Disease relevance of Methionine enkephalin

• Changes of hippocampal Met-enkephalin content after recurrent motor seizures [1].
• The endogenous opioid met-enkephalin induced monocyte chemotaxis in a pertussis toxin-sensitive manner [2].
• Inhibition of B16-BL6 melanoma growth in mice by methionine-enkephalin [3].
• Methionine-enkephalin deficiency in brains of patients with Parkinson's disease [4].
• Thus, protection of methionine-enkephalin from degradation may be a factor contributing to the elevated plasma levels of methionine-enkephalin found in cholestasis [5].

Psychiatry related information on Methionine enkephalin

• The intraventricular injection of D-alanine-methionine-enkephalinamide (D-Ala2-Met-enkephalinamide), a synthetic analog of Met-enkephalin that is resistant to enzymatic degradation, inhibits copulatory behavior in sexually vigorous male rats in doses which do not influence motor activity or feeding behavior [6].
• The pentapeptides methionine-enkephalin and leucine-enkephalin are both able to reduce experimentally induced amnesia in rats [7].
• Plasma methionine-enkephalin in PTSD [8].
• In conclusion, beta-endorphin, beta-lipotropin, and met-enkephalin concentrations during pregnancy are not affected by drug addiction, whereas in the newborn of drug addicted mothers concentrations of these compounds are markedly increased [9].
• This study was carried out to analyze the extracellular levels of Met-enkephalin-like material in the nucleus accumbens, a brain structure involved in the effects of opioids on motor activity and reward processes, using microdialysis in awake and freely moving rats, combined with a sensitive radioimmunoassay [10].

High impact information on Methionine enkephalin

• We report here that a structure related to CD10/NEP is expressed by M. edulis haemocytes and that abrogation of CD10/NEP enzymatic activity reduces the amount of Met-enkephalin required for haemocyte activation by five orders of magnitude [11].
• The human proenkephalin gene consists of four exons, of which the main exon (exon IV) contains all known biologically active peptides--six Met-enkephalin sequences and one Leu-enkephalin sequence [12].
• Proenkephalin contains four copies of the sequence of Met-enkephalin, a single copy of the sequence of Leu-enkephalin and one copy each of two extended Met-enkephalin sequences [13].
• Accordingly, we have investigated the effect of nicotinic receptor stimulation on Met-enkephalin peptide biosynthesis and expression of proenkephalin messenger RNA in primary cultures of bovine chromaffin cells [14].
• The nucleotide sequence of cloned cDNA for preproenkephalin from bovine adrenal medulla indicates that the precursor protein contains four copies of Met-enkephalin and one copy each of Leu-enkephalin, Met-enkephalin-Arg6-Phe7 and Met-enkephalin-Arg6-Gly7-Leu8, a previously undetected opioid peptide [15].

Chemical compound and disease context of Methionine enkephalin

• The antitumor effect of methionine-enkephalin [( Met]enkephalin) was demonstrated in C57BL/6J mice inoculated with B16-BL6 melanoma cells [3].
• Incubation of neuroblastoma X glioma hybrid cells for 12-97 hr with methionine-enkephalin results in an increase in adenylate cyclase activity [ATP pyrophosphate-lyase (cyclizing), EC 4.6.1.1] that is mediated by the opiate receptor [16].
• Rats received ten weekly injections of 7.4 mg/kg of body weight of azoxymethane and injections of Met-enkephalin (50 micrograms/kg of body weight), naloxone (2 mg/kg of body weight), or Met-enkephalin (50 micrograms/kg of body weight) plus naloxone (2 mg/kg of body weight) once every 2 days [17].
• Tetanus toxin additionally inhibits the release of aspartate, gamma-aminobutyric acid and met-enkephalin from the same preparation [18].
• Tetanus toxin and botulinum toxins type A and B inhibit glutamate, gamma-aminobutyric acid, aspartate, and met-enkephalin release from synaptosomes. Clues to the locus of action [18].

