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PubMed1985

Modulation of macrophage-mediated tumoricidal activity by neuropeptides and neurohormones.

Recent evidence has suggested that stress may suppress the immune system and increase the frequency and severity of viral and neoplastic disease. The mechanisms for stress-induced modulation of immune function are unclear, but several neuropeptides are thought to be involved. Because macrophages play an important role in the host defense against infection and neoplasia, several stress-related neuropeptides were screened in efforts to determine whether these substances affect macrophage-mediated tumoricidal activity. Adrenocorticotropin and noradrenaline each completely blocked the capacity of mouse recombinant interferon-gamma (INF-gamma) to activate murine peritoneal macrophages to a tumoricidal state as measured by the lysis of 125I-UdR-labeled melanoma target cells. Vasoactive intestinal peptide significantly potentiated the suppressive effects of noradrenaline. In contrast, neurotensin markedly enhanced the cytolytic capability of peritoneal macrophages activated with INF-gamma. Several other neuropeptides, including substance P, alpha-endorphin, beta-endorphin, Leu-enkephalin, and Met-enkephalin, had no effect on macrophage activation. These findings demonstrate that selected stress-related neuropeptides and neurohormones significantly modulate the capacity of macrophages to attain a tumoricidal state and suggest that alteration of macrophage function by neuropeptides may be a prominent feature of stress-induced enhancement of neoplastic disease.

Adjuvants, Immunologic↗
PubMed1985

Identification of N alpha-acetyl-alpha-endorphin and N alpha-acetyl-gamma-endorphin isolated from the neurointermediate lobe of the rat pituitary gland.

The peptides that represent the major components with alpha-endorphin- and gamma-endorphin-like immunoreactivity in the rat neurointermediate lobe were purified to homogeneity and chemically characterized. Rat neurointermediate lobes were extracted by boiling and homogenization in acetic acid. Peptide purification was based on gel filtration, followed by two high-pressure liquid chromatography steps. Pools containing peptides with the size and immunochemical properties of alpha- and gamma-endorphins were resolved by reverse-phase high-pressure liquid chromatography into multiple immunoreactive components. The major forms were finally purified by paired-ion high-pressure liquid chromatography. The amino acid compositions of these peptides fitted the beta-endorphin sequences 1-16 and 1-17. Tryptic mapping, aminopeptidase M digestion, chromatographic characterization, and immunoreactivity to an antiserum recognizing the N alpha-acetylated terminus of endorphins showed that these peptides were indistinguishable from N alpha-acetyl-alpha-endorphin (N alpha-acetyl-beta-endorphin 1-16), and N alpha-acetyl-gamma-endorphin (N alpha-acetyl-beta-endorphin 1-17). The NH2-terminal residue of the peptides was identified by mass spectrometry as N alpha-acetyltyrosine, substantiating the identity of the peptides. The results demonstrate the existence of N alpha-acetylated alpha- and gamma-endorphin as endogenous peptides in the neurointermediate lobe of the rat pituitary gland. In view of their occurrence and biological properties they should be considered significant members of the pro-opiomelanocortin family.

Amino Acids↗
PubMed1986

beta-Endorphin augments the cytolytic activity and interferon production of natural killer cells.

We have investigated the in vitro effects of the neurohormone beta-endorphin (b-end) on natural killer (NK) activity and interferon (IFN) production mediated by large granular lymphocytes (LGL). LGL-enriched fractions from peripheral blood mononuclear cells (PBMC) from normal human volunteers were obtained by fractionation over discontinuous Percoll gradients. LGL were preincubated with or without various concentrations of b-end or the closely related peptides alpha-endorphin (a-end), gamma-endorphin (g-end), or D-ALA2-beta-endorphin (D-ALA2-b-end), a synthetic b-end analogue. NK activity was assayed on 51Cr-labeled K562 target cells. Preincubation of LGL effectors (but not K562 targets) for 2 to 18 hr with concentrations of b-end between 10(-7) M and 10(-10) M produced significant augmentation of NK cytolytic activity (mean percentage increase: 63%). The classic opiate antagonist naloxone blocked the enhancing effect when used at a 100-fold molar excess relative to b-end. Neither a-end nor g-end could augment NK activity, whereas D-ALA2-b-end produced an enhancement comparable with that produced by b-end. In addition, incubation of LGL with b-end in the presence of phytohemagglutinin or poly I:C significantly augmented IFN production. These findings demonstrate that b-end enhances NK activity and IFN production of purified LGL, and suggests that b-end might bind to an opioid receptor on LGL that can be blocked by naloxone. These results lend support to the concepts of regulation of the immune response by neurohormones and the functional relationship between the nervous and immune systems.

