Mitragynine Attenuates Morphine Withdrawal Effects in Rats-A Comparison With Methadone and Buprenorphine

Exploring the cognitive effects of kratom: A review

Despite the strict kratom regulation in some regions, the demand for kratom products is still increasing worldwide. Kratom products are commonly consumed for their pain-relieving effect or as a self-treatment for opioid use disorder. Kratom is also taken as a recreational drug among youth and adults. Since substance abuse can cause cognitive impairment, many studies investigated the effects of kratom on cognition. The interaction of some kratom alkaloids with various receptors such as opioid, serotonergic, and adrenergic receptors further sparks the interest to investigate the effects of kratom on cognitive function. Hence, this review aims to provide an overview of the effects of kratom on cognitive behaviours and their underlying changes in neurobiological mechanisms. In conclusion, kratom, particularly its main alkaloid, mitragynine may adversely affect cognitive performances that may be attributed to the disruption in synaptic plasticity, brain activity as well as various proteins involved in synaptic transmission. The impact of kratom on cognitive functions could also shed light on its safety profile, which is essential for the therapeutic development of kratom, including its potential use in opioid substitution therapy.

Discovery of rhynchophylline and mitraphylline in two Thai Mitragyna species and the investigation of their biological activity via opioid gene expression analysis

Mitragyna speciosa (Ms), M. diversifolia (Md), M. hirsuta (Mh) and M. rotundifolia (Mr) were investigated for phytochemicals by GC-MS and GC-FID, cytotoxicity and genotoxicity testing by MTT and comet assay, and biological activity examination through gene expression of human µ, δ, κ, and nociceptin opioid receptors by qRT-PCR. The opioid substances mitragynine, 7-hydroxymitragynine, and mitraphylline were found in all studied species, and, for first time, rhynchophylline was found in Mr, and mitraphylline in Md, Mh and Mr. The MTT and comet assays of the ethanol and hexane leaf extracts on PBMCs revealed no cytotoxicity and no significant genotoxicity compared to the negative control, except for the hexane leaf extract of Mh, which caused significant DNA damage. The biological activity of the ethanolic extract of the four species showed a binding affinity to the µ (MOR) receptor revealing a relative gene expression of 89.54 and 50.41 by Ms and Md at 1.92 and 1.133 mg/ml, 32.42 and 19.97 mg/ml by Md and Ms at 3.77 and 1.76 mg/ml. Mr contained the three opioids mentioned plus rhynchophylline and showed low relative µ (MOR) gene expression of 16.89 at 0.189 mg/ml, while as an additional species, Ipomoea aquatica (Ia) showed higher relative µ (MOR) gene expression of 37.75 and 59.76 at 2.878, and 5.813 mg/ml. A combination of Mr and Ia at 1.227, 2.907 and 0.0123, 0.0291 mg/ml extract showed high relative µ (MOR) gene expression at 71.01 and 21.71. These Mitragyna species and the combination (formula details are patent registered), substances and their biological activities can be used for the innovative production of new medicines and further clinical investigation.

Aggression in a Cohort of Male Methamphetamine (METH) Users With and Without Kratom (Mitragyna speciosa Korth.) Use History in Malaysia

Methamphetamine (METH) consumption is associated with aggression. Decoction derived from the kratom (Mitragyna speciosa Korth.) leaf has been used as a METH substitute in Southeast Asia. Given its perceived benefit, we investigated the relationship between kratom use and aggression in a treatment sample of METH users with and without kratom use history. Four hundred and three male METH users participated in this cross-sectional study. A semi-structured questionnaire and several objective clinical measures were administered. Results indicate that there were no significant differences in aggression and its dimensions between METH users with and without kratom use history. However, two distinct Clusters (1 and 2) of METH users with kratom use history were studied. Users in Cluster 1 were characterized by a higher quantity and frequency of daily kratom use, longer duration of kratom use, and use of kratom at a younger age. Users in Cluster 2 exhibited the opposite characteristics. Kratom dependence and the first age of kratom use were identified as risk factors for aggression in Cluster 1. The frequency of daily kratom use appeared as a protective factor against aggression in Cluster 2. The results offer partial support to the instrumental kratom use concept; lower frequency (1 to 3 times) of kratom use may potentially minimize aggression in METH users presenting with mild to moderate kratom dependence.

