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CCK Octapeptide (Sulfated), also known as CCK-8 (Sulfated), is the biologically active C-terminal octapeptide of cholecystokinin (CCK), a peptide hormone and neurotransmitter widely distributed throughout the gastrointestinal tract and central nervous system. Sulfation of the tyrosine residue is essential for high-affinity activation of the CCK1 (CCK-A) receptor and is responsible for many of the physiological actions associated with endogenous CCK.
Because the C-terminal octapeptide contains the complete receptor-binding pharmacophore of native CCK, sulfated CCK-8 has become the most commonly used experimental agonist for investigating CCK receptor biology, gastrointestinal physiology, satiety signaling, pancreatic secretion, gallbladder contraction, vagal afferent signaling, and neuroendocrine regulation.
Scientific Background
Cholecystokinin is synthesized as a larger precursor protein (proCCK) and processed into several biologically active peptides. Among these, sulfated CCK-8 is the predominant active form in both the gastrointestinal tract and central nervous system. Following food intake, endogenous CCK is released from intestinal I cells where it regulates digestive enzyme secretion, gallbladder contraction, gastric emptying, and communication between the gut and the brain.
In the brain, CCK functions as an important neuropeptide involved in appetite regulation, anxiety, learning, memory, pain processing, and neurotransmitter modulation. These diverse physiological functions have made sulfated CCK-8 one of the most extensively studied neuropeptides in biomedical research.
Mechanism of Action
CCK-8 (Sulfated) activates both CCK receptor subtypes, although sulfation is particularly important for high-affinity binding to the CCK1 (CCK-A) receptor. Receptor activation stimulates G-protein-mediated phospholipase C signaling, intracellular calcium mobilization, protein kinase activation, and secretion of digestive enzymes and gastrointestinal hormones.
- Activation of CCK1 (CCK-A) receptors
- Activation of CCK2 (CCK-B) receptors
- Intracellular calcium signaling
- PLC/IP3/DAG pathway activation
- Pancreatic enzyme secretion
- Gallbladder contraction
- Vagal afferent activation
Applications in Gastrointestinal Research
- Pancreatic secretion studies
- Gallbladder physiology
- Gastric emptying research
- Digestive hormone signaling
- Gut-brain communication
- Intestinal motility investigations
CCK-8 has become a standard agonist for studies examining digestive physiology because it closely reproduces endogenous CCK signaling after food ingestion.
Satiety and Obesity Research
One of the best-known physiological actions of CCK-8 is the regulation of meal size and satiety. Peripheral administration of sulfated CCK-8 activates vagal afferent neurons that transmit satiety signals from the gastrointestinal tract to the brainstem and hypothalamus, contributing to meal termination and regulation of food intake. These properties have made CCK receptor signaling an important area of obesity and metabolic disease research.
Neuroscience Research
CCK is one of the most abundant neuropeptides in the mammalian brain. Sulfated CCK-8 has been extensively used to investigate neurotransmission, anxiety-related behaviors, learning and memory, nociception, and interactions with dopaminergic, serotonergic, and opioid signaling pathways.
- Anxiety models
- Learning and memory studies
- Pain modulation
- Neuropeptide signaling
- Vagal-brain communication
- Neuroendocrine regulation
Inflammation and Pancreatitis Research
CCK-8 has also been employed in models of pancreatic physiology and pancreatitis, where investigators study digestive enzyme secretion, inflammatory signaling, and pancreatic injury. Additional studies have explored the influence of CCK receptor activation on immune responses and cytokine regulation.
Advantages of Sulfated CCK-8
- Physiologically active endogenous CCK fragment
- High affinity for CCK1 receptors
- Extensively characterized pharmacology
- Widely used reference agonist for CCK receptor studies
- Suitable for gastrointestinal and neuroscience research
- Useful for receptor pharmacology and drug discovery
Research Applications
- CCK receptor pharmacology
- Digestive physiology
- Pancreatic secretion
- Gallbladder contraction
- Satiety signaling
- Obesity research
- Gut-brain axis studies
- Neuroendocrine biology
- Pain and anxiety research
- Drug discovery targeting CCK receptors
Selected References
Rehfeld JF. Cholecystokinin—from local gut hormone to ubiquitous messenger in the nervous system and gastrointestinal tract.
Ondetti MA, Pluscec J, Sabo EF, Sheehan JT, Williams N. Chemical synthesis of CCK octapeptide and structure-activity investigations.
Additional studies have extensively characterized sulfated CCK-8 in gastrointestinal physiology, receptor pharmacology, satiety signaling, pancreatitis, and neuroscience research.
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