Chronic exposure to the opioid growth factor, [Met5]-enkephalin, during pregnancy: maternal and preweaning effects

Methionine enkephalin activates autophagy and stimulates tumour cell immunogenicity in human cutaneous squamous cell carcinoma

Cutaneous squamous cell carcinoma (CSCC) is a common skin tumour. Due to weak immunogenicity, recurrence is frequent after treatment. In this study, we explored the effects and mechanisms of methionine enkephalin (MENK), an endogenous opioid peptide and negative growth regulator, in CSCC. MENK inhibited A431 cell proliferation and promoted apoptosis through the opioid growth factor receptor (OGFr). Importantly, MENK also induced autophagy in CSCC and stimulated the emission of DAMPs in A431 cells, which resulted in enhanced activation of dendritic cells (DC).In conclusion, MENK provides an effective method with therapeutic potential to modulate the CSCC microenvironment by utilizing autophagy in the cancer cells.

Developmental opioid exposures: Neurobiological underpinnings, behavioral impacts, and policy implications

The devastating impact of opioid abuse and dependence on the individual, family, and society are well known but extremely difficult to combat. During pregnancy, opioid drugs and withdrawal also affect fetal brain development and newborn neural functions, in addition to maternal effects. Neonatal Abstinence Syndrome/Neonatal Opioid Withdrawal Syndrome (NAS/NOWS) rates have drastically increased in the US in the past decade. Solutions to this complex problem must be multi-faceted, which would be greatly enhanced by a translational, multidisciplinary understanding. Therefore, this mini-review incorporates biomedical, clinical, and policy aspects of opioid use during pregnancy. We review the known roles for endogenous opioids in mediating circuit formation and function in the developing brain, discuss how exogenous opioid drug use and addiction impact these processes in animal models and humans, and discuss the implications of these data on public policy. We suggest that some current policy initiatives produce unintended harm on both mothers and their children and delineate recommendations for how legislation could better contribute to addiction recovery and increase neural resilience in affected children.

Impact statement

Opioid abuse is a critical epidemic affecting individuals, families, and communities. This mini-review summarizes current literature on the impact of opioid drugs—including prescription pain relievers and illicit opioids—on neurobiological and neurobehavioral development. Using concepts related to the medical model of addiction as a brain disease, we review the public policy implications of these data and identify needs for future investigations.

Prospective oncotarget for gynecological cancer: Opioid growth factor (OGF) - opioid growth factor receptor (OGFr) axis

The standard treatments for neoplasia include surgery, chemotherapy, hormone antagonists and radiotherapy, which can prolong survival, but rarely cure the tumors of gynecological cancer patients. OGF - OGFr expression, in various gynecologic cells and tissues, is an intersection point between cell development, neuroendocrine function and immune modulation. It has been identified that OGF and OGFr expression differs between gynecological tumor and normal cells. Further, exogenous or endogenous OGF and OGFr antagonists have been known to have a role in regulating cell viability and apoptosis. Moreover, the expression of proteins in the OGF - OGFr axis modulate differentiation and membrane expression of immune cells, which can enhance the immune response. In vivo and in vitro assays have shown that OGF and OGFr antagonists inhibit mitosis as well as induce apoptosis in gynecologic cancer cells. Although immune augmentation combination therapies can intensify cytotoxic activity, OGF or OGFr antagonists do not increase toxicities associated with dual-immune regulation. In conclusion, the OGF - OGFr axis provides significant strategies for antitumor efficiency in gynecological cancer.

Opioid Drug Use and Acute Cardiac Events Among Pregnant Women in the United States

BACKGROUND

Cardiovascular disease remains a leading cause of pregnancy-associated deaths in the United States. The extent to which increasing opioid use among pregnant women contributes to fatal cardiovascular events is unknown. We examined trends in opioid use among pregnant women over the previous decade and the association between changes in temporal trends in opioid drug use and the incidence of acute cardiac events among mothers.

