CCK-A (CCKAR) Neurons
<table class="infobox infobox-cell">
<tr>
<th class="infobox-header" colspan="2">CCK-A (CCKAR) Neurons</th>
</tr>
<tr>
<td class="label">Taxonomy</td>
<td>ID</td>
</tr>
<tr>
<td class="label">Cell Ontology (CL)</td>
<td>[CL:0002277](https://www.ebi.ac.uk/ols4/ontologies/cl/classes/http%253A%252F%252Fpurl.obolibrary.org%252Fobo%252FCL_0002277)</td>
</tr>
<tr>
<td class="label">Database</td>
<td>ID</td>
</tr>
<tr>
<td class="label">Cell Ontology</td>
<td>[CL:0002277](https://www.ebi.ac.uk/ols4/ontologies/cl/classes/http%253A%252F%252Fpurl.obolibrary.org%252Fobo%252FCL_0002277)</td>
</tr>
<tr>
<td class="label">Brain Region</td>
<td>Expression Level</td>
</tr>
<tr>
<td class="label">Cortex</td>
<td>Moderate</td>
</tr>
<tr>
<td class="label">Hippocampus</td>
<td>High</td>
</tr>
<tr>
<td class="label">Amygdala</td>
<td>High</td>
</tr>
<tr>
<td class="label">Hypothalamus</td>
<td>Moderate</td>
</tr>
<tr>
<td class="label">Brainstem</td>
<td>Variable</td>
</tr>
</table>
Introduction
Cck A (Cckar) Neurons is an important cell type in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.
Overview
...CCK-A (CCKAR) Neurons
<table class="infobox infobox-cell">
<tr>
<th class="infobox-header" colspan="2">CCK-A (CCKAR) Neurons</th>
</tr>
<tr>
<td class="label">Taxonomy</td>
<td>ID</td>
</tr>
<tr>
<td class="label">Cell Ontology (CL)</td>
<td>[CL:0002277](https://www.ebi.ac.uk/ols4/ontologies/cl/classes/http%253A%252F%252Fpurl.obolibrary.org%252Fobo%252FCL_0002277)</td>
</tr>
<tr>
<td class="label">Database</td>
<td>ID</td>
</tr>
<tr>
<td class="label">Cell Ontology</td>
<td>[CL:0002277](https://www.ebi.ac.uk/ols4/ontologies/cl/classes/http%253A%252F%252Fpurl.obolibrary.org%252Fobo%252FCL_0002277)</td>
</tr>
<tr>
<td class="label">Brain Region</td>
<td>Expression Level</td>
</tr>
<tr>
<td class="label">Cortex</td>
<td>Moderate</td>
</tr>
<tr>
<td class="label">Hippocampus</td>
<td>High</td>
</tr>
<tr>
<td class="label">Amygdala</td>
<td>High</td>
</tr>
<tr>
<td class="label">Hypothalamus</td>
<td>Moderate</td>
</tr>
<tr>
<td class="label">Brainstem</td>
<td>Variable</td>
</tr>
</table>
Introduction
Cck A (Cckar) Neurons is an important cell type in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.
Overview
Neurons expressing the cholecystokinin A receptor (CCKAR) represent a significant population in both the peripheral and central nervous systems. CCKAR, also known as CCK-A receptor, is a G-protein coupled receptor that binds cholecystokinin (CCK) peptides with high affinity [@dufresne2006]. These neurons play crucial roles in anxiety regulation, memory formation, satiety signaling, and pancreatic function. CCKAR is distinct from the CCK-B receptor (CCKBR) in its distribution and function, with CCKAR primarily expressed in peripheral tissues and select brain regions.
