Hansjörg Teschemacher

Elevated plasma β-endorphin levels in pregnant women and their neonates

Abstract Using radioimmunoassay technique β-endorphin levels were measured in the plasma of women undergoing labour and partirition and in the plasma of their neonates. The level of immunoreactive β-endorphin in the plasma of women undergoing labour was found to be significantly elevated (mean values: 38–135 fmoles/ml) above the levels found in non-pregnant women (mean values: 5–10 fmoles/ml). After birth, the level of β-endorphin-like immunoreactivity in maternal venous plasma was significantly higher than that in the umbilical vein and artery plasma of the new-borns, but there was no arterio-venous difference in the neonatal plasma. Since the antiserum used displayed the same avidity for human β-endorphin and β-lipotropin chromatographic separation of the immunoreactive components was performed by gelfiltration. Both peptides were found in the plasma of non-pregnant women, in maternal plasma and in the plasma of the neonates. In addition, high amounts of both peptides were found in the fetal pituitary gland showing that the fetus can probably produce its own peptides.

Demonstration of a β-casomorphin immunoreactive material in the plasma of newborn calves after milk intake

Blood was collected from newborn calves before and after their first milk intake after birth; extracts of plasma were assayed by radioimmunoassay for the presence of beta-casomorphin-7 immunoreactive materials. No beta-casomorphin immunoreactivity was found in samples collected before milk ingestion; however, in samples collected after milk ingestion a beta-casomorphin-7 immunoreactive material was detected. Chromatographic characterization showed that this material was not identical with beta-casomorphin-7 but might rather represent a precursor thereof. The material proved resistant to enzymatic attack during a 30-min incubation period at 37 degrees C in the plasma of newborn calves, whereas beta-casomorphin-7 was degraded under these conditions. A physiological significance of beta-casomorphin-7 eventually cleaved from such a precursor material at any site in the newborn mammal is suggested.

Opioid activities of human β-casomorphins

SummaryOpioid activities of human β-casomorphin-4,-5,-7 and -8 and, for comparison, of the corresponding bovine β-casomorphins were studied in the guinea-pig ileum preparation. Binding parameters, i.e. Kd-values and binding site concentrations, for the interaction of human and bovine β-casomorphins with opioid receptors in rat brain homogenates were determined in inhibition experiments, using [3H]-(d-Ala2, MePhe4, Gly-ol5)enkephalin, [3H]-(d-Ala2, d-Leu5)enkephalin and [3H]ethylketazocin as μ-, δ- and κ-opioid receptor ligands. Analysis of binding data was performed using a non-linear curve fitting program. All β-casomorphins examined displayed opioid activity. The affinity was highest for μ-receptors, less so for δ-receptors and lowest for κ-receptors. It is suggested that human β-casomorphins might play a role as “food hormones”.

Studies of the enzymatic degradation of β-casomorphins

Abstract β-Casomorphins (β-CMs), although known to be highly resistant to proteolytic enzymes, are demonstrated to be rapidly degraded in bovine or rat plasma. Degradation of these peptides consisting of the amino acid sequence TYR-PRO-PHE-GLY-PRO-ILE and C-terminally shortened fragments thereof, may be due to an enzyme identical with or similar to the dipeptidyl-peptidase IV (DP IV) which is known to cleave dipeptide fragments from the N-terminus of peptides after proline residues. This assumption is compatible with the finding that β-casomorphin (β-CM) analogues in which the proline residue in position two has been replaced by D-alanine, seem to be completely resistant to enzymatic attack in the plasma.

Human β-casomorphin-8 immunoreactive material in the plasma of women during pregnancy and after delivery

Human β-casein contains fragments with opioid activity, which have been termed “human β-casomorphins”1,2.

Opioid peptides: do they have immunological significance?

Abstract Almost a decade after the discovery of the endogenous opioids, their physiological role is still nuclear. Hansjorg Teschemacher and Lothar Schweigerer describe recent studies which indicate that opioid peptides might have immunological significance. These peptides can modulate several immune functions and appear to be constituents of the immune system themselves. It is possible that opioid peptides are involved in the immune response to stress or even in the immune defence against neoplastic disease.

β-endorphin: Interaction with specific nonopioid binding sites on EL4 thymoma cells

Binding of 125I-labeled camel beta-endorphin (125I-beta C-endorphin) to cells of several mouse thymoma cell lines was examined and was highest to EL4 cells. 125I-beta C-endorphin binding to EL4 cells was temperature-dependent; it was further characterized at 4 degrees C and exhibited saturability, complete reversibility, structural specificity and pH-dependence. 125I-beta C-endorphin binding was not inhibited by the opioid pentapeptides [Leu] enkephalin or [Met] enkephalin (which share common sequences with the N-terminus of beta C-endorphin) or by the N-terminal beta C-endorphin fragments beta C-endorphin (1-16) or beta C-endorphin (1-27). In contrast, binding was inhibited by beta C-endorphin (1-31), indicating that beta C-endorphin binding to EL4 cells was with a C-terminal beta C-endorphin segment. We suggest that binding of beta-endorphin to such nonopioid binding sites may precede its apparent effects on the proliferation of T-lymphocytes (5,6).