METHODS

In this retrospective analysis of the Healthcare and Cost Utilization Project, we used a 2-stage stratified cluster sampling of all inpatient hospital discharges from nonfederal hospitals from January 1, 2002 through December 31, 2014. The study population comprised pregnant women aged 13-49 years and related hospitalizations, including delivery. The primary exposure of interest was opioid use during pregnancy. The primary outcome was the occurrence of acute myocardial infarction or cardiac arrest during pregnancy or childbirth.

RESULTS

Among the estimated 57.4 million pregnancy-related inpatient hospitalizations, 511,469 (approximately 1%) had documented use of opioids, cocaine, and/or amphetamines. There was a 300% increase in the use of opioids during pregnancy over the study period, whereas cocaine consumption significantly decreased and that of amphetamine remained stable. Over the 13-year period, the rise in opioid use paralleled a 50% increase in the incidence of acute cardiac events among mothers.

CONCLUSION

Over the previous decade opioid use during pregnancy increased significantly, in parallel with the rise in the incidence of acute cardiac events in pregnancy and childbirth. An effective national policy is needed to address this emerging public health challenge.

Spatiotemporal expression of endogenous opioid processing enzymes in mouse uterus at peri-implantation

Successful implantation requires intimate interactions between a competent blastocyst and a receptive uterus. We recently demonstrated that the aberrant activation of opioid signaling by exogenous ligands adversely affects preimplantation embryonic development and subsequent implantation in mice. However, the underlying machinery governing the dynamic homeostasis of the endogenous opioid system in the uterus during early pregnancy remains elusive. We now show that all three major endogenous opioid precursors are spatiotemporally expressed in the uterus during early pregnancy. Moreover, we observe the well-coordinated expression of the synthetic enzyme prohormone convertases 1/3 (PC1/3) at lower levels and of its inhibitor proprotein convertase subtilisin/kexin type 1 inhibitor (Pcsk1n) and the degrading enzyme membrane metallo-endopeptidase (MME) at higher levels in the receptive uterus. Both estrogen and progestin tend to reduce the uterine levels of opioid ligand precursors in the ovariectomized mouse model. This tight regulation of the endogenous opioid system by PC1/3, Pcsk1n and MME has been further confirmed in physiologically related pseudopregnancy and delayed implantation mouse models. The coordinated regulation of opioid precursor biosynthesis and metabolism helps to create appropriate opioid signaling ensuring uterine receptivity for implantation. Thus, endogenous uterine opioid levels are primarily determined by the coordinated expressions of PC1/3, Pcsk1n and MME under the influence of ovarian progestin and estrogen. Our findings raise an additional cautionary note regarding the effects of opioid abuse on early pregnancy events.

Increasing pregnancy-related use of prescribed opioid analgesics

PURPOSE

To quantify the prevalence of prescribed opioid analgesics among pregnant women enrolled in Tennessee Medicaid from 1995 to 2009.

METHODS

Retrospective cohort study of 277,555 pregnancies identified from birth and fetal death certificates, and linked to previously validated, computerized pharmacy records. Poisson regression was used to estimate trends over time, rate ratios, and 95% confidence intervals (CI).

RESULTS

During the study period, 29% of pregnant women filled a prescription for an opioid analgesic. From 1995 to 2009, any pregnancy-related use increased 1.90-fold (95% CI, 1.83-1.98), first trimester use increased 2.27-fold (95% CI, 2.14-2.41), and second or third trimester use increased 2.02-fold (95% CI, 1.93-2.12), after adjusting for maternal characteristics. Any pregnancy-related, first trimester, and second or third trimester use were each more likely among mothers who were at least 21 years old, white, non-Hispanic, prima gravid, resided in nonurban areas, enrolled in Medicaid owing to disability, and who had less than a high school education.

CONCLUSIONS

Opioid analgesic use by Tennessee Medicaid-insured pregnant women increased nearly 2-fold from 1995 to 2009. Additional study is warranted to understand the implications of this increased use.