Adjuvants, Immunologic↗
PubMedDate not supplied

Non-opiate effects of neuropeptides derived from beta-endorphin.

Brain enzymes convert the opioid peptide beta-endorphin (beta E-(1-31)) to alpha- and gamma-endorphin and to several non-opioid fragments by further cleavage of the tyrosine residue or acetylation. Several of these peptides selectively affect brain functions. alpha-Endorphin (beta E-(1-16)) and relate non-opioid fragments (beta E-(2-16), beta E-(2-9) a.o.) like amphetamine, delay extinction of pole-jumping avoidance behavior and facilitate passive avoidance behavior. In addition these peptides enhance the stereotyped sniffing response induced by the injection of apomorphine into the nucleus caudatus. The fragment beta E-(10-16) inhibits, like serotonin and antidepressants, the behavioral effects of melatonin injected into the nucleus accumbens. gamma-Endorphin (beta E-(1-17)) has inherent opioid and neuroleptic-like properties, e.g. demonstrated by a naloxone reversible inhibition of hypermotility induced by apomorphine following injection into the nucleus accumbens. Also the non-opioid gamma-type endorphins (e.g. DT gamma E (beta E-(2-17) and DE gamma E (beta E-(6-17)) mimic certain effects of neuroleptics. These peptides facilitate extinction of pole-jumping avoidance behavior, attenuate passive avoidance behavior and antagonize the hypomotility and stereotyped sniffing induced by apomorphine injected into the nucleus accumbens and pyriform cortex respectively. These and other behavioral studies, including grasping responses, brain stimulation reward, food and other positively rewarded behavior, indicate that the action of alpha-type endorphins is in some aspects comparable to that of psychostimulants, while the effects of gamma-type endorphins are comparable to those of classical as well as atypical neuroleptics. Indeed, gamma-type endorphins have antipsychotic effects in a category of schizophrenic patients.

Animals↗
PubMed1985

Suppression of T lymphocyte chemotactic factor production by the opioid peptides beta-endorphin and met-enkephalin.

The opioid peptides beta-endorphin and met-enkephalin have been shown to modulate human lymphocyte proliferation, mononuclear cell locomotion, natural killer cell activity, and neutrophil locomotion. This study demonstrates that beta-endorphin and met-enkephalin inhibit the production of a T lymphocyte chemotactic factor (LCF) by concanavalin A (Con A)-stimulated peripheral blood mononuclear cells. Inhibition of LCF production was observed by using concentrations of 10(-11) to 10(-6) M beta-endorphin or met-enkephalin but not alpha-endorphin. A bimodal pattern of suppression of LCF production was observed with both met-enkephalin and beta-endorphin when titrated from 10(-12) to 10(-6) M concentrations, with the peaks of suppressive activity occurring at concentrations of 10(-11) M and 10(-6) M. Timed studies of the production of LCF over a 54-hr period showed that there was an appreciable lag in the onset of measurable LCF activity in mononuclear supernatants produced in the presence of beta-endorphin and met-enkephalin. The suppression of LCF production mediated by opioid peptides in mononuclear supernatants was abrogated by depletion of glass-adherent mononuclear cells before culturing with opioids and Con A. The inhibitory effect of opioid peptides on LCF production was prevented by the addition of indomethacin to cell cultures. Additional experiments showed that exogenous prostaglandin E2 (PGE2) suppressed Con A-stimulated LCF production when added at concentrations ranging from 10(-6) to 10(-8) M. Other studies suggested that the mechanism of opioid peptide-mediated suppression of LCF production was due to an enhanced sensitivity of mononuclear cells to the inhibitory action of PGE2. These data provide further evidence for modulation of the immune response in humans by the neuroendocrine hormones beta-endorphin and met-enkephalin and further suggest a link between this modulation and arachidonic acid metabolism.

