Met-Enkephalin

Met-enkephalin, also known as opioid growth factor (OGF) or methionine enkephalin, is one of the two major types of enkephalins, which are naturally occurring peptides in the brain that function as endogenous opioid neurotransmitters. These peptides bind to opioid receptors in the body, particularly the delta-opioid receptors, to modulate pain, mood, and various physiological functions. Met-enkephalin has garnered interest for its potential therapeutic uses in pain management, immune modulation, and even cancer treatment. Its involvement in the body’s opioid system makes it a crucial player in regulating analgesia, immune responses, and cellular growth.

Category

Endogenous Opioid Peptide

Sequence

H-Tyr-Gly-Gly-Phe-Met-OH

Molecular Weight

Approximately 573.66 g/mol

Molecular Formula

C27H35N5O7S

Half Life

Less than two minutes

Most Common Uses

Met-enkephalin is integral to several physiological processes due to its role as an endogenous neurotransmitter and neuromodulator. It binds to opioid receptors in the brain and spinal cord to modulate pain perception, supporting the body’s natural mechanisms for pain relief, particularly during stress or injury, by reducing discomfort. The peptide also contributes to managing the body’s response to stress, as it is released in the central nervous system to regulate emotional and physiological reactions, fostering a sense of calm in challenging situations. Additionally, Met-enkephalin acts as a signaling molecule within the nervous system, facilitating neuron communication and influencing mood, behavior, and other neurological functions through its interaction with mu-opioid receptors.

Researchers study it to explore its potential in understanding conditions such as depression, anxiety, and addiction, given its impact on the brain’s reward system, making it a focal point for developing treatments for these disorders. Met-enkephalin is investigated for its role in immune function, as it is present in immune cells and tissues and may help modulate immune responses, particularly in inflammatory conditions. Although not used directly as a medication, it inspires the development of synthetic analogs for pain relief, aiming to replicate its pain-relieving effects while minimizing side effects compared to traditional opioids. Met-enkephalin’s wide-ranging roles underscore its significance in both physiological processes and medical research.

Mechanism of Action

Met-enkephalin exerts its effects primarily through interactions with opioid receptors in the central and peripheral nervous systems. Composed of the amino acid sequence Tyr-Gly-Gly-Phe-Met, this pentapeptide binds predominantly to mu-opioid receptors, with some affinity for delta-opioid receptors. Upon binding, it activates these G-protein-coupled receptors, initiating a cascade of intracellular signaling events. This activation inhibits adenylate cyclase, reducing cyclic AMP levels, which modulates neuronal excitability. Additionally, Met-enkephalin promotes the opening of potassium channels and inhibits calcium channels, leading to hyperpolarization of neurons and decreased neurotransmitter release.

These actions result in reduced pain perception, as the peptide dampens the transmission of pain signals in the spinal cord and brain. Beyond pain modulation, Met-enkephalin influences mood, stress responses, and reward pathways, contributing to its role in emotional regulation. Its effects are short-lived due to rapid degradation by enzymes such as enkephalinases, which cleave the peptide in extracellular spaces. This mechanism underpins Met-enkephalin’s role in natural pain relief, stress adaptation, and neurological signaling, making it a significant focus in neuroscientific research.

Structure and Pharmacology

Met-enkephalin consists of a five-amino-acid sequence: tyrosine-glycine-glycine-phenylalanine-methionine (H-Tyr-Gly-Gly-Phe-Met-OH). This compact structure, with a molecular weight of approximately 573.7 g/mol and a molecular formula of C27H35N5O7S, enables its role as a neurotransmitter and neuromodulator. The peptide’s tyrosine residue at the N-terminus facilitates binding to opioid receptors, while the methionine at the C-terminus distinguishes it from its counterpart, Leu-enkephalin. Its small size and specific amino acid arrangement allow precise interactions with receptor sites in the nervous system.

