Plasma Levels of Corticotroph-type Pro-opiomelanocortin Derivatives Such as β-Lipotropin, β-Endorphin(1-31), or Adrenocorticotropic Hormone Are Correlated With Severity of Postoperative Pain

Effects of corticotropin-releasing hormone on proopiomelanocortin derivatives and monocytic HLA-DR expression in patients with septic shock

Little is known about interactions between immune and neuro-endocrine systems in patients with septic shock. We therefore evaluated whether the corticotropin-releasing hormone (CRH) and/or proopiomelanocortin (POMC) derivatives [ACTH, β-endorphin (β-END), β-lipotropin (β-LPH), α-melanocyte stimulating hormone (α-MSH) or N-acetyl-β-END (Nac-β-END)] have any influences on monocyte deactivation as a major factor of immunosuppression under septic shock conditions. Sixteen patients with septic shock were enrolled in a double-blind, cross-over and placebo controlled clinical study; 0.5μg/(kgbodyweighth) CRH (or placebo) were intravenously administered for 24h. Using flow cytometry we investigated the immunosuppression in patients as far as related to the loss of leukocyte surface antigen-DR expression on circulating monocytes (mHLA-DR). ACTH, β-END immunoreacive material (IRM), β-LPH IRM, α-MSH and Nac-β-END IRM as well as TNF-α and mHLA-DR expression were determined before, during and after treatment with CRH (or placebo). A significant correlation between plasma concentration of α-MSH and mHLA-DR expression and an inverse correlation between mHLA-DR expression and TNF-α plasma level were found. Additionally, a significant increase of mHLA-DR expression was observed 16h after starting the CRH infusion; 8h later, the mHLA-DR expression had decreased again. Our results indicate that the up-regulation of mHLA-DR expression after CRH infusion is not dependent on the release of POMC derivatives. From the correlation between plasma concentration of α-MSH and mHLA-DR expression, we conclude that in patients with septic shock the down-regulation of mHAL-DR expression is accompanied by the loss of monocytic release of α-MSH into the cardiovascular compartment.

Release of melanotroph- and corticotroph-type proopiomelanocortin derivatives into blood after administration of corticotropin-releasing hormone in patients with septic shock without adrenocortical insufficiency

The aim of the study was to assess the adequacy of pituitary function by determining the plasma concentrations of corticotroph-type (corticotropin, beta-endorphin immunoreactive material [beta-END IRM], authentic beta-END, and beta-lipotropin IRM) as well as melanotroph-type (alpha-melanocyte-stimulating hormone [alpha-MSH] and N-acetyl-beta-END [Nac-beta-END] IRM) proopiomelanocortin (POMC) derivatives in patients under septic shock upon administration of corticotropin-releasing hormone (CRH). The objectives were to assess whether an insufficient release of corticotroph- or melanotroph-type POMC derivatives from the pituitary into the cardiovascular compartment correlates with the 28-day mortality rate. Seventeen patients with septic shock but without adrenocortical insufficiency and 16 healthy volunteers were enrolled in the study, and CRH stimulation tests were performed with an i.v. bolus injection of 100 microg human CRH. After treatment with CRH, plasma concentrations of corticotroph-type POMC derivatives increased in survivors and nonsurvivors, melanotroph-type POMC derivatives such as alpha-MSH or Nac-beta-END IRM increased only in survivors in contrast to nonsurvivors. The release of alpha-MSH and Nac-beta-END IRM was suppressed by dexamethasone in survivors but not in nonsurvivors. In patients with septic shock, the response of the pituitary to CRH stimulation in terms of alpha-MSH or Nac-beta-END IRM release was impaired in nonsurvivors compared with survivors or controls. Reduced responses of alpha-MSH or Nac-beta-END IRM to CRH and the invalid suppression by dexamethasone reflect a state of dysfunction of the melanotroph-type POMC system in nonsurvivors. Considering anticytokine and anti-inflammatory effects of alpha-MSH, this dysfunction may increase the risk of death in patients with septic shock.

Response to delivery stress is not mediated by beta-endorphin (1–31)

OBJECTIVE

The aim of the study was to determine the reaction of the melanotroph and corticotroph-type pituitary proopiomelanocortin (POMC) response to vaginal delivery and caesarean section stress. Furthermore, the relationship between the release of pituitary POMC fragments, gonadotropins and sexual steroids were examined.

STUDY DESIGN

Blood samples were obtained from 10 women in labour on arrival in the birth room (t(A)), at cervix dilatation of 5 cm (t(B)) and immediately after spontaneous delivery (t(C)) and in 16 patients undergoing elective caesarean section before induction of anaesthesia (t(B)) and immediately after delivery (t(C)). Samples were analysed for cortisol, ACTH, authentic beta-endorphin, beta-endorphin immunoreactive material (IRM), acetyl-N-beta-endorphin IRM (NAC), beta-lipotropin (beta-LPH) IRM, oestradiol (E(2)), progesterone (P), prolactin (PRL), FSH and LH.