Cell Separation↗
PubMed1985

Monoclonal antibody to enkephalins with binding characteristics similar to opiate receptor.

Monoclonal antibodies to enkephalins were established by immunization of mice with met-enkephalin, leu-enkephalin or both. Twenty-three clones with a high titer were classified into 6 types according to the binding properties to enkephalins and their derivatives. Antibody LM 239 showed binding characteristics similar to opiate receptor. It has a very high affinity to enkephalins and their derivatives which have a potent opioid activity, but a low affinity to enkephalin derivatives which devoid of opioid activity. The binding of 3H-met-enkephalin to the antibody was inhibited by naloxone and morphine, although the ID50 values were considerably higher than the Ka values of the alkaloids to opiate receptor.

Animals↗
PubMed1986

Immunohistological detection of methionine-enkephalin-like and endorphin-like material in the digestive tract and in the nervous system of the mussel: Mytilus edulis L.

Using the indirect immunofluorescence technique, methionine-enkephaline-like, alpha- and beta-endorphin-like peptides were detected on whole body sections of Mytilus edulis L. Met-enkephalin-like immunoreactivity was localized in the epithelium of the digestive tract, in the hepatopancreas, and in the nervous system. The immunoreactive cell bodies were very abundant in the anterior gastric epithelium, but sparse in the terminal portion of the digestive tract. By their basal processes the immunoreactive cells were in contact with a plexus of immunoreactive cells and fibers located in the connective tissue underlying the digestive epithelium. In the principal hepatopancreatic ducts, isolated cells showing met-enkephalin-like immunoreactivity were detected between the epithelial cells and the basal lamina. A few immunoreactive cells and fibers were observed between the hepatopancreatic tubules. The three pairs of nervous ganglia contained in their cortical layer numerous met-enkephalin-like immunoreactive perikarya. Their central area possessed fluorescent immunoreactive bundles of fibers extending to the commissures, the connectives, and the nerves. Met-enkephalin-like immunoreactive fibers were detected between the smooth muscle cells. At the surface of these smooth muscle cells, immunopositive met-enkephalin-like tapered nervous endings were observed. The alpha- and beta-endorphin antisera produced a positive immunoreaction in some gastric epithelial cells, in some perikarya of the pedal ganglia, and in some nervous fibers. The endorphin-like structures were far less abundant than the met-enkephalin-like structures, but very close to them.

Animals↗
PubMed1988

Increased concentration of alpha- and gamma-endorphin in post mortem hypothalamic tissue of schizophrenic patients.

The concentrations of alpha-, beta- and gamma-endorphin were determined by radioimmunoassay in HPLC fractionated extracts of post mortem hypothalamic tissue obtained from schizophrenic patients and controls. The hypothalamic concentration of alpha- and gamma-endorphin was significantly higher in patients than in controls (+72.9% and +50.5% respectively). No difference was found in the concentration of beta-endorphin, the putative precursor of alpha- and gamma-endorphins. These results suggest a deviant metabolism of beta-endorphin in the brain of schizophrenic patients. Whether this phenomenon is related to the psychopathology, or is a consequence of ante mortem farmacotherapy, remains to be established.

Adult↗
PubMedDate not supplied

B-lipotropin 61-76 and 61-91 fragments act as transglutaminase substrates in vitro.

Both alpha- and beta-endorphin were shown to incorporate radioactive polyamines during incubation in the presence of purified transglutaminase and Ca2+, spermine acting as the best acyl acceptor substrate. The endorphin labelling is dependent on the time of exposure to the enzyme and on the substrate concentration. In the absence of acyl acceptor polyamines, isotopically labelled beta-endorphin gives rise to high molecular weight radioactive polymer(s). Moreover, when different proteins acting as transglutaminase substrates are added, beta-endorphin produces heterologous structures. These data indicate that the glutamine-71 of the beta-lipotropin chain, contained in both alpha- and beta-endorphin, functions as acyl donor substrate for the enzyme and that at least one beta-endorphin lysyl residue can serve as acyl acceptor.

Endorphins↗
PubMed1986

In vitro effects of endogenous opiate peptides on thyrotropin function: inhibition of thyrotropin-releasing hormone release and absence of effect on thyrotropin release.

