Medial Prefrontal Cortical Cannabinoid CB1 Receptors Mediate Morphine–Dextromethorphan Cross State-Dependent Memory: The Involvement of BDNF/cFOS Signaling Pathways

Pharmacotherapeutic value of inflammatory and neurotrophic biomarkers in bipolar disorder: A systematic review

BACKGROUND

The various pharmacological interventions, ranging from mood stabilizers and antipsychotics to antidepressants, reflect the diff/iculty of treating depressive/manic symptomatology of bipolar disorder (BD). Among a broad range of mechanisms implicated, immune dysregulation may contribute to the increased inflammation that influences the course of BD. Inflammatory, neurotrophic and oxidative stress factors may be identified as promising peripheral biomarkers in brain functioning, perhaps serving as predictors of an effective response to treatment for BD. The present systematic review aimed to examine the evidence supporting the pharmacotherapeutic value of inflammatory and neurotrophic biomarkers in BD.

METHODS

PubMed, PsychINFO, Scopus and Web of Science were searched from inception to May 2024 by two independent reviewers. A total of 40 studies with 3371 patients with diagnosis and intervention of BD were selected.

RESULTS

Inconsistencies in the effects of pharmacological treatments on the connection between the expected anti-inflammatory response and symptomatologic improvement were identified. Mood stabilizers (lithium), antipsychotics (quetiapine), antidepressants (ketamine) or their combination were described to increase both pro-inflammatory (TNFα, IL-6) and anti-inflammatory (IL-4, IL-8) factors. Other medications, such as memantine and dextromethorphan, autoimmune (infliximab) non-steroidal anti-inflammatory (aspirin, celecoxib) drugs, antidiabetics (pioglitazone), and even dietary supplementation (omega-3), or their combination, clearly decrease inflammatory factors (TNFα, IL-6, IL-1β, C-reactive protein) and/or increase the neurotrophic factor BDNF in BD patients.

CONCLUSION

Inflammation in BD requires further investigation to understand the underlying immunologic mechanism, to identify predictors of treatment response, and to make informed decisions about the use and development of more effective pharmacological interventions for BD.

Addictive drugs modify neurogenesis, synaptogenesis and synaptic plasticity to impair memory formation through neurotransmitter imbalances and signaling dysfunction

Drug abuse changes neurophysiological functions at multiple cellular and molecular levels in the addicted brain. Well-supported scientific evidence suggests that drugs negatively affect memory formation, decision-making and inhibition, and emotional and cognitive behaviors. The mesocorticolimbic brain regions are involved in reward-related learning and habitual drug-seeking/taking behaviors to develop physiological and psychological dependence on the drugs. This review highlights the importance of specific drug-induced chemical imbalances resulting in memory impairment through various neurotransmitter receptor-mediated signaling pathways. The mesocorticolimbic modifications in the expression levels of brain-derived neurotrophic factor (BDNF) and the cAMP-response element binding protein (CREB) impair reward-related memory formation following drug abuse. The contributions of protein kinases and microRNAs (miRNAs), along with the transcriptional and epigenetic regulation have also been considered in memory impairment underlying drug addiction. Overall, we integrate the research on various types of drug-induced memory impairment in distinguished brain regions and provide a comprehensive review with clinical implications addressing the upcoming studies.

Targeting mediodorsal thalamic CB1 receptors to inhibit dextromethorphan-induced anxiety/exploratory-related behaviors in rats: The post-weaning effect of exercise and enriched environment on adulthood anxiety

Dextromethorphan (DXM) is an effective over-the-counter antitussive with an alarming increase as an abused drug for recreational purposes. Although reports of the association between DXM administration and anxiety, there are few investigations into the underlying DMX mechanisms of anxiogenic action. Thus, the present study aimed to investigate the role of the mediodorsal thalamus (MD) cannabinoid CB1 receptors (CB1Rs) in DXM-induced anxiety/exploratory-related behaviors in adult male Wistar rats. Animals were bilaterally cannulated in the MD regions. After one week, anxiety and exploratory behaviors were measured using an elevated plus-maze task (EPM) and a hole-board apparatus. Results showed that DXM (3-7 mg/kg, i. p.) dose-dependently increased anxiety-like behaviors. Intra-MD administration of ACPA (2.5-10 ng/rat), a selective CB1 receptor agonist, decreased anxiety-like effects of DXM. The blockade of MD CB1 receptors by AM-251 (40-120 ng/rat) did not affect the EPM task. However, it potentiated the anxiogenic response of an ineffective dose of DXM (3 mg/kg) in the animals. Moreover, the effect of post-weaning treadmill exercise (TEX) and enriched environment (EE) were examined in adulthood anxiety under the drug treatments. Juvenile rats were divided into TEX/EE and control groups. The TEX/EE-juvenile rats were placed on a treadmill and then exposed to EE for five weeks. Interestingly, compared to untreated animals, post-weaning TEX/EE inhibited the anxiety induced by DXM or AM-251/DXM. It can be concluded that the MD endocannabinoid system plays an essential role in the anxiogenic effect of dextromethorphan. Moreover, post-weaning exercise alongside an enriched environment may have an inhibitory effect on adulthood anxiety-like behaviors.

