Human peripheral blood mononuclear cells are analyzed for preproenkephalin gene expression and peptide processing. Met-enkephalin immunoreactivity as detected with a specific antiserum is found in the cytoplasm of monocytes but not in T lymphocytes. Secretion of met-enkephalin was analyzed with an RIA that is specific for the met-enkephalin pentapeptide. Unfractionated PBMC spontaneously releas...

Binding of Leu-enkephalin and [Rh(III)(η(5)-Cp*)(η(6)-Tyr(1))]Leu-enkephalin to the recently published crystal structures of the μ- and δ-opioid receptor is studied. Docking of free Leu-enkephalin reveals two preferred conformations, one of which suggests an alternative binding site for the tyrosine residue. Furthermore, the three-dimensional solution structure of [Rh(III)(η(5)-Cp*)(η(6)-Tyr(1)...

We have shown previously that enkephalin-containing peptides of high molecular weight increase 10- to 15-fold 3 days after adrenal denervation and have suggested that much of this material may represent newly synthesized proenkephalin. In this paper we report that most of the material appearing after denervation is indeed intact proenkephalin. The putative proenkephalin was partially purified b...

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...

The comparative distribution of Leu-enkephalin and an enkephalin precursor fragment, BAM-22P, was studied in the rat telencephalon using immunocytochemical procedures. Although the enkephalins have previously been localized to telencephalic neurons, the use of high doses of colchicine in the present study has permitted the visualization of widespread enkephalin-containing systems in cortical-li...

Leu-enkephalin is an opioid peptide that has been found to modulate nociception in the spinal cord. Both pre- and postsynaptic interactions by enkephalins have been proposed. By the peroxidase . anti-peroxidase immunocytochemical method, we studied the distribution and ultrastructure of neuronal elements in the monkey dorsal horn to elucidate possible morphological substrates for postulated opi...

The use of very low concentrations of 1251-[D-Ala2,DLeu5]enkephalin, [3H]naloxone, and [3H]dihydromorphine under similar conditions enables the measurement of different opiate binding sites in a rat brain membrane preparation. In the absence of sodium ions, one such site binds enkephalins and their D-Ala2-substituted analogs with higher affinity than morphine and naloxone (enkephalin receptor),...

The distribution of enkephalin-like immunoreactivity within the avian retina was studied by immunofluorescence and immunoperoxidase techniques with antiserum to [Met5]enkephalin and [Leu5]enkephalin. Formaldehyde-fixed retinae were sectioned and incubated in antiserum to either [Met5]- or [Leu5]enkephalin. Specificity to the antiserum was established by absorption of the antiserum with syntheti...

The administration of reserpine increases enkephalin content in rat striatum and adrenal medulla. In order to investigate the mechanisms operative in this increase, we have studied in vivo the dynamic state of enkephalin stores by determining the content of proenkephalin mRNA, enkephalin precursors, and enkephalins in rats receiving reserpine. We measured proenkephalin mRNA by using a cDNA prob...

OBJECTIVE Met- and leu-enkephalins are endogenous opioid neuropeptides with potent analgesic, vasoactive, immunomodulatory and anti-apoptotic properties. We hypothesised that clinical or immunological variables of early systemic sclerosis (SSc) might be correlated to plasma enkephalin levels. METHODS Plasma samples were collected at study entry of the Genetics versus Environment in Scleroderm...