Effect of ceftriaxone and topiramate treatments on naltrexone-precipitated morphine withdrawal and glutamate receptor desensitization in the rat locus coeruleus

Effects of Beta Lactams on Behavioral Outcomes of Substance Use Disorders: A Meta-Analysis of Preclinical Studies

INTRODUCTION

Preclinical studies demonstrated that beta-lactams have neuroprotective effects in conditions involving glutamate neuroexcitotoxicity, including substance use disorders (SUDs). This meta-analysis aims to analyze the existing evidences on the effects of beta-lactams as glutamate transporter 1 (GLT-1) upregulators in animal models of SUDs, identification of gaps in the literature, and setting the stage for potential translation into clinical phases.

METHODS

Meta-analysis was conducted on preclinical studies retrieved systematically from MEDLINE and ScienceDirect databases. Abused substances were identified by refereeing to the National Institute on Drug Abuse (NIDA). The results were quantitatively described with a focus on the behavioral outcomes. Treatment effect sizes were described using standardized mean difference, and they were pooled using random effect model. I2-statistic was used to assess heterogeneity, and Funnel plot and Egger's test were used for assessment of publication bias.

RESULTS

Literature search yielded a total of 71 studies that were eligible to be included in the analysis. Through these studies, the effects of beta-lactams were evaluated in animal models of nicotine, cannabis, amphetamines, synthetic cathinone, opioids, ethanol, and cocaine use disorders as well as steroids-related aggressive behaviors. Meta-analysis showed that treatments with beta-lactams consistently reduced the pooled undesired effects of the abused substances in several paradigms, including drug-self administration, conditioned place preference, drug seeking behaviors, hyperlocomotion, withdrawal syndromes, tolerance to analgesic effects, hyperalgesia, and hyperthermia.

CONCLUSION

This meta-analysis revealed that enhancing GLT-1 expression in the brain through beta-lactams seemed to be a promising treatment approach in the context of substance use disorders, as indicated by results in animal models.

The effect of acute topiramate administration on morphine withdrawal syndrome and brain-derived neurotrophic factor in central nervous system

OBJECTIVES

Nucleus accumbens plays an important role in opioid addiction. Topiramate, increases postsynaptic gamma-aminobutyric acid receptor activity and antagonizes glutamatergic activity. Brain-derived neurotrophic factor (BDNF), which plays a key role in synaptic plasticity, is produced from proBDNF. The aim of this study is to investigate the effects of 100 µM topiramate applied into the lateral ventricle or nucleus accumbens on naloxone-induced morphine withdrawal and the BDNF/proBDNF ratio in the frontal cortex.

METHODS

In the study, 36 adult male Wistar rats weighing 250-350 g were used. Morphine dependence was created with morphine pellets following guide cannula implantations. Withdrawal findings were evaluated in naloxone-induced morphine withdrawal syndrome following topiramate administration, and locomotor activity measurements were performed simultaneously. The brains of sacrificed animals were removed for determination of BDNF/proBDNF ratio.

RESULTS

Topiramate administered by either route significantly suppressed the number of jumps in morphine withdrawal. Topiramate applied into the nucleus accumbens significantly reduced stereotypical behavior in morphine withdrawal, but did not cause any changes in other locomotor activity behaviors. Topiramate applied into the lateral ventricle significantly decreased the BDNF/proBDNF ratio, whereas administered into the nucleus accumbens significantly increased this ratio.

CONCLUSION

The findings of this study indicate that topiramate administered into the lateral ventricle and nucleus accumbens reduces naloxone-induced morphine withdrawal symptoms, stereotypical locomotor activity, and changes the BDNF/proBDNF ratio.

Metabotropic glutamate receptor function and regulation of sleep-wake cycles

Metabotropic glutamate (mGlu) receptors are the most abundant family of G-protein coupled receptors and are widely expressed throughout the central nervous system (CNS). Alterations in glutamate homeostasis, including dysregulations in mGlu receptor function, have been indicated as key contributors to multiple CNS disorders. Fluctuations in mGlu receptor expression and function also occur across diurnal sleep-wake cycles. Sleep disturbances including insomnia are frequently comorbid with neuropsychiatric, neurodevelopmental, and neurodegenerative conditions. These often precede behavioral symptoms and/or correlate with symptom severity and relapse. Chronic sleep disturbances may also be a consequence of primary symptom progression and can exacerbate neurodegeneration in disorders including Alzheimer's disease (AD). Thus, there is a bidirectional relationship between sleep disturbances and CNS disorders; disrupted sleep may serve as both a cause and a consequence of the disorder. Importantly, comorbid sleep disturbances are rarely a direct target of primary pharmacological treatments for neuropsychiatric disorders even though improving sleep can positively impact other symptom clusters. This chapter details known roles of mGlu receptor subtypes in both sleep-wake regulation and CNS disorders focusing on schizophrenia, major depressive disorder, post-traumatic stress disorder, AD, and substance use disorder (cocaine and opioid). In this chapter, preclinical electrophysiological, genetic, and pharmacological studies are described, and, when possible, human genetic, imaging, and post-mortem studies are also discussed. In addition to reviewing the important relationships between sleep, mGlu receptors, and CNS disorders, this chapter highlights the development of selective mGlu receptor ligands that hold promise for improving both primary symptoms and sleep disturbances.

