Biotransformation of beta-endorphin and possible therapeutic implications

Evaluation of the Influence of Biological Factors during the Course of Treatment in Patients with Ovarian Cancer

The aim of this study was to evaluate the influence of β-endorphins and serotonin on the course of treatment, disease-free time, and overall survival of patients with ovarian cancer. This study may contribute to the identification of modifiable factors that may influence the treatment of ovarian cancer. The research was carried out in a group of 162 patients of which 139 respondents were included in the research; ovarian cancer was diagnosed in 78 of these patients. The study consisted of three stages. In the first stage of diagnostics, a survey among the patients was carried out. In the second stage-5 mL of blood was collected from each patient (n = 139) in the preoperative period to determine the concentration of β-endorphin and serotonin. In the third stage-blood samples were collected from those patients who had completed chemotherapy treatment or had surgery. Concentrations of β-endorphin and serotonin were measured by the Luminex method, using the commercial Luminex Human Discovery Assay kit. The average age of the patients was 62.99 years. The level of β-endorphin significantly differs among patients diagnosed with ovarian cancer and among patients in the control group (202.86; SD-15.78 vs. 302.00; SD-24.49). A lower level of β-endorphins was found in the patients with a recurrence of the neoplastic process compared to those without recurrence (178.84; SD-12.98 vs. 205.66; SD-13.37). On the other hand, the level of serotonin before chemotherapy was higher in the group of people with disease recurrence compared to those without recurrence (141.53; SD-15.33 vs. 134.99; SD-10.08). Statistically significantly positive correlations were found between the level of β-endorphin and both disease-free time (β-endorphin levels before chemotherapy: rho Spearman 0.379, p < 0.027; β-endorphin levels after chemotherapy: rho Spearman 0.734 p < 0.001) and survival time (β-endorphin levels before chemotherapy: rho Spearman 0.267, p < 0.018; β-endorphin levels after chemotherapy: rho Spearman 0.654 p < 0.001). 1. The levels of serotonin and β-endorphin levels are significantly related to ovarian cancer and change during treatment. 2. High mean preoperative concentrations of β-endorphins were significantly related to overall survival and disease-free time.

Endogenous Opioid Levels Do Not Correlate With Itch Intensity and Therapeutic Interventions in Hepatic Pruritus

Background: Chronic pruritus affects up to 70% of patients with immune-mediated hepatobiliary disorders. Antagonists of the μ-opioid receptor (MOR) and agonists of the κ-opioid receptor (KOR) are used to treat hepatic itch, albeit with limited success. An imbalance between ligands of MOR and KOR receptors has recently been suggested as a potential mechanism of hepatic pruritus. In this study, we therefore investigated systemic levels of important endogenous opioids such as β-endorphin, dynorphin A, Leu- and Met-enkephalin in plasma of a large cohort of well-characterized patients with immune-mediated cholestatic disorders, including patients with liver cirrhosis, and during effective anti-pruritic therapy.

Methods: Plasma samples and clinical data were prospectively collected from well-characterized patients with primary/secondary sclerosing cholangitis (PSC/SSC), primary biliary cholangitis (PBC) and overlap syndromes suffering from pruritus (n = 29) and age-, gender- and disease-matched controls without pruritus (n = 27) as well as healthy controls (n = 20). General laboratory testing for hepatobiliary and renal function was performed. Levels of β-endorphin, dynorphin A, Leu- and Met-enkephalin were quantified in plasma by ELISA. Intensity of pruritus over the last week was evaluated using a visual analog scale (VAS, 0–10).

Results: PBC and PSC patients with or without pruritus did neither differ in disease entity, disease stage, nor in the presence of cirrhosis. While both dynorphin A and β-endorphin concentrations were lower in pruritic patients compared to those without pruritus and healthy controls, the MOR/KOR ligand ratio was unaltered. No significant differences were observed for Leu- and Met-enkephalin concentrations. Opioid levels correlated with neither itch intensity nor stage of disease. Cirrhotic patients displayed higher concentrations of MOR agonist Leu-enkephalin and KOR agonist dynorphin A. Endogenous opioid levels remained largely unchanged after successful treatment with the potent anti-pruritic drugs rifampicin and bezafibrate.