Kratom: A Narrative Review of the Possible Clinical Uses and Dangers of This Opioid-Like Plant

The term "kratom" refers to a plant species formally known as Mitragyna speciosa. Kratom is composed of over 40 alkaloids, a type of organic compound that contains nitrogen. These compounds work primarily via binding to opioid receptors expressed on neurons, where they stimulate signal transduction mechanisms involving the activation of G proteins. Kratom has been shown to cause both a stimulant-like effect and a sedative effect in humans. These studies have shown that use is highest among European-American, middle-class men living in suburban areas. Additionally, individuals who have a history of opioid misuse are also more likely to take kratom. Kratom is used by many different people in the US for numerous different reasons. Some of the most often cited reasons include treating chronic pain conditions, depression, and anxiety. Individuals who used kratom for these reasons typically consumed kratom daily at a dose of 1-3 grams, with the kratom extracted into a powder to be consumed in a capsule. Additionally, there have been reports of kratom being used to treat opioid withdrawal symptoms, as kratom can bind to some of the same receptors as opioids. This manuscript specifically describes trends regarding the use of kratom in the US, pharmacokinetic and pharmacodynamic properties of kratom, potential therapeutic uses of kratom, adverse events caused by kratom, and case studies in the literature regarding patients using kratom.

Beneficial and adverse health effects of kratom (Mitragyna speciosa): A critical review of the literature

Used in Southeast Asia for generations, kratom gained popularity in the United States and elsewhere over the past several decades. Derived from Mitragyna speciosa, kratom preparations including leaves, teas, powders, capsules, and extracts may yield stimulant, analgesic, and opioid-like effects that occur dose-dependently based on concentrations of kratom's key alkaloids, mitragynine and 7-hydroxymitragynine. Such effects are responsible for kratom's potential as a reduced-harm alternative to opiates and as a withdrawal treatment. But these properties are also associated with tolerance development and addictive potential. Given mitragynine and 7-hydroxymitragynine activity on cytochrome P450 isoforms and opioid receptors, adverse effects among polysubstance users are a concern. Current literature on the toxicology of kratom is reviewed, including product alkaloid concentrations, in vitro and in vivo data, epidemiological evidence, and human case data. The potential harms and benefits of kratom products are discussed within an exposure assessment framework, and recommendations for industry are presented. Current evidence indicates that kratom may have therapeutic potential in some persons and that products present few risks with typical, non-polysubstance use. However, few studies identified alkaloid doses at which adverse effects were expected in humans or animals. Such research is needed to inform future assessments of kratom's risks and benefits.

Non-invasive temporal interference brain stimulation reduces preference on morphine-induced conditioned place preference in rats

Long-term use of opioid drugs such as morphine can induce addiction in the central nervous system through dysregulation of the reward system of the brain. Deep brain stimulation (DBS) is a non-pharmacological technique capable of attenuating behavioral responses associated with opioid drug consumption and possesses the capability to selectively activate and target localized brain regions with a high spatial resolution. However, long-term implantation of electrodes in brain tissue may limit the effectiveness of DBS due to changes in impedance, position, and shape of the tip of the stimulation electrode and the risk of infection of nerve tissue around the implanted electrode. The main objective of the current study is to evaluate the effect of temporal interference (TI) brain stimulation on addictive behaviors of morphine-induced conditioned place preference (CPP) in rats. TI stimulation is a non-invasive technique used transcranially to modulate neural activity within targeted brain regions. It involves applying two high-frequency currents with slightly different frequencies, resulting in interference and targeted stimulation of different brain areas with the desired spatial resolution. The results indicated that TI stimulation with the amplitude ofI 1 = I 2 = 0.5 mA, carrier frequency of 2 kHz, frequency difference of 25 Hz, ON-OFF stimulation frequency of 0.25 Hz, and total duration of 10 min in three consecutive days resulted in a significant reduction of morphine preference in the morphine-stimulation group in comparison with the morphine group (p < 0.001). These findings highlight the potential of TI stimulation as a modulatory intervention in mitigating the addictive properties of morphine and provide valuable insights into the therapeutic implications of this stimulation paradigm for treatment of opioid drugs in human subjects.

