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Pharmacology, Biochemistry, and Behavior Dec 1993The effects of SC injections of methionine-enkephalin (Met1-5-Enk) and its N-terminal and C-terminal fragments upon the duration of the dorsal immobility response (DIR)...
The effects of SC injections of methionine-enkephalin (Met1-5-Enk) and its N-terminal and C-terminal fragments upon the duration of the dorsal immobility response (DIR) over a 60-min time course were investigated. Experiment 1 analyzed the effects of various dosages (0.00-100.0 micrograms/kg) on DIR resulting in a potentiation of the duration in a dose-time course function. The effects of various fragments of Met1-5-Enk (10.0 micrograms/kg) from the N-terminal in Experiment 2 and from the C-terminal in Experiment 3 on the DIR resulted in the potentiation of the duration with the Met2-5-Enk and Met1-3-Enk fragments. All other fragments were not significant. The results were discussed in reference to the processing and metabolism of Met1-5-Enk.
Topics: Amino Acid Sequence; Animals; Dose-Response Relationship, Drug; Enkephalin, Methionine; Male; Molecular Sequence Data; Motor Activity; Rats; Time Factors
PubMed: 8309964
DOI: 10.1016/0091-3057(93)90210-k -
British Journal of Urology Jan 1987The influence of methionine-enkephalin and leucine-enkephalin on human detrusor and on pig detrusor, trigone, bladder neck and urethral smooth muscle was investigated in...
The influence of methionine-enkephalin and leucine-enkephalin on human detrusor and on pig detrusor, trigone, bladder neck and urethral smooth muscle was investigated in vitro. The enkephalins inhibited the smooth muscle contractility presynaptically. Methionine-enkephalin was about 40% more potent than leucine-enkephalin. Phentolamine-resistant contractions were less inhibited by the enkephalins than atropine-resistant contractions and contractions that were not blocked. The inhibitory nerve responses of the trigone, bladder neck and urethra were unaffected.
Topics: Animals; Depression, Chemical; Enkephalin, Leucine; Enkephalin, Methionine; Female; In Vitro Techniques; Muscle Contraction; Muscle, Smooth; Swine; Urinary Tract
PubMed: 3828685
DOI: 10.1111/j.1464-410x.1987.tb04574.x -
British Medical Journal Aug 1980
Topics: Asthma; D-Ala(2),MePhe(4),Met(0)-ol-enkephalin; Endorphins; Enkephalin, Methionine; Forced Expiratory Volume; Humans
PubMed: 7437133
DOI: 10.1136/bmj.281.6236.387-b -
Chemical Biology & Drug Design Dec 2016The Met-enkephalin, Tyr-Gly-Gly-Phe-Met, was synthesized by the solution-phase synthesis (SPS) methodology employing -OBzl group as carboxyls' protection, while the...
The Met-enkephalin, Tyr-Gly-Gly-Phe-Met, was synthesized by the solution-phase synthesis (SPS) methodology employing -OBzl group as carboxyls' protection, while the t-Boc groups were employed for the N-terminal α-amines' protection for the majority of the amino acids of the pentapeptide sequence. The l-methionine (l-Met) amino acid was used as PTSA.Met-OBzl obtained from the simultaneous protection of the α-amino, and carboxyl group with para-toluene sulfonic acid (PTSA) and as-OBzl ester, respectively in a C-terminal start of the 2 + 2 + 1 fragments condensation convergent synthetic approach. The protection strategy provided a short, single-step, simultaneous, orthogonal, nearly quantitative, robust, and stable process to carry through the protected l-methionine and l-phenylalanine coupling without any structural deformities during coupling and workups. The structurally confirmed final pentapeptide product was feasibly obtained in good yields through the current approach.
Topics: Benzenesulfonates; Enkephalin, Methionine; Methionine; Peptides
PubMed: 27434150
DOI: 10.1111/cbdd.12821 -
European Journal of Pharmacology Mar 1994We examined the effect of [Met5]enkephalin-Arg6-Phe7 (MEAP) on the capsaicin-induced cough reflex in mice. Intracerebroventricular administration of MEAP significantly...