Rapastinel accelerates loss of withdrawal signs after repeated morphine and blunts relapse to conditioned place preference

The purpose of the present study was to evaluate the efficacy of rapastinel, an allosteric modulator of NMDA receptor function, to accelerate the loss of opioid withdrawal symptoms and blunt or prevent relapse to morphine conditioned place preference (CPP) in rats. Two studies were conducted. In study 1, adult and adolescent male and female rats were treated with increasing doses of morphine (5 mg/kg, bid to 25 mg/kg bid) for 5 days. On day 6 animals were treated with naloxone (1 mg/kg) and withdrawal was assessed. They were then treated with saline or rapastinel (5 mg/kg) on days 6 and 8, and withdrawal was assessed on day 9. Rapastinel treated animals exhibited significantly lower levels of withdrawal signs on day 9. No sex or age differences were observed. In Study 2, CPP for morphine was established in adult rats (males and females) by 4 daily pairings with saline and morphine (am/pm alternation). They were tested for CPP on day 5, and then treated with rapastinel (5 mg/kg) or saline daily on days 6-10 of extinction. On day 11 they received a final dose of rapastinel or saline followed by extinction trial. On day 12, animals received 1 mg/kg of morphine and were tested for relapse. Rapastinel did not affect extinction of CPP, but rapastinel-treated animals spent significantly less time in the previously morphine-paired side than saline-treated animals during the relapse trial. These findings of accelerated loss of withdrawal signs and blunted relapse to CPP suggest that rapastinel could provide an adjunctive therapy for opioid dependence during initiation of pharmacotherapy for opioid dependence.

Non-Opioid Neurotransmitter Systems that Contribute to the Opioid Withdrawal Syndrome: A Review of Preclinical and Human Evidence

Opioid misuse and abuse is a major international public health issue. Opioid use disorder (OUD) is largely maintained by a desire to suppress aversive opioid withdrawal symptoms. Opioid withdrawal in patients seeking abstinence from illicit or prescribed opioids is often managed by provision of a μ-opioid agonist/partial agonist in combination with concomitant medications. Concomitant medications are administered based on their ability to treat specific symptoms rather than a mechanistic understanding of the opioid withdrawal syndrome; however, their use has not been statistically associated with improved treatment outcomes. Understanding the central and/or peripheral mechanisms that underlie individual withdrawal symptom expression in humans will help promote medication development for opioid withdrawal management. To support focused examination of mechanistically supported concomitant medications, this review summarizes evidence from preclinical (N = 68) and human (N = 30) studies that administered drugs acting on the dopamine, serotonin, cannabinoid, orexin/hypocretin, and glutamate systems and reported outcomes related to opioid withdrawal. These studies provide evidence that each of these systems contribute to opioid withdrawal severity. The Food and Drug Administration has approved medications acting on these respective systems for other indications and research in this area could support the repurposing of these medications to enhance opioid withdrawal treatment. These data support a focused examination of mechanistically informed concomitant medications to help reduce opioid withdrawal severity and enhance the continuum of care available for persons with OUD.

Sex differences in morphine-induced trafficking of mu-opioid and corticotropin-releasing factor receptors in locus coeruleus neurons

The locus coeruleus (LC)-norepinephrine (NE) system is a key nucleus in which endogenous opioid and stress systems intersect to regulate the stress response. LC neurons of male rats become sensitized to stress following chronic morphine administration. Whether sex dictates this pattern of opioid-induced plasticity has not been demonstrated. Delineating the neurobiological adaptations produced by chronic opioids will enhance our understanding of stress vulnerability in opioid-dependent individuals, and may reveal how stress negatively impacts addiction recovery. In the present study, the effect of chronic morphine on the subcellular distribution of mu-opioid (MOR) and CRF receptors (CRFR) was investigated in the LC of male and female rats using immunoelectron microscopy. Results showed that placebo-treated females exhibited higher MOR and CRFR cytoplasmic distribution ratio when compared to placebo-treated males. Chronic morphine exposure induced a shift in the distribution of MOR immunogold-silver particles from the plasma membrane to the cytoplasm selectively in male LC neurons. Interestingly, chronic morphine exposure induced CRFR recruitment to the plasma membrane of both male and female LC neurons. These findings provide a potential mechanism by which chronic opioid administration increases stress vulnerability in males and females via an increase in surface availability of CRFR in LC neurons. However, our results also support the notion that cellular adaptations to chronic opioids differ across the sexes as redistribution of MOR following morphine exposure was only observed in male LC neurons.