Endocannabinoids and addiction memory: Relevance to methamphetamine/morphine abuse

AIM

This review aims to summarise the role of endocannabinoid system (ECS), incluing cannabinoid receptors and their endogenous lipid ligands in the modulation of methamphetamine (METH)/morphine-induced memory impairments.

METHODS

Here, we utilized the results from researches which have investigated regulatory role of ECS (including cannabinoid receptor agonists and antagonists) on METH/morphine-induced memory impairments.

RESULTS

Among the neurotransmitters, glutamate and dopamine seem to play a critical role in association with the ECS to heal the drug-induced memory damages. Also, the amygdala, hippocampus, and prefrontal cortex are three important brain regions that participate in both drug addiction and memory task processes, and endocannabinoid neurotransmission have been investigated.

CONCLUSION

ECS can be regarded as a treatment for the side effects of METH and morphine, and their memory-impairing effects.

Cross state-dependent memory retrieval between cannabinoid CB1 and serotonergic 5-HT1A receptor agonists in the mouse dorsal hippocampus

Understanding the neurobiological mechanisms of drug-related learning and memory formation may help the treatment of cognitive disorders. Dysfunction of the cannabinoid and serotonergic systems has been demonstrated in learning and memory disorders. The present paper investigates the phenomenon called state-dependent memory (SDM) induced by ACPA (a selective cannabinoid CB1 receptor agonist) and 8-OH-DPAT (a nonselective 5-HT1A receptor agonist) with special focus on the role of the 5-HT1A receptor in the effects of both ACPA and 8-OH-DPAT SDM and cross state-dependent memory retrieval between ACPA and 8-OH-DPAT in a step-down inhibitory avoidance task. The dorsal hippocampal CA1 regions of adult male NMRI mice were bilaterally cannulated, and all drugs were microinjected into the intended injection sites. A single-trial step-down inhibitory avoidance task was used to assess memory retrieval and state-dependence. Post-training and/or pre-test microinjections of ACPA (1 and 2 ng/mouse) and 8-OH-DPAT (0.5 and 1 μg/mouse) dose-dependently induced amnesia. Pre-test administration of the same doses of ACPA and 8-OH-DPAT reversed the post-training ACPA- and 8-OH-DPAT-induced amnesia, respectively. This phenomenon has been named SDM. 8-OH-DPAT (1 μg/mouse) reversed the amnesia induced by ACPA (0.5, 1, and 2 ng/mouse) and induced ACPA SDM. ACPA (2 ng/mouse) reversed the amnesia induced by 8-OH-DPAT (0.25, 0.5, and 1 μg/mouse) and induced 8-OH-DPAT SDM. Pre-test administration of a 5-HT1A receptor antagonist, (S)-WAY 100135 (0.25 and 0.5 μg/mouse), 5 min before ACPA and 8-OH-DPAT dose-dependently inhibited ACPA- and 8-OH-DPAT-induced SDM, respectively. The present study results demonstrated ACPA- and 8-OH-DPAT- induced SDM. Overall, the data revealed that dorsal hippocampal 5-HT1A receptor mechanisms play a pivotal role in modulating cross state-dependent memory retrieval between ACPA and 8-OH-DPAT.

Dual-specificity phosphatase 15 (DUSP15) in the nucleus accumbens is a novel negative regulator of morphine-associated contextual memory

Drug relapse among addicts often occurs due to the learned association between drug-paired cues and the rewarding effects of these drugs, such as morphine. Contextual memory associated with morphine has a central role in maintenance and relapse. We showed that morphine-conditioned place preference (CPP) activates extracellular-regulated protein kinase (ERK) in the nucleus accumbens (NAc). The main enzymes that mediate ERK dephosphorylation are members of the dual-specificity phosphatase (DUSP) superfamily. It is unclear which members regulate the morphine CPP-induced activation of ERK. After screening, DUSP15 was found to be decreased during both morphine CPP expression and the reinstatement period. Intra-NAc infusions of AAV-DUSP15 (overexpression) not only prevented the expression of morphine-induced CPP but also facilitated extinction, inhibited reinstatement, and abolished ERK activation. However, after repeated morphine exposure and withdrawal in mice, there was no change in the expression of p-ERK and DUSP15, and the overexpression of DUSP15 in the NAc did not improve the impaired spatial memory or anxiety-like behaviour induced by morphine. Together, these findings indicate that DUSP15 not only prevents the expression of drug-paired contextual memory but also promotes the extinction of existing addiction memories, thus providing a novel therapeutic target for the treatment of drug addiction.