[Kratom-From natural remedy to addictive drug and back]

BACKGROUND

Kratom/ketum is a psychoactive herbal preparation that has been used for a long time as a remedy and performance-enhancing substance in Southeast Asia. The advancement of globalization is making kratom increasingly more available in the western world, where it is becoming increasingly more used.

OBJECTIVE

The current research on kratom and its ingredients is presented.

MATERIAL AND METHODS

An overview of the use and effects of kratom is exemplary given on the basis of reports. The instrumentalization of the drug and its consequences up to the development of addiction are discussed.

RESULTS

Consumption is accompanied by several instrumentalizeable effects so that kratom is used as a therapeutic substance in the self-management of pain, anxiety and depression as well as other substance addictions. Another benefit comes from the performance-enhancing effects on physical work and in a social context. Consumption is usually well controlled, rarely escalates and has few and mostly mild aversive side effects. The danger arises from consumption particularly when there is an escalation of the dose and from mixed consumption with other psychoactive substances. The main alkaloid mitragynine and the more potent 7‑hydroxy-mitragynine are considered mainly responsible for the effect. Both have a complex pharmacology that involves partial µ‑opioid receptor agonism.

DISCUSSION

Epidemiological, clinical and neurochemical studies have shown that kratom only has a limited addictive drug profile, which might suggest a medical use as a remedy or substitute in addiction treatment.

Comparing withdrawal- and anxiety-like behaviors following oral and subcutaneous oxycodone administration in C57BL/6 mice

Excessive prescribing and misuse of prescription opioids, such as oxycodone, significantly contributed to the current opioid crisis. Although oxycodone is typically consumed orally by humans, parenteral routes of administration have primarily been used in preclinical models of oxycodone dependence. To address this issue, more recent studies have used oral self-administration procedures to study oxycodone seeking and withdrawal in rodents. Behavioral differences, however, following oral oxycodone intake versus parenteral oxycodone administration remain unclear. Thus, the goal of the current studies was to compare anxiety- and withdrawal-like behaviors using established opioid dependence models of either home cage oral intake of oxycodone (0.5 mg/ml) or repeated subcutaneous (s.c.) injections of oxycodone (10 mg/kg) in male and female mice. Here, mice received 10 days of oral or s.c. oxycodone administration, and following 72 h of forced abstinence, anxiety- and withdrawal-like behaviors were measured using elevated zero maze, open field, and naloxone-induced precipitated withdrawal procedures. Global withdrawal scores were increased to a similar degree following oral and s.c. oxycodone use, while both routes of oxycodone administration had minimal effects on anxiety-like behaviors. When examining individual withdrawal-like behaviors, mice receiving s.c. oxycodone exhibited more paw tremors and jumps during naloxone-induced precipitated withdrawal compared with oral oxycodone mice. These results indicate that both models of oxycodone administration are sufficient to elevate global withdrawal scores, but, when compared with oral consumption, s.c. oxycodone injections yielded more pronounced effects on some withdrawal-like behaviors.

Mitragynine (Kratom)-Withdrawal behaviour and cognitive impairments can be ameliorated by an epigenetic mechanism

BACKGROUND AND PURPOSE

Kratom is a preparation from Mitragyna speciosa, which is used as a natural drug preparation for many purposes around the world. However, an overdose of Kratom may cause addiction-like problems including aversive withdrawal states resulting in cognitive impairments via unknown mechanisms. Its main psychoactive alkaloid is mitragynine, showing opioid-like properties.

EXPERIMENTAL APPROACH

Here, we analysed the neuropharmacological effects of mitragynine compared with morphine withdrawal in rats and searched for a pharmacological treatment option that may reverse the occurring cognitive deficits that usually aggravate withdrawal.