Release of β-endorphin immunoreactive material under perioperative conditions into blood or cerebrospinal fluid: Significance for postoperative pain?

The function of beta-endorphin immunoreactive material (IRM) released under perioperative conditions remains to be clarified. In 17 patients undergoing orthopedic surgery, we determined beta-endorphin IRM in venous blood plasma and in cerebrospinal fluid (CSF) before surgery (t(A)); after termination of surgery and general anesthesia, but still under spinal anesthesia (t(B)); on occurrence of postoperative pain (t(C)); and 1 day after the operation (t(D)). Pain severity was rated by the patients by using a visual analog scale. Patients felt postoperative pain (t(C)), but they felt no pain at times t(A), t(B), and t(D). beta-Endorphin IRM plasma levels before surgery (t(A)) or with postoperative pain (t(C)) proved to be significantly higher than levels determined just after surgery, but still under spinal anesthesia (t(B)), or those determined 1 day after the operation (t(D)); beta-endorphin IRM plasma levels at times t(A) and t(C) correlated positively with postoperative pain severity (t(C)). beta-Endorphin IRM CSF levels after surgery, but still under spinal anesthesia (t(B)), were significantly higher than levels determined at times t(A), t(C), or t(D). No correlation was found between beta-endorphin IRM CSF levels and pain severity. In conclusion, postoperative pain severity appears to be related to beta-endorphin IRM levels in plasma before surgery as well as with postoperative pain; the analgesic significance of this material remains to be elucidated.

Diminution of contractile response by κ-opioid receptor agonists in isolated rat ventricular cardiomyocytes is mediated via a pertussis toxin-sensitive G protein

Opioids directly decrease the contractile response of isolated ventricular cardiomyocytes to electrical stimulation. To investigate whether these effects are mediated via GTP-binding Gi/o proteins we examined the influence of pertussis toxin on the effects of the κ-opioid receptor agonist trans-(±)-3,4-dichloro-N-methyl-N-[2-(1-pyrrolidinyl)-cyclohexyl]-benzeneacetamide (U-50,488) methanesulphonate and on the as yet undescribed effects of the opioid peptide dynorphin A (1–8) on contraction. In isolated, electrically driven, rat ventricular cardiomyocytes both agents concentration dependently reduced cell shortening within 15 min, decreasing the contractile response by 79±4% (n=5) and 62±2% (n=6) of control values at maximal effective concentrations of 10 µM (U-50,488) and 1 µM [dynorphin A (1–8)], respectively. Pertussis toxin pre-treatment (200 ng/ml; 4.5–5 h) completely abolished the effects of U-50,488 and dynorphin A (1–8) on the contractile response, indicating that these effects are mediated via Gi/o proteins. In addition, the non-selective opioid receptor antagonist (–)-naloxone and the κ-opioid receptor antagonist nor-binaltorphimine antagonized the effects of U-50,488 and dynorphin A (1–8) on the contractile response. Furthermore, the µ- and δ-opioid receptor agonist (D-Ala2, D-Leu5)-enkephalin (DADLE) had no effects on contraction. These results indicate that the decrease in cell shortening is due to stimulation of κ-opioid receptors. The direct effect of κ-opioid receptor agonists on the contractile response thus represents an additional mechanism for decreasing cardiac contractility, besides the M-cholinoceptor- or adenosine receptor-mediated pathway. It is conceivable that increased release of endogenous dynorphins from the heart during hypoxia may protect the heart in a similar manner to adenosine.

Determination of β-Endorphin and Fragments Thereof in Human Plasma Using High-Performance Liquid Chromatography and a Multiple Radioimmunoassay System

A method for the determination of β-endorphin and β-endorphin fragments in human plasma was developed. β-Endorphin-related peptides were extracted from plasma using octadecasilyl-silica cartridges. Extracts were subjected to re versed-phase high-performance liquid chromatography (HPLC). Extracts as well as HPLC column eluates were assayed using a multiple radioimmunoassay system; several antibodies directed against various distinct regions of the β-endorphin molecule were employed. Using this method, evidence for the presence of multiple β-endorphin fragments in the plasma of healthy young volunteers (under normal conditions) was obtained.