BACKGROUND Opioid peptides released from immunocytes during inflammation and stress in critically ill patients are associated with an altered immune response. Moreover, concentrations of opioid peptides are increased in peripheral blood and at the sites of inflammatory reactions. METHODS Using flow cytometric assay of whole human blood, we investigated direct effects of endogenous and synthet...

Sensory neurons grown in dispersed cell culture in the absence of non-neuronal cell types contain immunoreactive substance P that is chemically similar to synthetic substance P. When depolarized in high-K+ media (30-120 mM), the neurons release this peptide by a Ca2+-dependent mechanism. An enkephalin analogue, [D-Ala2]enkephalin amide, at 10 micron inhibits the K+-evoked release of substance P...

A method that combines intracellular recording, dye marking, and immunocytochemistry makes the study of functional and morphological aspects of enkephalin neurons in the magnocellular preoptic nucleus of the goldfish hypothalamus feasible. By use of multiple techniques, enkephalin neurons can be distinguished from other brain cells and can be reconstructed from drawings of serial sections conta...

Enkephalins play a major role in reproductive physiology in crustaceans; however their role in reproductive development in insects is largely unknown. We investigated the effect of exposure to exogenous leucine-enkephalin (Leu-Enk), methionine-enkephalin (Met-Enk), and the opioid antagonist naloxone on gonad development in the Eastern lubber grasshopper, Romalea microptera. Injection of either ...

Regulation of cellular content of the endogenous opioid peptides Met5-enkephalin and Leu5-enkephalin was investigated in neuroblastoma X glioma hybrid cells NG108-15 grown in both serum-supplemented and serum-free defined media. Untreated cells and cells induced to differentiate were stained using anti-Met5-enkephalin and anti-Leu5-enkephalin with the peroxidase-antiperoxidase immunocytochemica...

Modulation of depolarization-activated ionic conductances by opioid receptor agonists was investigated in isolated parasympathetic neurons from neonatal rat intracardiac ganglia by using the whole cell perforated patch clamp technique. Met-enkephalin (10 muM) altered the action potential waveform, reducing the maximum amplitude and slowing the rate of rise and repolarization but the afterhyperp...

Adrenal enkephalin-containing peptides are known to increase 10- to 15-fold in the rat after surgical denervation of the gland. In this report we show that the increase is preceded by a lag of several hours, which is indicative of stimulation of protein synthesis at the transcriptional level. The major species of newly appearing enkephalin-containing peptide appears to be the intact precursor, ...

Recent histopathological investigations in patients with hepatitis suggested possible involvement of Met-enkephalin and its receptors in the pathophysiology of hepatitis. Consequently, we evaluated the potential hepatoprotective effects of this endogenous opioid pentapeptide in the experimental model of acetaminophen induced hepatotoxicity in male CBA mice. Met-enkephalin exhibited strong hepat...

We have observed two discrete populations of opiate receptors that are differently localized in rat brain. Morphine-like (mu) receptors, labeled by 125I-labeled [D-Ala-2MePhe4Met(O)5-ol]enkephalin, are concentrated selectively in lamina IV of the cerebral cortex, certain thalamic nuclei, and the periaqueductal grey, while delta receptors, labeled by 125I-labeled [D-Ala2-D-Leu5]enkephalin, are m...

Methionine enkephalin and catecholamines were measured in carefully collected plasma samples from 25 patients with cirrhosis and ascites, and 25 with cirrhosis without ascites, 15 disease and 15 healthy controls. Methionine enkephalin was invariably raised in the ascites group, the median value being 4.6-6.9 times that of the other three groups. Similarly, in the ascites group, median noradrena...