KEY RESULTS

We found that withdrawal from 14-day mitragynine (1-10 mg·kg-1·day-1) treatment caused dose-dependent behavioural withdrawal signs resembling those of morphine (5 mg·kg-1·day-1) withdrawal. However, mitragynine (5 and 10 mg·kg-1·day-1) withdrawal also induced impairments in a passive avoidance task. Mitragynine withdrawal not only reduced hippocampal field excitatory postsynaptic potential (fEPSP) amplitudes in basal synaptic transmission and long-term potentiation (LTP) but also reduced epigenetic markers, such as histone H3K9 and H4K12 expression. At the same time, it up-regulates HDAC2 expression. Targeting the epigenetic adaptations with the HDAC inhibitor, SAHA, reversed the effects of mitragynine withdrawal on epigenetic dysregulation, hippocampal input/output curves, paired-pulse facilitation, LTP and attenuated the cognitive deficit. However, SAHA amplified the effects of morphine withdrawal.

CONCLUSION AND IMPLICATIONS

The data from this work show that changes in histone expression and downstream hippocampal plasticity may explain mitragynine, but not morphine, withdrawal behaviours and cognitive impairments. Thus, it may provide a new treatment approach for aversive Kratom/mitragynine withdrawal and addiction.

Psychoactive plant derivatives (ayahuasca, ibogaine, kratom) and their application in opioid withdrawal and use disorder - a narrative review

The opioid epidemic and limited access to treatment for opioid withdrawal (OW) and opioid use disorder (OUD) has led individuals to seek alternative treatments. This narrative review aims to educate clinicians on the mechanisms of action, toxicity, and applications of psychoactive plant-based substances patients may be using to self-treat OUD and OW. We specifically discuss ayahuasca, ibogaine, and kratom as they have the most evidence for applications in OUD and OW from the last decade (2012-2022). Evidence suggests these substances may have efficacy in treating OW and OUD through several therapeutic mechanisms including their unique pharmacodynamic effects, rituals performed around ingestion, and increased neuroplasticity. The current evidence for their therapeutic application in OUD and OW is primarily based on small observational studies or animal studies. High-quality, longitudinal studies are needed to clarify safety and efficacy of these substances in treatment of OW and OUD.

Kratom safety and toxicology in the public health context: research needs to better inform regulation

Although kratom use has been part of life for centuries in Southeast Asia, the availability and use of kratom in the United States (US) increased substantially since the early 2000s when there was little information on kratom pharmacology, use patterns, and effects, all critical to guiding regulation and policy. Here we provide a synthesis of research with several hundred English-language papers published in the past 5 years drawing from basic research, epidemiological and surveillance data, and recent clinical research. This review of available literature aims to provide an integrated update regarding our current understanding of kratom's benefits, risks, pharmacology, and epidemiology, which may inform United States-based kratom regulation. Recent surveillance indicates there are likely several million past-year kratom consumers, though estimates vary widely. Even without precise prevalence data, kratom use is no longer a niche, with millions of United States adults using it for myriad reasons. Despite its botanical origins in the coffee tree family and its polypharmacy, kratom is popularly characterized as an opioid with presumed opioid-system-based risks for addiction or overdose. Neuropharmacology, toxicology, and epidemiology studies show that kratom is more accurately characterized as a substance with diverse and complex pharmacology. Taken together the work reviewed here provides a foundation for future scientific studies, as well as a guide for ongoing efforts to regulate kratom. This work also informs much-needed federal oversight, including by the United States Food and Drug Administration. We conclude with recommendations for kratom regulation and research priorities needed to address current policy and knowledge gaps around this increasingly used botanical product.

Molecular mechanisms of morphine tolerance and dependence; novel insights and future perspectives

Drug addiction is a devastating condition that poses a serious burden on the society. The use of some drugs like morphine for their tremendous analgesic properties is also accompanied with developing tolerance, dependence and the withdrawal symptoms. These symptoms are frequently severe enough to reinforce the person in recovery to start over the use of drug again and hinder the clinical use of drugs like morphine for chronic pain. Research into opioid receptors and related molecular pathways has seen resurgence in the wake of the growing opioid epidemic. The current study provides a comprehensive scientific exploration of the molecular mechanisms and underlying signalling in morphine tolerance and dependence. It also critically evaluates current therapeutic approaches, shedding light on their efficacy and limitations, and future prospects.

