections (datasheet A01291-1). The same caption uses 1 μg/mL primary antibody overnight at 4°C; hold that exposure constant when comparing retrieval conditions (datasheet A01291-1; standard IHC practice). If staining remains weak, compare shorter and longer heating intervals in citrate buffer on matched sections, assessing tissue morphology alongside signal (standard IHC practice). Include tissue with expected expression, such as adipocytes, and a primary-omission control before attributing stronger DAB staining to CNR1 (HPA: high in adipocytes; standard IHC practice).
Could fixation explain inconsistent CNR1 staining between paraffin sections?
CNR1-specific fixation sensitivity is unknown: no target-specific comparison is supplied, and the selected paraffin caption does not state a fixative (datasheet A01291-1). For new specimens, document the fixative, fixation duration, section age, and processing batch before comparing chromogenic signal (standard IHC practice). Keep these variables consistent, then evaluate matched sections using citrate buffer at pH 6 for 20 minutes and 1 μg/mL primary antibody (datasheet A01291-1; standard IHC practice). Include an expected positive population and a primary-omission control to help distinguish processing loss from nonspecific chromogen deposition (HPA: high in adipocytes; standard IHC practice).
Where should convincing CNR1 staining appear in tissue sections?
Expect chiefly membranous staining, with possible cytoplasmic staining in tissue; plasma membrane is the supported subcellular assignment (HPA tissue IHC; HPA subcellular). CNR1 is also annotated at membrane rafts, axons, presynapses, and mitochondrial outer membranes, so interpret puncta against anatomy and controls (UniProt P21554 localisation; standard IHC practice). Its 7 membrane-spanning segments place the canonical C terminus on the cytoplasmic side, while the mitochondrial C terminus has unusual topology (UniProt P21554 topology). Score staining within defined cells and compartments; review diffuse nuclear or section-edge DAB against morphology and primary-omission slides (standard IHC practice).
Can this stain distinguish CNR1 isoforms or reveal a masked epitope?
CNR1 has 3 reported isoforms, with isoforms 2 and 3 expressed much less than isoform 1 (UniProt P21554 isoforms; tissue specificity). An isoform-specific interpretation needs a mapped immunogen or epitope and sequence comparison; the supplied A01291-1 caption gives no epitope map (datasheet A01291-1; standard IHC practice). The receptor has 7 transmembrane segments, extracellular residues 1–116, and a cytoplasmic C-terminal region at 400–472, making epitope accessibility a processing concern (UniProt P21554 topology; standard IHC practice). Keep retrieval consistent and seek orthogonal validation before calling regional staining differences isoform-specific (standard IHC practice).
How can IF help assess the CNR1 pattern seen by IHC?
Multiplex CNR1 with a marker of the expected cell population, such as adipocytes, and assess spatial overlap within intact cells (HPA: high in adipocytes; standard IF practice). Choose fluorophores after checking tissue autofluorescence in the intended channels, and include unstained and secondary-only controls before assigning puncta to CNR1 (standard IF practice). For a cytoplasmic epitope, optimise mild permeabilisation; an extracellular epitope may be accessible without it, but the antibody epitope is unspecified here (UniProt P21554 topology; datasheet A01291-1; standard IF practice). Compare the result with supported plasma-membrane localisation, treating actin-filament localisation cautiously because that additional assignment is uncertain (HPA subcellular).
What should I check when CNR1 DAB staining is widespread?
Begin with the caption's 10% goat serum block and 1 μg/mL primary antibody overnight at 4°C (datasheet A01291-1). Run primary-omission and secondary-only controls, then adjust blocking, washing, and primary concentration one variable at a time (standard IHC practice). Because the reported workflow uses a biotinylated secondary and streptavidin-biotin complex, assess endogenous biotin and include a peroxidase block before DAB development (datasheet A01291-1; standard IHC practice). Compare with a population expected to lack signal, such as cardiomyocytes, and distrust uniform edge staining or pigment appearing in controls (HPA: cardiomyocytes not detected; standard IHC practice).
How should I quantify CNR1 staining across tissue sections? ⚠ ANSWER MARKED FOR VERIFICATION
Define the cell population and compartment before scoring, because CNR1 tissue staining can be membranous or cytoplasmic (HPA tissue IHC). For discrete cells, report percent positive and an H-score calculated from intensity 0–3 multiplied by the percentage of cells at each intensity (standard IHC practice). For axonal or presynaptic profiles, measure positive area or puncta density per mm² in anatomically matched regions rather than counting nuclei (UniProt P21554 localisation; standard IHC practice). Normalise to eligible cell number or analysed tissue area, apply one threshold across batches, and exclude folds, necrosis, and section edges (standard IHC practice).
How do I distinguish genuine CNR1 signal from artefact?
Staining is more credible when it follows membranous or presynaptic anatomy in an expected cell population and is absent from primary-omission controls (UniProt P21554 localisation; standard IHC practice). Adipocytes show high signal, whereas cardiomyocytes are not detected in the supplied tissue profile (HPA: high in adipocytes; HPA: cardiomyocytes not detected). Diffuse nuclear DAB, isolated section-edge signal, or staining confined to necrotic debris warrants review against morphology and controls (standard IHC practice). Check endogenous peroxidase and biotin contributions in this biotin-based DAB workflow, and compare patterns across matched sections before assigning biological meaning (datasheet A01291-1; standard IHC practice).
Boster reagents
Best CNR1 / Cannabinoid receptor 1 IHC Antibodies
A01291-1 is listed for IHC and ICC in human, mouse and rat; its IHC images show paraffin sections of mouse and rat small intestine (catalog applications/reactivity; IHC image captions).
Real IHC data
Anti-Cannabinoid Receptor I/CNR1 Antibody ®
Cat # A01291-1
A01291-1 has IHC images from paraffin sections of mouse and rat small intestine (A01291-1 IHC image captions). It lists human, mouse and rat reactivity and ICC as an application, but supplies no IF image (catalog reactivity/applications; IF image alts).
Which to pick: Choose A01291-1 for paraffin-section tissue IHC: its mouse and rat captions document citrate retrieval at pH 6 for 20 minutes and 1 μg/ml primary antibody; the fixative is unreported (A01291-1 IHC image captions). For IF/ICC, A01291-1 lists ICC at 0.5–1 μg/ml, but supplies no IF image; clonality is unreported (catalog applications/dilution; IF image alts; clone field). For cross-species work, A01291-1 lists human, mouse and rat reactivity, with tissue IHC images for mouse and rat (catalog reactivity; A01291-1 IHC image captions).
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 sections (standard IHC practice; not target-specific); Matched tissue-IHC evidence does not establish the fixation claim. Validate the specimen-specific method before use. (selected-SKU IHC image A01291-1); Caveat: CNS staining varies by cell type; hippocampal glia are undetected (HPA tissue IHC); Isoform / epitope: 3 isoforms; check extracellular versus cytoplasmic epitope coverage (UniProt); Regulation: Tissue dependent; brain enriched (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.