Variability in prescription opioid intake and reinforcement amongst 129 substrains

Opioid abuse in the United States has reached epidemic proportions, with treatment admissions and deaths associated with prescription opioid abuse quadrupling over the past 10 years. Although genetics are theorized to contribute substantially to inter-individual variability in the development, severity and treatment outcomes of opioid abuse/addiction, little direct preclinical study has focused on the behavioral genetics of prescription opioid reinforcement and drug-taking. Herein, we employed different 129 substrains of mice currently available from The Jackson Laboratory (129S1/SvlmJ, 129X1/SvJ, 129S4/SvJaeJ and 129P3/J) as a model system of genetic variation and assayed mice for oral opioid intake and reinforcement, as well as behavioral and somatic signs of dependence. All substrains exhibited a dose-dependent increase in oral oxycodone and heroin preference and intake under limited-access procedures and all, but 129S1/SvlmJ mice, exhibited oxycodone reinforcement. Relative to the other substrains, 129P3/J mice exhibited higher heroin and oxycodone intake. While 129X1/SvJ exhibited the highest anxiety-like behavior during natural opioid withdrawal, somatic and behavior signs of precipitated withdrawal were most robust in 129P3/J mice. These results demonstrate the feasibility and relative sensitivity of our oral opioid self-administration procedures for detecting substrain differences in drug reinforcement/intake among 129 mice, of relevance to the identification of genetic variants contributing to high vs. low oxycodone reinforcement and intake.

Endogenous Opiates and Behavior: 2015

This paper is the thirty-eighth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2015 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.

Nephroprotective efficacy of ceftriaxone against cisplatin-induced subchronic renal fibrosis in rats

Cisplatin, or cis-diamminedichloridoplatinum(II), (CDDP) is a broad-spectrum antineoplastic chemotherapeutic agent with a potent efficacy against several malignancies. Its main clinical antineoplastic therapy-limiting adverse effect is nephrotoxicity, where the developments of effective nephroprotectors are needed. Therefore, the present study aimed to investigate the nephroprotective and antifibrotic potential of ceftriaxone (CTX) against CDDP-induced toxicity. Male Wister rats were treated with saline or CTX (100 or 200 mg kg^-1 bw) an hour before CDDP administration (1 mg kg^-1 bw). All the treatments were intraperitoneally administered twice weekly for consecutive 10 weeks. Twenty-four hours after last CDDP dose, blood samples were collected, then the animals were euthanized and their kidneys were isolated for measurements. CDDP significantly increased serum uric acid, urea, and creatinine contents. Toxicopathic changes showed that CDDP induced marked tubulointerstitial damage, overexpressed fibrogenic factors α-smooth muscle actin (α-SMA) and transforming growth factor-β1 (TGF-β1), and down expressed cellular proliferating biomarker bromodeoxyuridine (BrdU). CTX pretreatment, particularly 200 mg/kg bw, improved the renal function biomarkers; histoarchitecture; and α-SMA, TGF-β1, and BrdU expressions. It could be concluded that CTX is endowed with antifibrotic properties and could be, therefore, used as adjuvant therapy to improve CDDP-induced nephrotoxicity. Further clinical researches are necessary to evaluate whether CTX may exhibit a new therapeutic choice for treating renal fibrotic diseases.

Role of astrocytic glutamate transporter in alcohol use disorder

Alcohol use disorder (AUD) is one of the most widespread neuropsychiatric conditions, having a significant health and socioeconomic impact. According to the 2014 World Health Organization global status report on alcohol and health, the harmful use of alcohol is responsible for 5.9% of all deaths worldwide. Additionally, 5.1% of the global burden of disease and injury is ascribed to alcohol (measured in disability adjusted life years, or disability adjusted life years). Although the neurobiological basis of AUD is highly complex, the corticostriatal circuit contributes significantly to the development of addictive behaviors. In-depth investigation into the changes of the neurotransmitters in this circuit, dopamine, gamma-aminobutyricacid, and glutamate, and their corresponding neuronal receptors in AUD and other addictions enable us to understand the molecular basis of AUD. However, these discoveries have also revealed a dearth of knowledge regarding contributions from non-neuronal sources. Astrocytes, though intimately involved in synaptic function, had until recently been noticeably overlooked in their potential role in AUD. One major function of the astrocyte is protecting neurons from excitotoxicity by removing glutamate from the synapse via excitatory amino acid transporter type 2. The importance of this key transporter in addiction, as well as ethanol withdrawal, has recently become evident, though its regulation is still under investigation. Historically, pharmacotherapy for AUD has been focused on altering the activity of neuronal glutamate receptors. However, recent clinical evidence has supported the animal-based findings, showing that regulating glutamate homeostasis contributes to successful management of recovery from AUD.