Endogenous Opiates and Behavior: 2018

This paper is the forty-first consecutive installment of the annual anthological review of research concerning the endogenous opioid system, summarizing articles published during 2018 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides and receptors as well as effects of opioid/opiate agonists and antagonists. The review is subdivided into the following specific topics: molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors (2), the roles of these opioid peptides and receptors in pain and analgesia in animals (3) and humans (4), opioid-sensitive and opioid-insensitive effects of nonopioid analgesics (5), opioid peptide and receptor involvement in tolerance and dependence (6), stress and social status (7), learning and memory (8), eating and drinking (9), drug abuse and alcohol (10), sexual activity and hormones, pregnancy, development and endocrinology (11), mental illness and mood (12), seizures and neurologic disorders (13), electrical-related activity and neurophysiology (14), general activity and locomotion (15), gastrointestinal, renal and hepatic functions (16), cardiovascular responses (17), respiration and thermoregulation (18), and immunological responses (19).

Paternal morphine exposure induces bidirectional effects on cocaine versus opioid self-administration

The United States is in the midst of an opioid epidemic and is thus experiencing unprecedented levels of opioid exposure. A growing body of evidence has demonstrated that this may have consequences on multiple generations. The current set of experiments examined the effect of male adolescent opioid exposure on cocaine and opioid self-administration in the F1 generation. Male Sprague Dawley rats were administered increasing doses of morphine (5-25 mg/kg, s.c.) for 10 days during adolescence (P30-39). Rats were then maintained drug free until adulthood (P70-80) at which point they were mated with drug-naïve females. Male and female F1 offspring were first examined for cocaine self-administration during adulthood. Naïve littermates were tested for morphine self-administration acquisition followed by a within subjects design progressive ratio test for morphine, oxycodone, and cocaine. Results show that male and female F1 rats have delayed acquisition and decreased intake of cocaine. In addition, they have blunted PR levels compared to Sal-F1 control rats. Female Mor-F1 rats also demonstrate increased levels of morphine intake during acquisition and increased PR responding for oxycodone. Surprisingly, even following acquisition of morphine self-administration, Mor-F1 males and females still demonstrate blunted effort for cocaine. There were no differences in sucrose self-administration in naïve littermates. MorF0 seminiferous tubules demonstrated increased levels of acetylated histone H3 and there were increased levels of BDNF mRNA in the mPFC in male and female F1 offspring. Together, these data identify systems that are vulnerable to the impact of opioids in the F0 generation.

Cross state-dependent memory retrieval between morphine and norharmane in the mouse dorsal hippocampus

State-dependent memory (SDM) describes a phenomenon that memory is efficiently restored only when the brain state during restoration matches the state during encoding. Some psychoactive drugs such as morphine, ethanol, and cocaine evoke SDM. The scope of this study was to investigate the cross SDM between morphine and norharmane injected into the dorsal hippocampus of male NMRI mice, and the involvement of μ-opioid receptors (MORs) in the SDM of the drugs. Bilateral cannulae were implanted into the CA1 regions (intra-CA1), and memory retrieval was measured by the step-down apparatus. Results showed that pre-test microinjection of morphine (1 μg/mouse, intra-CA1) reversed amnesia induced by pre-training administration of the same dose of morphine, indicating morphine SDM. Moreover, norharmane (10 μg/mouse) also exerted a SDM. Pre-test microinjection of naloxone (0.5 μg/mouse) abolished amnesia induced by morphine or norharmane, and impaired SDM produced by each drug. The results demonstrated the contribution of MORs in the SDM induced by morphine as well as norharmane. Pre-test administration of morphine (1 μg/mouse, intra-CA1) also inhibited amnesia induced by pre-training intra-CA1 microinjection of norharmane (10 μg/mouse) and vice versa, suggesting a cross SDM between the drugs. In conclusion, it seems that there may be a cross SDM between morphine and norharmane, and MORs have a critical role in this phenomenon.