It has previously been demonstrated that met-enkephalin, and endogenous opiate, stimulates gastric acid secretion in man, while naloxone inhibits meal-stimulated acid secretion. In seven healthy subjects the opiate receptor antagonist naloxone was infused in a dose of 10 microgram/kg/h during stimulation of gastric acid secretion with pentagastrin 100 ng/kg/h and met-enkephalin 0.1 microgram/kg...

The effects of injection of a peptidase-resistant analog of methionine-enkephalin, [D-ala2]-methionine-enkephalin, on blood pressure (BP), heart rate, and vasopressin release were studied in spontaneously hypertensive rats (SHR). Intravenous injection of [D-Ala2]-methionine-enkephalin (DAME) increased BP in both SHR and normotensive Wistar-Kyoto (WKY) controls, with a significantly greater incr...

An efficient approach for the synthesis of norbuprenorphin derivatives through coupling of enkephalins and norbuprenorphine intermediate is described. Norbuprenorphine derivative was synthesized from thebaine and then, its reaction with succinic acid and phthalic acid was also studied. Meanwhile, the synthesis of enkephalins was done using solid phase peptide synthesis approach. Furthermore, af...

An efficient approach for the synthesis of norbuprenorphin derivatives through coupling of enkephalins and norbuprenorphine intermediate is described. Norbuprenorphine derivative was synthesized from thebaine and then, its reaction with succinic acid and phthalic acid was also studied. Meanwhile, the synthesis of enkephalins was done using solid phase peptide synthesis approach. Furthermore, af...

A highly sensitive and specific radioimmunoassay for three enkephalins (opiate-like pentapeptides) has been developed. The assay utilizes 12SI-labeled enkephalins and antisera raised in rabbits, to synthetic enkephalins coupled with glutaraldehyde to bovine serum albumin. These antisera show ~1% cross-reactivity between H,N-Tyr-Gly-GlyPhe-Met-OH ([MeVlenkephalin) and H,N-Tyr-Gly-Gly-PheLeu-OH (...

PURPOSE The aim of the study was to assess the liver Met-enkephalin concentration in chronic viral hepatitis type B and C as well as in liver cirrhosis in order to estimate the role of opioid system in pathogenesis of liver disease. MATERIAL AND METHODS The concentration of Met-enkephalin was examined in liver tissue of 103 consecutive patients with chronic hepatitis type B and C. Control gro...

[~-Ala~,Leu~,Cys~]Enkephalin (DALCE) is a synthetic enkephalin analog which contains a sulfhydryl group. DALCE binds with high affinity to &receptors, with moderate affinity to preceptors, and with negligible affinity to K-receptors. Pretreatment of rat brain membranes with DALCE resulted in concentrationdependent loss of &binding sites. Using 2 nM ['H][DPen2,~-Pen5]enkephalin (where Pen repres...

Studies were performed to investigate the effects of the endogenous opioid peptide methionine enkephalin on experimental metastasis of the murine B-16 melanoma and on murine splenic natural killer cell activity. Methionine enkephalin was shown to significantly inhibit tumor metastasis and significantly enhance splenic natural killer cell activity. These results indicate that the endogenous opio...