Thyrotropin-releasing hormone (TRH) or thyroid-stimulating hormone (TSH) was measured by radioimmunoassay in the incubation medium of rat hypothalami or anterior pituitary halves, respectively. We studied the effect of opioid peptide addition (10(-8) to 10(-6) M) on TRH or TSH release. alpha- or beta-Endorphin decreased TRH release in a dose-dependent manner while only 10(-6) M Leu- or Met-enkephalin decreased TRH release. These inhibitory effects were prevented by addition of naloxone (10(-5) M). In the dose range used none of the opioid peptides modified TSH release. These results indicate that opioid peptides may play a role in the regulation of thyrotropin secretion via a hypothalamic action on TRH release.

Animals↗
PubMed1987

Differential effects of beta-endorphin fragments on human natural killing.

The endogenous opiate peptide, beta-endorphin, has two effects on human natural killing (NK). Preincubation of effector lymphocytes with between 10(-7) and 10(-11) M beta-endorphin increases NK. Preincubation with lower concentrations results in a reduction in NK. Endorphin peptides containing an unmodified N-terminal sequence, and which are known to bind only to opiate receptors, increase NK. Sequences reported to bind only to nonopiate receptors reduce NK.

Cytotoxicity, Immunologic↗
PubMed1985

High-performance liquid chromatographic analysis of in vitro central neuropeptide processing.

Reversed-phase high-performance liquid chromatography (HPLC) was used to study and characterize the in vitro proteolytic processing of beta-endorphin by twice-washed membrane homogenates. A high-resolution method, capable of separating over 30 different human beta-endorphin-related fragments in a single analysis, was used to study the time course of production of specific, biologically active endorphin fragments by membrane-associated proteases. The results demonstrate that frozen (-37 degrees C), postmortem human and rat brains are viable for processing studies and that metabolism proceeds similarly to that in fresh brain homogenates or slices. Significant differences were noted in the formation rates of putative neuroleptic peptides between sex- and age-matched postmortem brain tissues from controls versus postmortem brain tissues from neuropsychiatric patients or drug-treated animals. These data suggest that using HPLC to characterize neuropeptide processing in human or rat membrane-associated enzyme homogenates is both descriptive and quantitative and offers insight into the central regulation of neuropeptide metabolism.

Amino Acid Sequence↗
PubMed1990

[Structural organization of [met]enkephalin and endorphin molecules. II. Theoretical conformation analysis of alpha-, gamma- and delta-endorphins].

Conformational energy calculations were carried out for neuropeptides alpha-, gamma- and delta-endorphins, which are 1-16, 1-17 and 1-19 fragments respectively, of beta-endorphin. The proposed computational scheme yielded all possible low-energy conformational sets for these hormones. Specific features of spatial organization of each compound and similarities of their structures are discussed.

Amino Acid Sequence↗
PubMed1985

[Distribution of alpha-, beta- and gamma-endorphins in the forebrain and diencephalon of the rat brain (immunohistochemical study)].

The investigation performed by means of specific rabbit antisera is one of the stages for mapping peptides. This is necessary for revealing functional role of the endorphins in the CNS. The indirect method of Coons is applied in parallel series of frontal paraffin slices of the brain 10 mcm thick. Neurons containing alpha-, beta- and gamma-endorphins are localized in the same brain areas. These are structures of the palaeocortex (the prepiriform cortex and the diagonal area) and those of the hypothalamus (the supraoptic, arcuate, ventromedial, mammillary nuclei, anterior and posterior fields). Endorphinergic neural fibers run within composition of various conducting cerebral systems, such as the corpus collosum, fornix, internal and external capsules.

Animals↗
PubMed1985

[Bronchial asthma and endorphins].

The paper deals with the investigation of endorphin content in the blood of patients with asthma. The increase in alpha- and beta-endorphin concentration was shown to depend on the severity of clinical manifestations of infectious-allergic and atopic forms of bronchial asthma. This regularity was not observed for gamma-endorphin. The infectious-allergic form of asthma was characterized by drastic reduction in the content of all three endorphin types upon treatment with dexamethasone. The possible role of endorphin reactions in the pathogenesis of asthma is discussed.

Adolescent↗