Natural products as the therapeutic strategies for addiction

World Drug Report 2023 concluded that 296 million people abused drugs, 39.5 million became addiction and 494,000 died as a direct or indirect result of addiction. Addiction has become a growing problem that affects individuals, their families, societies, countries and even the world. However, treatment for addiction is only limited to some developed countries because of the high cost, difficult implementation, and time consuming. Therefore, there is an urgent need to develop a low-cost, effective drug for the development of addiction treatment in more countries, which is essential for the stability and sustainable development of the world. In this review, it provided an overview of the abuse of common addictive drugs, related disorders, and current therapeutic regimen worldwide, and summarized the mechanisms of drug addiction as reward circuits, neuroadaptation and plasticity, cognitive decision-making, genetics, and environment. According to their chemical structure, 43 natural products and 5 herbal combinations with potential to treat addiction were classified, and their sources, pharmacological effects and clinical trials were introduced. It was also found that mitragine, ibogine, L-tetrahydropalmatine and crocin had greater potential for anti-addiction.

The dopamine D1 receptor antagonist SCH-23390 blocks the acquisition, but not expression of mitragynine-induced conditioned place preference in rats

Mitragynine (MG) is the primary active constituent of Mitragyna speciosa Korth (kratom), a psychoactive Southeast Asian plant with potential therapeutic use. Numerous studies support roles of dopaminergic system in drug reward. However, the involvement of the dopaminergic system in mediating MG reward and drug-seeking is poorly understood. Using conditioned place preference (CPP) paradigm, the present study aims to evaluate the roles of the dopamine (DA) D1 receptor in the acquisition and expression of MG-induced CPP in rats. The effects of SCH-23390, a selective DA D1 receptor antagonist, on the acquisition of MG-induced CPP were first investigated. Rats were pre-treated systemically with SCH-23390 (0, 0.1 and 0.3 mg/kg, i.p.) prior to MG (10 mg/kg) conditioning sessions. Next, we tested the effects of the DA D1 receptor antagonist on the expression of MG-induced CPP. Furthermore, the effects of a MG-priming dose (5 mg/kg) on the reinstatement of extinguished CPP were tested. The results showed that SCH-23390 dose-dependently suppressed the acquisition of a MG-induced CPP. In contrast, SCH-23390 had no effect on the expression of a MG-induced CPP. The findings of this study suggested a crucial role of the DA D1 receptor in the acquisition, but not the expression of the rewarding effects of MG in a CPP test. Furthermore, blockade of the D1-like receptor during conditioning did not prevent MG priming effects on CPP reinstatement test, suggesting no role for the DA D1 receptor in reinstatement sensitivity.

Evaluation of toxicity profile of kratom (Mitragyna speciosa Korth) decoction in rats

Mitragyna speciosa Korth also known as kratom, is an herbal drug preparation for its therapeutic properties and opioid-replacement therapy. Kratom is consumed in a brewed decoction form in Malaysia and to date, no studies have characterized its chemical and toxicity profile. Thus, this study aims to evaluate kratom decoction's safety and toxicity profile after 28 days of treatment. Mitragynine content was quantified in kratom decoction and used as a marker to determine the concentration. Male and female Sprague Dawley rats were orally treated with vehicle or kratom decoction (10, 50 or 150 mg/kg) and two satellite groups were treated with vehicle and kratom decoction (150 mg/kg). Blood and organs were collected for hematology, biochemical and histopathology analysis at the end of treatment. No mortality was found after 28 days of treatment and no significant changes in body weight and hematology profile, except for low platelet count. High amounts of uric acid, AST, ALT and alkaline phosphatase were found in the biochemical analysis. Histological investigation of the heart and lungs detected no alterations except for the kidney, liver and brain tissues. In conclusion, repeated administration of kratom decoction provided some evidence of toxicity in the kidney and liver with no occurrence of mortality.

