Species differences in the effects of the κ-opioid receptor antagonist zyklophin

Enhancement of a Heroin Vaccine through Hapten Deuteration

The United States is in the midst of an unprecedented epidemic of opioid substance use disorder, and while pharmacotherapies including opioid agonists and antagonists have shown success, they can be inadequate and frequently result in high recidivism. With these challenges facing opioid use disorder treatments immunopharmacotherapy is being explored as an alternative therapy option and is based upon antibody-opioid sequestering to block brain entry. Development of a heroin vaccine has become a major research focal point; however, producing an efficient vaccine against heroin has been particularly challenging because of the need to generate not only a potent immune response but one against heroin and its multiple psychoactive molecules. In this study, we explored the consequence of regioselective deuteration of a heroin hapten and its impact upon the immune response against heroin and its psychoactive metabolites. Deuterium (H_dAc) and cognate protium heroin (H_Ac) haptens were compared head to head in an inclusive vaccine study. Strikingly the H_dAc vaccine granted greater efficacy in blunting heroin analgesia in murine behavioral models compared to the H_Ac vaccine. Binding studies confirmed that the H_dAc vaccine elicited both greater quantities and equivalent or higher affinity antibodies toward heroin and 6-AM. Blood-brain biodistribution experiments corroborated these affinity tests. These findings suggest that regioselective hapten deuteration could be useful for the resurrection of previous drug of abuse vaccines that have met limited success in the past.

New concepts in opioid analgesia

INTRODUCTION

Opioids are the oldest and most potent drugs for the treatment of severe pain, but they are burdened by detrimental side effects such as respiratory depression, addiction, sedation, nausea, and constipation. Their clinical application is undisputed in acute (e.g. perioperative) and cancer pain, but their long-term use in chronic pain has met increasing scrutiny and has contributed to the current 'opioid crisis.'

AREAS COVERED

This article reviews pharmacological principles and research strategies aiming at novel opioids with reduced side effects. Basic mechanisms underlying pain, opioid analgesia, and other opioid actions are outlined. To illustrate the clinical situation and medical needs, plasticity of opioid receptors, intracellular signaling pathways, endogenous and exogenous opioid receptor ligands, central and peripheral sites of analgesic, and side effects are discussed.

EXPERT OPINION

The epidemic of opioid misuse has taught us that there is a lack of fundamental knowledge about the characteristics and management of chronic pain, that conflicts of interest and validity of models must be considered in the context of drug development, and that novel analgesics with less abuse liability are badly needed. Currently, the most promising perspectives appear to be augmenting endogenous opioid actions and selectively targeting pathological conformations of peripheral opioid receptors.

Involvement of Activated Brain Stress Responsive Systems in Excessive and "Relapse" Alcohol Drinking in Rodent Models: Implications for Therapeutics

Addictive diseases, including addiction to alcohol, pose massive public health costs. Addiction is a chronic relapsing disease caused by both the direct effects induced by drugs and persistent neuroadaptations at the molecular, cellular, and behavioral levels. These drug-type specific neuroadaptations are brought on largely by the reinforcing effects of drugs on the central nervous system and environmental stressors. Results from animal experiments have demonstrated important interactions between alcohol and stress-responsive systems. Addiction to specific drugs such as alcohol, psychostimulants, and opioids shares some common direct or downstream effects on the brain's stress-responsive systems, including arginine vasopressin and its V1b receptors, dynorphin and the κ-opioid receptors, pro-opiomelanocortin/β-endorphin and the μ-opioid receptors, and the endocannabinoids. Further study of these systems through laboratory-based and translational research could lead to the discovery of novel treatment targets and the early optimization of interventions (for example, combination) for the pharmacologic therapy of alcoholism.

Endogenous Opiates and Behavior: 2016

This paper is the thirty-ninth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2016 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, and the roles of these opioid peptides and receptors in pain and analgesia, stress and social status, tolerance and dependence, learning and memory, eating and drinking, drug abuse and alcohol, sexual activity and hormones, pregnancy, development and endocrinology, mental illness and mood, seizures and neurologic disorders, electrical-related activity and neurophysiology, general activity and locomotion, gastrointestinal, renal and hepatic functions, cardiovascular responses, respiration and thermoregulation, and immunological responses.

Antagonism of the kappa opioid receptor attenuates THC-induced place aversions in adult male Sprague-Dawley rats

RATIONALE

Prior research with transgenic mice in which the kappa opioid receptor (KOR) has been suppressed or activated suggests that the aversive effects of THC are mediated by activity of this receptor subtype. If the activity of the KOR system is responsible for mediating the THC's aversive effects, then selective antagonism of the KOR by norBNI should block such aversive effects. To test this hypothesis, rats were pretreated with norBNI 24h prior to place conditioning with THC to assess its effect on the acquisition of THC-induced place aversions.

METHODS

In Experiment 1, rats pretreated with norBNI (0 or 15mg/kg) were exposed 24h later to one side of a place conditioning chamber and injected with THC (0, 0.56, 1 and 3.2mg/kg). On the next day, they were injected with vehicle and placed on the opposite side of the chamber. This was repeated for a total of five cycles followed by a test of the animal's aversion to the THC-paired side. In Experiment 2, rats were pretreated with norBNI (0 or 30mg/kg) prior to place conditioning 24h later with THC (0 or 3.2mg/kg).

RESULTS

In Experiment 1, THC produced dose-dependent place aversions that were unaffected by norBNI (15mg/kg). In Experiment 2, THC induced significant place aversions that were fully attenuated by norBNI (30mg/kg).

CONCLUSIONS

Although 15mg/kg norBNI was ineffective in antagonizing the aversive effects of THC, 30mg/kg norBNI blocked the ability of THC to induce a place aversion. The results of the latter assessment are consistent with prior research with transgenic manipulations of the KOR and provide further evidence for the role of the KOR system in the aversive properties of THC.