The existence of opioid receptors in mammalian myometrial tissue is now widely accepted. Previously enkephalin degrading enzymes have been shown to be elevated in pregnant rat uterus and a met-enkephalin analogue has been shown to alter spontaneous contractility of rat myometrium. Here we have undertaken studies to determine the effects of met-enkephalin on in vitro human myometrial contractili...

A new N-protecting group, ethanesulfonylethoxycarbonyl (Esc), was designed to perform peptide synthesis in both aqueous and organic solvents. Esc-amino acids were prepared by the reaction of Esc-Cl and amino acids. Although Esc-Cl was a highly reactive reagent, it was not stable and decomposed during the purification procedure. A more stable reagent, ethanesulfonylethyl-4-nitrophenyl carbonate ...

The biosynthesis and posttranslational proteolytic processing of proenkephalin was studied in three projection systems in the rat central nervous system--the caudate-putamen to the globus pallidus, the paraventricular nucleus of the hypothalamus to the median eminence, and the mossy fiber system of the granule cells of the hippocampus. By using the techniques of in vivo radiolabeling and sequen...

In order to test the possible effect of chronic treatment with met-enkephalin upon the LH-adenohypophyseal cells, an immunohistochemical-morphometric study was carried out in rats of both sexes receiving a daily dose of 40 micrograms of met-enkephalin intramuscularly over 15 days. Following the administration of the opioid, a drastic decrease in the cellular, cytoplasmic and nuclear areas when ...

Met-Enkephalin injected i.c.v. attenuated stress-induced increases in levels of 3-methoxy-4-hydroxyphenylethyleneglycol sulfate, the major metabolite of brain noradrenaline, in the hypothalamus, amygdala, hippocampus, thalamus, midbrain and LC region in rats. The data suggest that Met-enkephalin acts to attenuate stress-induced increases in noradrenaline turnover in these brain regions in rats.

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. The results show that cells become tolerant to, and dependent upon, enkephalin.

The simultaneous addition of [D-Ala2, D-Leu5]-enkephalin and morphiceptin at concentrations at which 98% of enkephalin (delta) and morphine (mu) receptors are occupied only partially inhibits the binding of [3H]diprenorphine to rat brain membranes. These conditions, furthermore, do not affect the curves for displacement of [3H]diprenorphine binding by unlabeled diprenorphine. These data suggest...

The globus pallidus and ventral pallidum receive dense enkephalinergic innervation from the dorsal and ventral striatum, respectively. A previous study demonstrated peripheral morphine administration to increase pallidal enkephalin release. To determine whether such opioid stimulatory effects may be mediated directly in the pallidum, in vivo microdialysis was used to study the effects of local ...

1. The central blood pressure effects of the enkephalin analogue, D-Ala'-Met-enkephalin were investigated in normotensive rats and in spontaneously hypertensive rats. 2. In conscious Wistar rats, injection of 1.7, 17 and 170 nmol of D-Ala'-Met-enkephalin into the lateral brain ventricle produced dosedependent blood pressure increases of 5 + 3 f 1 8, 10.5 f 2.8 and 15.3 f 3.0 mmHg respectively. ...