Naltrexone in the treatment of opioid-dependent pregnant women: the case for a considered and measured approach to research

The present paper considers naltrexone to treat opioid dependence during pregnancy. The public health problem of opioid dependence and its treatment during pregnancy is reviewed first. Next, the naltrexone and opioid dependence treatment literature is summarized, with overviews of the pre-clinical and clinical research on prenatal naltrexone exposure. Finally, considerations and recommendations for future medication research for the treatment of opioid dependence in pregnant women are provided. The efficacy of long-acting injectable naltrexone relative to placebo, its blockade of opioid agonist euphoric effects, its lack of abuse and tolerance development and its modest adverse effect profile make it a potential medication for opioid-dependent pregnant women. However, it is not without seriously concerning potential drawbacks, including the difficulty surrounding medication induction that may lead to vulnerability with regard to relapse, physical dependence re-establishment, increased risk behaviors, treatment dropout and resulting opioid overdose. Before embarking on future research with this medication, the benefits and risks for the mother-embryo/fetus/child dyad should be weighed carefully. Should future research be conducted, a multi-level commitment to proactive ethical research is needed to reach the ultimate goal of improving the lives of women and children affected by opioid dependence.

κ-Opioid receptor stimulation inhibits growth of neonatal rat ventricular myocytes

The effects of trans-(+/-)-3,4-dichloro-N-methyl-N-[2-(1-pyrrolidinyl)-cyclohexyl]-benzeneacetamide methanesulfonate salt (U50,488H), a selective kappa-opioid receptor agonist, on growth in neonatal ventricular myocytes were determined. In 15% serum culture medium, U50,488H at 0.1-1 microM significantly reduced the protein content, [3H]leucine uptake and cell size of the myocytes. The effect of U50,488H on protein content was abolished in the presence of 1 microM nor-binaltorphimine (nor-BNI), a selective kappa-opioid receptor antagonist. In a 0.4% serum medium, U50,488H at 0.1-1 microM had no effect on myocyte growth. Interestingly, 1 microM U50,488H abolished the stimulatory effects of 1 microM norepinephrine on protein content, [3H]leucine uptake and cell size of the myocytes in the low serum medium. The effect of U50,488H was abolished by 1 microM nor-BNI. With the exception of cell size, the effects of norepinephrine were completely abolished by blockade of both alpha- and beta-adrenoceptors, but only partially blocked by blockade of either adrenoceptors. These results provide first evidence that kappa-opioid receptor stimulation inhibits growth of the neonatal ventricular myocyte as a result of direct action as well as by inhibiting sympathetic stimulation of the heart. The stimulatory effects of sympathetic activity on growth occurs via both alpha- and beta-adrenoceptors.

Gene expression of OGFr in the developing and adult rat brain and cerebellum

The native opioid peptide, [Met5]-enkephalin (termed opioid growth factor (OGF)), is a tonically active negative growth factor targeted to cell proliferation in the developing nervous system. OGF action is mediated by the OGF receptor (OGFr). The present study investigates gene expression of OGFr in the developing and adult brain and cerebellum of the rat using Northern blot analysis and normalization to GAPDH. OGFr was detected in whole brain at embryonic day 20 and birth, and was at least twofold greater than neonatal levels during the first week of life. From postnatal day 15 onwards to adulthood, levels of OGFr mRNA in the whole brain were detectable but less than those at birth. OGFr mRNA in cerebellum was found on embryonic day 20, and remained relatively constant until postnatal day 12 when a sharp increase was recorded. In the third week of life and continuing into adulthood, cerebellar OGFr mRNA was detected at levels comparable to those in postnatal week 1. These results show that message for OGFr is developmentally regulated prior to and after birth, is ubiquitously expressed during development, and is present in the adult brain and cerebellum even though OGF receptor binding is not recorded.

Endogenous opiates and behavior: 2002

This paper is the twenty-fifth consecutive installment of the annual review of research concerning the endogenous opioid system, now spanning over a quarter-century of research. It summarizes papers published during 2002 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 neurologic 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).