Pharmacologically, Met-enkephalin exerts its effects primarily through binding to mu-opioid receptors, with moderate affinity for delta-opioid receptors, in the brain, spinal cord, and peripheral tissues. This binding activates G-protein-coupled signaling pathways, inhibiting adenylate cyclase to reduce cyclic AMP levels, which modulates neuronal activity. The peptide also promotes potassium channel opening and inhibits calcium channels, hyperpolarizing neurons and reducing neurotransmitter release. These actions contribute to analgesia, mood regulation, and stress response modulation. Met-enkephalin’s short half-life results from rapid degradation by peptidases, such as enkephalinases, limiting its duration of action. Its pharmacological profile inspires research into synthetic analogs for pain management and neurological disorders, aiming to extend its therapeutic effects while minimizing side effects.

Dosages

Met-enkephalin is not administered as a pharmaceutical drug due to its rapid degradation in the body and short half-life. As a naturally occurring peptide produced in the brain and other tissues, it does not have standardized therapeutic dosages like synthetic medications. Instead, its physiological effects arise from endogenous release in response to stimuli such as pain or stress, with concentrations varying based on individual biological factors. Research exploring Met-enkephalin or its synthetic analogs for potential therapeutic use, such as pain management or neurological disorders, typically involves experimental settings rather than clinical dosing regimens.

In these studies, analogs designed to resist enzymatic breakdown may be administered in controlled amounts, often in microgram or milligram ranges, depending on the delivery method, such as intravenous or intrathecal injection. However, specific dosage guidelines for Met-enkephalin itself remain undefined in clinical practice, as its use is primarily investigational. Ongoing research aims to develop stable derivatives that mimic its effects, potentially leading to defined dosages for future therapeutic applications.

Warnings and Cautions

Met-enkephalin is not used as a clinical medication, so direct warnings and cautions apply primarily to its research and potential therapeutic analogs. As a naturally occurring peptide, it is produced in the body to modulate pain and stress responses, but its rapid degradation by enzymes like enkephalinases limits its practical use in medical settings. Researchers handling Met-enkephalin or its synthetic analogs in experimental studies should exercise caution due to its opioid-like effects, which may influence pain perception, mood, and neurological function through mu-opioid and delta-opioid receptor activation.

Excessive or uncontrolled administration of analogs in research could lead to unintended side effects, such as sedation, respiratory depression, or altered emotional states, similar to other opioids. People with a history of opioid sensitivity or substance use disorders may require special consideration in studies involving Met-enkephalin derivatives to avoid potential adverse reactions. Laboratory handling of this peptide demands strict adherence to safety protocols, as improper use or exposure could affect neurological or immune responses. Pregnant or breastfeeding women should avoid exposure to synthetic analogs in research settings, as their effects on fetal or infant development remain understudied. Any experimental use of Met-enkephalin-based compounds should occur under rigorous medical supervision to ensure safety and monitor for unexpected physiological impacts.

Research & Trials

Endogenous Opiates: 1996

Hepatoprotective Effects of Met-enkephalin in Mice

Sourcing

USA

LIMITLESS LIFE NOOTROPICS aka Biotech

Use Discount Code: EP20

SCANTIFIX

Use Discount Code: Exploringpeptides

Canada

BIOSLAB

Use Discount Code: EP10

Europe

DNLABResearch

Use Discount Code: EP15

Australia

LVLUPHEALTH

References

[1] Olson, G. A., Olson, R. D., & Kastin, A. J. (1997). Endogenous opiates: 1996. Peptides, 18(10), 1651–1688. https://doi.org/10.1016/S0196-9781(97)00264-7

[2] Martinić, R., Šošić, H., Turčić, P., Konjevoda, P., Fučić, A., Stojković, R., Aralica, G., Gabričević, M., Weitner, T., & Štambuk, N. (2014). Hepatoprotective Effects of Met-enkephalin on Acetaminophen-Induced Liver Lesions in Male CBA Mice. Molecules, 19(8), 11833-11845. https://doi.org/10.3390/molecules190811833

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