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Multi-Taxonomy Classification
Taxonomy Database Cross-References
External Database Links
- [Cell Ontology (CL:0002277)](https://www.ebi.ac.uk/ols4/ontologies/cl/classes/http%253A%252F%252Fpurl.obolibrary.org%252Fobo%252FCL_0002277)
- [OBO Foundry (CL:0002277)](http://purl.obolibrary.org/obo/CL_0002277)
- [Allen Brain Cell Atlas](https://portal.brain-map.org/atlases-and-data/bkp/abc-atlas)
- [CellxGene Census](https://cellxgene.cziscience.com/)
- [Human Cell Atlas](https://www.humancellatlas.org/)
Taxonomy & Classification
External Database Links
- [Cell Ontology (CL:0002277)](https://www.ebi.ac.uk/ols4/ontologies/cl/classes/http%253A%252F%252Fpurl.obolibrary.org%252Fobo%252FCL_0002277)
- [OBO Foundry (CL:0002277)](http://purl.obolibrary.org/obo/CL_0002277)
- [Allen Brain Cell Atlas](https://portal.brain-map.org/atlases-and-data/bkp/abc-atlas)
- [CellxGene Census](https://cellxgene.cziscience.com/)
Molecular Biology of CCKAR
Gene and Protein Structure
The CCKAR gene is located on chromosome 4p15.2 in humans and encodes a 406-amino acid G-protein coupled receptor [@cckar]. The receptor protein contains:
- N-terminal extracellular domain: Binds CCK peptides
- Seven transmembrane domains: Characteristic of GPCRs
- C-terminal intracellular domain: Couples to G proteins and initiates signaling
Ligands
CCKAR binds multiple forms of cholecystokinin:
- CCK-8: Octapeptide, highest affinity for CCKAR
- CCK-5: Pentapeptide variant
- CCK-4: Tetrapeptide, primarily CCKBR ligand
- Gastrin: Alternate ligand with lower affinity
Signaling Pathways
CCKAR activates multiple intracellular signaling cascades:
Phospholipase C (PLC) pathway: Increases IP3 and DAG, leading to calcium release
MAPK pathway: Regulates cell proliferation and differentiation
PI3K/Akt pathway: Involved in survival and growth
ERK1/2 activation: Mediates behavioral effectsDistribution in the Nervous System
Central Nervous System
CCKAR-expressing neurons are found in several brain regions:
Peripheral Nervous System
CCKAR is highly expressed in:
- Pancreas: Pancreatic acinar cells
- Gastrointestinal tract: Enteric neurons
- Vagus nerve: Afferent signaling
Function in Normal Physiology
Anxiety and Emotion Regulation
CCKAR neurons in the amygdala and hippocampus play a key role in anxiety:
- CCK acts as an anxiogenic peptide in the brain
- CCKAR activation produces anxiety-like behaviors in animal models
- CCKAR antagonists have anxiolytic properties [@bower2018]
- The CCK system interacts with GABAergic signaling
Memory and Cognition
CCKAR in the cortex and hippocampus modulates memory processes:
- CCK enhances memory consolidation
- CCKAR activation improves spatial memory in some studies
- Interaction with NMDA receptors affects synaptic plasticity
- May play a role in age-related cognitive decline
Satiety and Feeding
In the hypothalamus, CCKAR neurons regulate appetite:
- CCK is released from the gut during meals
- CCKAR activation signals satiety to the brain
- CCKAR antagonists can increase food intake
- Important for meal termination
Pancreatic Function
In the pancreas, CCKAR regulates digestive enzyme secretion:
- CCK stimulates pancreatic acinar cell secretion
- Important for fat digestion
- Dysregulation may contribute to pancreatic disorders
Role in Neurodegenerative Diseases
Alzheimer's Disease
CCKAR dysfunction is increasingly recognized in Alzheimer's disease:
CCK System Changes:
- Altered CCK levels in AD patients
- Reduced CCKAR expression in the hippocampus
- May contribute to memory impairment
Relationship with Amyloid:
- CCK neurons may be vulnerable to amyloid pathology
- Amyloid may disrupt CCK signaling
- Therapeutic targeting is being explored [@meyerlindenberg1997]
Therapeutic Potential:
- CCKAR agonists may improve cognition
- CCK/CCKAR-based strategies under investigation
Parkinson's Disease
The CCK system may be affected in Parkinson's disease:
- Altered CCK levels in the substantia nigra
- May modulate dopaminergic neuron function
- Possible role in non-motor symptoms
Anxiety Disorders
Given CCKAR's role in anxiety:
- CCKAR polymorphisms associated with panic disorder
- CCKAR antagonists being developed as anxiolytics
- Potential for personalized medicine approaches
Therapeutic Targeting
CCKAR Agonists
Potential Applications:
- Cognitive enhancement
- Appetite regulation
- Pancreatic insufficiency treatment
CCKAR Antagonists
Clinical Use:
- Devazepide: Research compound, anxiolytic potential
- Lintitript: CCK antagonist investigated for anxiety
Development Status:
- Clinical trials for anxiety disorders
- Investigated for pancreatic disorders
- May have cognitive benefits
- Devazepide: Selective CCKAR antagonist
- A-71623: CCKAR agonist
- SR 27897: CCKAR antagonist
- CCK Gene - Cholecystokinin
- CCKBR Gene - CCK B receptor
- GABA Receptors
- NMDA Receptor
- Cortical Pyramidal Neurons
- Hippocampal CA1 Neurons
- Amygdala Neurons
- Hypothalamic Neurons
- [Alzheimer's Disease](/diseases/alzheimers-disease)
- [Parkinson's Disease](/diseases/parkinsons-disease)
- Anxiety Disorders
- [Synaptic Plasticity](/mechanisms/synaptic-dysfunction)
- Anxiety Mechanisms
- Appetite Regulation
Background
The study of Cck A (Cckar) Neurons has evolved significantly over the past decades. Research in this area has revealed important insights into the underlying mechanisms of neurodegeneration and continues to drive therapeutic development.
Historical context and key discoveries in this field have shaped our current understanding and will continue to guide future research directions.
External Links
- NCBI Gene: [CCKAR](https://www.ncbi.nlm.nih.gov/gene/886)
- UniProt: [CCKAR](https://www.uniprot.org/uniprot/P32297)
- Ensembl: [CCKAR](https://ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000163394)
- IUPHAR: [CCKAR receptor](https://www.guidetopharmacology.org/1408)
- PubMed: [CCKAR neurodegeneration research](https://pubmed.ncbi.nlm.nih.gov/?term=CCKAR+neurodegeneration)