We examined the effect of [Met5]enkephalin-Arg6-Phe7 (MEAP) on the capsaicin-induced cough reflex in mice. Intracerebroventricular administration of MEAP significantly decreased the number of coughs in a dose-dependent manner. The antitussive effect of MEAP was blocked by nor-binaltorphimine, a selective kappa-opioid receptor antagonist. However, beta-funaltrexamine, a mu-opioid receptor antagonist, had no effect on the antitussive effect of MEAP. On the other hand, the antinociceptive effect of MEAP, as determined in the tail-flick test, was blocked by both nor-binaltorphimine and beta-funaltrexamine. Naltrindole, a delta-opioid receptor antagonist, had no effect on either the antitussive effect or the antinociceptive effect of MEAP. These data suggest that MEAP exerts its antitussive effect in mice through the stimulation of kappa-opioid receptors, whereas the antinociceptive effect of MEAP is mediated through the simulation of both kappa- and mu-opioid receptors.
Topics: Animals; Antitussive Agents; Capsaicin; Cough; Dose-Response Relationship, Drug; Enkephalin, Methionine; Injections, Intraventricular; Male; Mice; Naltrexone; Narcotic Antagonists; Receptors, Opioid, kappa; Receptors, Opioid, mu
PubMed: 8200424
DOI: 10.1016/0014-2999(94)90205-4 -
American Journal of Orthodontics and... Jul 1987Public perception is that dentistry and pain go hand in hand; thus, pain and pain control are important considerations to the profession. Recent studies have attempted...
Public perception is that dentistry and pain go hand in hand; thus, pain and pain control are important considerations to the profession. Recent studies have attempted to discover the precise metabolic events involved in neural transmission of nociceptive information. One focus has been the study of peptidergic pathways, which purportedly inhibit the firing of pain-conducting fibers. The research described in this article defined the existence of one enkephalin, methionine enkephalin (ME), in an extract of human tooth pulp tissue and the effect of orthodontic force on that ME concentration. One set of patients who had premolars extracted for orthodontic purposes served as controls. Another set, also diagnosed for premolar extractions, had a coil spring attached between the left and right maxillary premolars to supply an orthodontic force for a period of time prior to extraction. High-performance liquid chromatography, radioimmunoassay, radioreceptor assay, and mass spectrometry were used in a series of experiments to isolate, identify, and quantify ME in the pulp tissues. Principal results were as follows: for the first time ME was detected in human tooth pulp, orthodontic force caused a significant decrease in ME concentrations in the group of experimental teeth compared with controls, and ME levels of the first spring-attached tooth that was removed from each patient had a statistically significant inverse log-linear relationship to the amount of applied force. These data indicate that orthodontic force mobilizes at least one neuropeptidergic pathway in the human tooth pulp.
Topics: Chromatography, High Pressure Liquid; Dental Pulp; Enkephalin, Methionine; Female; Humans; Male; Mass Spectrometry; Orthodontic Appliances; Radioimmunoassay; Radioligand Assay; Stress, Mechanical; Time Factors; Tooth Extraction
PubMed: 3474889
DOI: 10.1016/0889-5406(87)90290-3 -
European Journal of Pharmacology Dec 1982The effects of acute administration of phencyclidine (PCP) on the steady state levels of methionine-enkephalin in discrete brain areas were investigated in mice. The...
The effects of acute administration of phencyclidine (PCP) on the steady state levels of methionine-enkephalin in discrete brain areas were investigated in mice. The methionine-enkephalin levels in the medulla oblongata-pons and the midbrain were decreased by the administration of PCP. However, PCP induced no change of the methionine-enkephalin levels in other brain areas at the dose range of 5-20 mg/kg. These results suggest that the pharmacological effects of PCP may involve changes in enkephalinergic neuronal activity.
Topics: Animals; Brain Chemistry; Depression, Chemical; Enkephalin, Methionine; Male; Mice; Mice, Inbred Strains; Phencyclidine; Time Factors
PubMed: 7160437
DOI: 10.1016/0014-2999(82)90325-9 -
Zeitschrift Fur Naturforschung. C,... 2001The possible involvement of opioid system in the regulation of hemolymph glucose level in the fresh water crab Oziotelphusa senex senex Fabricius, was investigated....