Kratom: History, pharmacology, current user trends, adverse health effects and potential benefits

Kratom (Mitragyna speciosa Korth.) is a tree native to Southeast Asia with dose-dependent stimulant and opioid-like effects. Dried, powdered leaf material is among the kratom products most commonly consumed in the US and Europe, but other formulations also exist including enriched extracts, resins, tinctures, and edibles. Its prevalence in the US remains debated and the use pattern includes self-treatment of mood disorders, pain, and substance use disorders. Most of the adverse effects of kratom and its alkaloid mitragynine have been reported in the literature as case reports or part of surveys necessitating confirmation by clinical trials. Toxicities associated with kratom consumption have focused on hepatic, cardiac, and CNS effects with the potential to cause fatalities primarily as part of polydrug exposures. Kratom may also present with drug-drug interactions primarily through CYP 3A4 and 2D6 inhibition, although the clinical significance remains unknown to date. The variability in composition of commercially available kratom products complicates generalization of findings and requires further investigation by employing clinical trials. Healthcare professionals should remain cautious in counseling patients on the use of kratom in a therapeutic setting.

Clinical Implications of Kratom (Mitragyna speciosa) Use: a Literature Review

PURPOSE OF REVIEW

This work aims to provide an up-to-date review of the preclinical and clinical scientific literature on the therapeutic value of kratom to better understand the underlying mechanisms related to its use and inform future therapeutic applications.

RECENT FINDINGS

A growing number of studies, mainly of cross-sectional nature, describe the widespread use of kratom by individuals to self-treat pain, psychiatric symptoms, and substance use disorders (SUD) outside a controlled clinical setting. Preclinical evidence suggests kratom is effective as an analgesic agent and might decrease the self-administration of other drugs. A randomized controlled trial has further supported kratom's therapeutic value as an analgesic. Investigations in nonclinical samples of long-term kratom users also indicate its therapeutic benefit in managing SUD symptoms (e.g., craving) and long-term or acute symptoms (e.g., withdrawal) for alcohol, opioids, and other illicit drugs. However, episodes of kratom-related intoxications have also been reported, often due to the adulteration and the contamination of kratom products mainly sold online or mixed toxicities when consumed outside clinical and traditional settings.

SUMMARY

Evidence on the clinical implications of kratom use is still limited and uncertain, with kratom research constantly evolving. Therefore, further randomized trials are needed.

Kratom's Emergence and Persistence Within the US Polydrug Epidemic

Purpose of Review

Use of "kratom" products, derived from the bioactive botanical Mitragyna speciosa have increased amidst US polydrug use epidemics. Kratom alkaloids interact with opioid, serotonergic, adrenergic, and other receptors and regular users have described experiencing a wide range of effects. Some with polydrug use histories have reported using kratom as a substitute for other drugs or to nonmedically self-manage substance use disorder (SUD) symptoms. Data describing this remain scare and come from self-report. We review this literature describing kratom use as a drug substitute, or as a nonmedical "self-treatment" for attenuating dependence or SUD symptoms.

Recent Findings

Kratom products have been documented as being used as a licit and illicit opioid substitute. Use to reduce alcohol or stimulant consumption is less well documented. Although prior and current polydrug use appear common among a some kratom users, it is unclear if co-use is contemporaneous or concomitant. Temporal order of use initiation is typically undocumented. Use for energy and recreation are also increasingly reported.

Summary

Data on kratom consumption come primarily from self-report with significant limitations. Until controlled human laboratory studies have been conducted, we can presently only describe what is known about human kratom use based on self-report. Such data describe real-world kratom use, leaving unaddressed human abuse liability or therapeutic potential of kratom alkaloids. Clinicians should be mindful of use motivations among people with SUD histories, sensitively assessing use. The paucity of data highlights the urgent need to increase funding and research for understanding kratom's effects in humans.