RESULTS

NAC representing the melanotroph-type pituitary POMC system did not increase during the course of caesarean section or spontaneous labour. In contrast, a significant increase of beta-endorphin IRM, beta-LPH IRM and ACTH were observed, representing an activation of the corticotroph-type POMC system. Highly significant correlations between POMC fragment concentrations during caesarean section and spontaneous labour were also observed. Sexual steroids (E(2) and P) decreased significantly. Except for beta-endorphin IRM and E(2) in course of spontaneous delivery no significant correlation was observed between POMC fragment and gonadotropins or sexual steroids.

CONCLUSION

Caesarean section and spontaneous delivery activated the corticotroph but not the melanotroph POMC system.

Endogenous opiates and behavior: 2006

This paper is the 29th consecutive installment of the annual review of research concerning the endogenous opioid system, now spanning 30 years of research. It summarizes papers published during 2006 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (Section 2), and the roles of these opioid peptides and receptors in pain and analgesia (Section 3); stress and social status (Section 4); tolerance and dependence (Section 5); learning and memory (Section 6); eating and drinking (Section 7); alcohol and drugs of abuse (Section 8); sexual activity and hormones, pregnancy, development and endocrinology (Section 9); mental illness and mood (Section 10); seizures and neurological disorders (Section 11); electrical-related activity and neurophysiology (Section 12); general activity and locomotion (Section 13); gastrointestinal, renal and hepatic functions (Section 14); cardiovascular responses (Section 15); respiration and thermoregulation (Section 16); and immunological responses (Section 17).

Minimal immunoreactive plasma beta-endorphin and decrease of cortisol at standard analgesia or different acupuncture techniques

BACKGROUND AND OBJECTIVE

Acupuncture has been claimed to be associated with activation of the endogenous antinociceptive system. The analgesic effects of acupuncture have been ascribed to beta-endorphin interacting with opioid receptors. However, firstly, the release of beta-endorphin into the blood has been proven to be induced by stress, i.e. under dysphoric conditions, and, secondly, if released under stress, beta-endorphin has been shown not to be analgesic. Our aim was to test whether beta-endorphin immunoreactive material is released into the cardiovascular compartment during acupuncture comparing the most frequently used types of acupuncture with standard pain treatment under apparently low stress conditions.

METHODS

This prospective study included 15 male patients suffering from chronic low back pain. beta-Endorphin immunoreactive material and cortisol were measured in the plasma of patients who underwent, in random order, therapy according to a standard pain treatment, traditional Chinese acupuncture, sham acupuncture, electro acupuncture and electro acupuncture at non-acupuncture points before, at and after the treatment. Statistical analysis was performed using two-way ANOVA with repeated measures.

RESULTS

A decrease in plasma cortisol concentration measured over the five treatment protocols was highly significant (P < 0.001). The beta-endorphin immunoreactive material concentrations in plasma were minimal at all times and in all treatment conditions. The influence of treatments by various acupuncture procedures on cortisol and beta-endorphin immunoreactive material plasma concentrations over the three time points was not significantly different.

CONCLUSIONS

beta-endorphin immunoreactive material in blood is not released by any type of acupuncture as tested under low stress conditions.

Preoperative concentration of beta-lipotropin immunoreactive material in cerebrospinal fluid: a predictor of postoperative pain?

Levels of beta-endorphin immunoreactive material (IRM) in cerebrospinal fluid (CSF) have been reported to correlate inversely with postoperative morphine requirement. Considering proopiomelanocortin (POMC) derivatives as predictors for sensitivity to postoperative pain, we determined authentic beta-endorphin (beta-endorphin(1-31)), beta-lipotropin IRM, N-acetyl-beta-endorphin IRM and ACTH in CSF of 17 patients undergoing hip or knee arthroplasty, before surgery (t(A)), immediately after termination of propofol infusion and still under spinal anesthesia (t(B)), under postoperative pain (t(C)) and one day after surgery (t(D)); patients rated their severity of pain on a visual analogue scale (VAS) at those four times. In all patients CSF concentrations of N-acetyl-beta-endorphin IRM and beta-lipotropin IRM were found to be increased after terminating the propofol infusion with spinal anesthesia still effective at t(B). Patients did not feel pain at times t(A), t(B) or t(D); however, they reported moderate to considerable pain at t(C). There were no correlations of postoperative pain severity at t(C) with ACTH, beta-endorphin(1-31) or N-acetyl-beta-endorphin IRM concentrations in CSF. In contrast, we observed significant inverse correlations (Spearman's rank correlation coefficients between -0.83 and -0.85, p<0.01) for postoperative pain severity with beta-lipotropin IRM concentrations in CSF at t(C), and, in addition, at t(A), t(B) and t(D); thus, postoperative pain severity appeared to be dependent on a central system controlling sensitivity to pain, linked to a POMC system releasing beta-lipotropin IRM into CSF and already active at times t(A) and t(B). We conclude that beta-lipotropin IRM in CSF might be considered to serve as a predictor of sensitivity to postoperative pain.