Biological context of Methionine enkephalin

• The corresponding amino acid sequence shows that the precursor is 267 amino acids long and contains six interspersed Met-enkephalin sequences and one Leu-enkephalin sequence [19].
• Accordingly, Met-enkephalin, morphine and codeine potentiate the inhibition of pinocytosis caused by Ca2+-binding agents and reverse the calcium blockade of pinocytosis mediated by caffeine [20].
• Met-enkephalin generated from plasma by peptidic hydrolysis showed naloxone-reversible bioactivity comparable to synthetic Met-enkephalin [21].
• Acupuncture relief of chronic pain syndrome correlates with increased plasma met-enkephalin concentrations [22].
• Our results indicate that met-enkephalin, which has no effect on the resting membrane potential or conductance in these cells, reversibly and specifically shortens their Ca++ action potentials, probably by decreasing the Ca++ conductance [23].

Anatomical context of Methionine enkephalin

• Met-enkephalin has been detected in several species in a variety of tissues including brain, spinal cord and gut using bioassays, opiate receptor assays and radioimmunoassays (RIA) [24].
• While attempting to locate the cell bodies of the enkephalin containing neurones present in hippocampus using KA injections, we found that a few days after intracerebral injections of KA a drastic increase in the Met-enkephalin (ME) content of hippocampus occurs [1].
• Using a highly specific RIA, we have now obtained evidence that Met-enkephalin-like material circulates in the plasma of normal subjects and may be secreted by the adrenal gland [24].
• In vitro release of Leu- and Met-enkephalin from the corpus striatum [25].
• Single injections of 120 micrograms of methionine-enkephalin were made into various midbrain and forebrain structures in the rat [26].

Associations of Methionine enkephalin with other chemical compounds

• Here, the fluorescent indicator, quin2-acetoxymethyl ester, was used to measure directly cytosolic-free calcium during contraction of isolated stomach muscle cells induced by the two neuropeptides cholecystokinin-octapeptide and Met-enkephalin as well as acetylcholine [27].
• Using isolated rabbit ileal mucosa, we found that leucine enkephalin, methionine enkephalin, and D Ala2-methionine enkephalin amide (D Ala2-Met E) decreased the short circuit current (Isc) and potential difference although the effect of D Ala2-Met E was more pronounced and prolonged [28].
• It is concluded that the Met-enkephalin derivative FK 33824 directly suppresses ACTH release from the pituitary without influencing adrenal synthesis of cortisol [29].
• Luminal met-enkephalin levels were determined by radioimmunoassay and confirmed by HPLC [30].
• The ultrastructural localization of four neuropeptides, substance P, vasoactive intestinal polypeptide, Met-enkephalin, and somatostatin, in the guinea pig colon was investigated using electron immunocytochemistry [31].

Gene context of Methionine enkephalin

• Met-enkephalin, as well as morphine, inhibited IL-8-induced chemotaxis of human neutrophils and macrophage inflammatory protein (MIP)-1alpha, regulated upon activation, normal T expressed and secreted (RANTES), and monocyte chemoattractant protein 1, but not MIP-1beta-induced chemotaxis of human monocytes [2].
• Myenteric neurons additionally received terminations positive for neuropeptide Y, methionine-enkephalin, and somatostatin [32].
• A proportion of the latter group costained with vasoactive intestinal peptide and met-enkephalin [33].
• The release of both ACTH and Met-enkephalin from these cells is stimulated by corticotropin releasing factor, a natural secretagogue for ACTH, indicating that the two classes of peptide share a related secretory pathway [34].
• Previous studies show that Met-enkephalin, an endogenous opioid, down-regulates chemotaxis of selected chemokine receptors via phosphorylation [35].

Analytical, diagnostic and therapeutic context of Methionine enkephalin

• This analgesia was highly dose dependent, of much greater magnitude, and about 30 times longer lasting than that produced by the naturally occurring peptide, methionine-enkephalin [36].
• Radioimmunoassays revealed the presence of beta-endorphin and methionine-enkephalin in these tumors [37].
• To determine whether monocytes or lymphocytes express met-enkephalin in vivo, lymphoid tissues were analyzed by immunohistochemistry [38].
• Plasma levels of the individual endogenous opioid, methionine-enkephalin, were determined using a sensitive radioimmunoassay, and the specificity of the assay was confirmed using high-performance liquid chromatography [5].
• However, successful electroacupuncture was associated with a rise in CSF met-enkephalin levels in all patients studied, although concentrations in blood did not alter [39].

References