The possible involvement of opioid system in the regulation of hemolymph glucose level in the fresh water crab Oziotelphusa senex senex Fabricius, was investigated. Opioid agonist and antagonist was also used in addition to methionine-enkephalin itself. Injection of the opioid, methionine-enkephalin and FK 33-824 significantly elevated hemolymph glucose level. In contrast, injection of naloxone in to crab resulted in decrease in hemolymph glucose level. Injection of naloxone prior to injection of methionine-enkephalin blocked the hyperglycemic action of methionine-enkephalin. Injection of methionine-enkephalin, FK 33824 and naloxone produced no significant effect on hemolymph glucose level in eyestalk-less crab. The alterations in the intact crab hemolymph glucose level hypothesised to be due to stimulation of release of hyperglycemic hormone during methionine-enkephalin and FK 33824 treatment and blocking of release of hyperglycemic hormone during naloxone treatment from the eyestalks of crab Oziotelphusa senex senex.
Topics: Animals; Brachyura; D-Ala(2),MePhe(4),Met(0)-ol-enkephalin; Enkephalin, Methionine; Fresh Water; Glucose; Hemolymph; Homeostasis; Naloxone
PubMed: 11531100
DOI: 10.1515/znc-2001-7-824 -
Journal of Peptide Science : An... Jul 2005Studies with cultured tumour cell lines are widely used in vitro to evaluate peptide-induced cytotoxicity as well as molecular and biochemical interactions. The...
Studies with cultured tumour cell lines are widely used in vitro to evaluate peptide-induced cytotoxicity as well as molecular and biochemical interactions. The objectives of this study were to investigate the influence of the cell culture medium on peptide metabolic stability and in vitro antitumour activity. The degradation kinetics of the model peptide methionine enkephalin (Met-E, Tyr-Gly-Gly-Phe-Met), demonstrated recently to play an important role in the rate of proliferation of tumour cells in vitro and in vivo, were investigated in cell culture systems containing different amounts of fetal bovine serum (FBS). The influence of enzyme inhibitors (bestatin, captopril, thiorphan) on the Met-E degradation was also investigated. The results obtained in the Dulbecco's modified Eagle medium containing 10% FBS indicated a rapid degradation of Met-E (t(1/2) = 2.8 h). Preincubation of the medium with a mixture of peptidase inhibitors reduced the hydrolysis of Met-E, as shown by the increased half-life to 10 h. The in vitro activity of Met-E against poorly differentiated cells from lymph node metastasis of colon carcinoma (SW620) and human larynx carcinoma (HEp-2) cells was determined. Tumour cells were grown for 3 weeks prior to the experiment in a medium supplemented with 10%, 5% or 2% FBS. Statistically significant to mild or no suppression of cell proliferation was observed in all cultures. In both cell lines, a significant suppression of cell growth by a combination of peptidase inhibitors and Met-E, compared with cells exposed to the peptide alone and cells grown in the absence of Met-E, was observed. This study indicated that caution must be exercised in interpreting the antiproliferative effects of peptide compounds in conventional drug-response assays.
Topics: Antineoplastic Agents; Cell Proliferation; Culture Media; Drug Screening Assays, Antitumor; Enkephalin, Methionine; Humans; Tumor Cells, Cultured
PubMed: 15685713
DOI: 10.1002/psc.643 -
Peptides 1993In the conscious dog, intravenous administration of methionine-enkephalin produces simultaneous increases in both heart rate (HR) and mean arterial blood pressure (MAP)....
In the conscious dog, intravenous administration of methionine-enkephalin produces simultaneous increases in both heart rate (HR) and mean arterial blood pressure (MAP). This report describes both depressor and cardioaccelerator responses to methionine-enkephalin (10 micrograms/kg IV) in conscious dogs following acute hypotension induced by either bolus injection of isoproterenol (0.1-5.0 micrograms/kg IV) or infusion of sodium nitroprusside (SNP, 3-8 micrograms/kg/min). Cardiovascular responses to methionine-enkephalin were blocked by naloxone. Pretreatment of the dogs with the beta-adrenergic receptor antagonist propranolol failed to prevent the hypotensive response to methionine-enkephalin following SNP infusion. The results indicate that the hemodynamic responses to methionine-enkephalin can be altered by acute manipulation of blood pressure. These results may have implications relative to the role of endogenous opiates in regulation of blood pressure, especially in acute hypotensive states.
Topics: Animals; Blood Pressure; Dogs; Enkephalin, Methionine; Female; Heart Rate; Isoproterenol; Male; Naloxone; Nitroprusside; Propranolol
PubMed: 8332544
DOI: 10.1016/0196-9781(93)90130-9