Conclusions: Endogenous opioid levels and the MOR/KOR ligand ratio neither correlate with itch intensity nor differentiate pruritic from non-pruritic patients with immune-mediated liver diseases. Thus, endogenous opioids may modulate signaling pathways involved in hepatic pruritus, but are unlikely to represent the major pruritogens in liver disease.

Neprilysin inhibition, endorphin dynamics, and early symptomatic improvement in heart failure: a pilot study

Aim

Sacubitril/valsartan is a first‐in‐class angiotensin receptor‐neprilysin inhibitor developed for the treatment of heart failure with reduced ejection fraction. Its benefits are achieved through the inhibition of neprilysin (NEP) and the specific blockade of the angiotensin receptor AT1. The many peptides metabolized by NEP suggest multifaceted potential consequences of its inhibition. We sought to evaluate the short‐term changes in serum endorphin (EP) values and their relation with patients' physical functioning after initiation of sacubitril/valsartan treatment.

Methods and results

A total of 105 patients with heart failure with reduced ejection fraction, who were candidates for sacubitril/valsartan treatment, were included in this prospective, observational, multicentre, and international study. In a first visit, and in agreement with current guidelines, treatment with angiotensin‐converting enzyme inhibitors or angiotensin receptor blocker was replaced by sacubitril/valsartan because of clinical indication by the responsible physician. By protocol, patients were reevaluated at 30 days after the start of sacubitril/valsartan. Serum levels of α‐ (α‐EP), γ‐Endorphin (γ‐EP), and soluble NEP (sNEP) were measured using enzyme‐linked immunoassays. New York Heart Association (NYHA) functional class was used as an indicator of patient's functional status. Baseline median levels of circulating α‐EP, γ‐EP, and sNEP were 582 (160–772), 101 (37–287), and 222 pg/mL (124–820), respectively. There was not a significant increase in α‐EP nor γ‐EP serum values after sacubitril/valsartan treatment (P value = 0.194 and 0.102, respectively). There were no significant differences in sNEP values between 30 days and baseline (P value = 0.103). Medians (IQR) of Δα‐EP, Δγ‐EP, and ΔsNEP between 30 days and baseline were 9.3 (−34 − 44), −3.0 (−46.0 − 18.9), and 0 units (−16.4 − 157.0), respectively. In a pre–post sacubitril/valsartan treatment comparison, there was a significant improvement in NYHA class, with 36 (34.3%) patients experiencing improvement by at least one NYHA class category. Δα‐EP and ΔsNEP showed to be significantly associated with NYHA class after 30 days of treatment (P = 0.014 and P < 0.001, respectively). Δα‐EP was linear and significantly associated with NYHA class improvement after 30 days of sacubitril/valsartan treatment.

Conclusions

These preliminary data suggest that beyond the haemodynamic benefits achieved with sacubitril/valsartan, the altered cleavage of endorphin peptides by NEP inhibition may participate in patients' symptoms improvement.

Dynamic measurement of extracellular opioid activity: status quo, challenges, and significance in rewarded behaviors

Opioid peptides are the endogenous ligands of opioid receptors, which are also the molecular target of naturally occurring and synthetic opiates, such as morphine and heroin. Since their discovery in the 1970s, opioid peptides, which are found widely throughout the central nervous system and the periphery, have been intensely studied because of their involvement in pain and pleasure. Over the years, our understanding of opioid peptides has widened to cover a multitude of functions, including learning and memory, affective state, gastrointestinal transit, feeding, immune function, and metabolism. Unsurprisingly, aberrant opioid activity is implicated in numerous pathologies, including drug addiction, overeating, pain, depression, and obesity. To date, virtually all preclinical and clinical studies aimed at understanding the function of endogenous opioids have relied upon manipulating endogenous opioid fluxes using opioid receptor ligands or genetic manipulations of opioid receptors and endogenous opioids. Difficulties in directly monitoring endogenous opioid fluxes, particularly in the central nervous system, have presented a major obstacle to fully understanding endogenous opioid function. This review summarizes these challenges and offers suggestions for future goals while focusing on the neurobiology of reward, specifically drawing attention to studies that have succeeded in dynamically measuring opioid peptides.