Mitragynine, a primary constituent of kratom reinstates morphine-seeking behaviour in rats

Mitragynine (MG) is a pharmacologically active alkaloid derived from the leaves of Mitragyna speciosa Korth (Kratom). This plant has sparked significant interest as a potential alternative treatment for managing opioid dependence and withdrawal due to its opioid-like pharmacological effects. However, whether MG exposure would trigger opioid-seeking behaviour following abstinence has not been investigated. The present study examined the effects of MG priming on morphine-seeking behaviour in rats. Male Sprague-Dawley rats were initially trained to intravenously self-administer morphine (0.5 mg/kg/infusion) under a fixed ratio-3 schedule of reinforcement. Removal of both morphine infusions and drug-associated cues led to the subsequent extinction of the drug-seeking behaviour. Tests of reinstatement were made following exposure to a randomised order of intraperitoneal injections of MG (3, 10 and 30 mg/kg), morphine (5 mg/kg) and vehicle. Significant levels of drug-seeking behaviour were observed following extended access to morphine self-administration, which was extinguished following removal of morphine and cues indicative of morphine-seeking behaviour, supporting the relapse model. The present finding demonstrated that MG priming in a dose of 10 mg/kg resulted in the reinstatement of morphine-seeking behaviour, whereas the higher MG dose (30 mg/kg) tested suppressed the seeking response. This study indicated that exposure to a low MG dose may increase the likelihood of relapsing to opioids, suggesting that the potential of MG as a treatment for opioid management merits further scientific assessment of its ability to trigger relapse to opioid abuse.

Kratom (M. speciosa) exposure during adolescence caused long-lasting cognitive behavioural deficits associated with perturbated brain metabolism pathways in adult rats

Kratom (M. speciosa Korth) is an herbal plant native to Southeast Asia. The leaves have been widely used to alleviate pain and opioid withdrawal symptoms. However, the increasing trend of recreational use of kratom among youth is concerning because substance abuse may render the adolescent brain more susceptible to neuropathological processes, causing dramatic consequences that persist into adulthood. Therefore, the present study aimed to investigate the long-term effects of mitragynine, the main alkaloid and lyophilized kratom decoction (LKD) exposure during adolescence on cognitive behaviours and brain metabolite profiles in adult rats. Adolescent male Sprague-Dawley rats were given mitragynine (3, 10 or 30mg/kg) or LKD orally for 15 consecutive days during postnatal days 31-45 (PND31-45). Behavioural testing was performed during adulthood (PND70-84) and the brains were subjected to metabolomic analysis. The results show that a high dose of mitragynine impaired long-term object recognition memory. Social behaviour and spatial learning were not affected, but both mitragynine and LKD impaired reference memory. Brain metabolomic study revealed several altered metabolic pathways that may be involved in the cognitive behavioural effects of LKD and mitragynine exposure. These pathways include arachidonic acid, taurine and hypotaurine, pantothenate and CoA biosynthesis, and tryptophan metabolism, while the N-isovalerylglycine was identified as the potential biomarker. In summary, adolescent kratom exposure can cause long-lasting cognitive behavioural deficits and alter brain metabolite profiles that are still evident in adulthood. This finding also indicates that the adolescent brain is vulnerable to the impact of early kratom use.

Analgesic effects of main indole alkaloid of kratom, mitragynine in acute pain animal model

Mitragynine exerts its analgesic effect mainly via opioid receptors activation. Additionally, the effect may be mediated via mitragynine's anti-inflammatory property and non-opioid receptor pain pathways, namely through the TRPV1 receptor. No studies identify hitherto, hence, the current study aimed to investigate the mitragynine's analgesic effect via the anti-inflammatory property, non-opioid receptor (TRPV1) and the effective dose (ED) to alleviate pain. Male and female Sprague Dawley rats were pre-treated intraperitoneally with either mitragynine (1, 5, 10, 13, 15 or 30 mg/kg), vehicle, or indomethacin (1 mg/kg) 30 min before inducing inflammatory pain using acetic acid. The writhes and pain-related withdrawal behaviour occurrence were counted within a 1-h duration. Percentage of writhes inhibition, pain-related withdrawal behaviour aggregate, ED50 and ED95 were determined. The body temperature was recorded and TRPV1 expression in the rats' brains was measured. Mitragynine (except 1 mg/kg) significantly reduced the number of writhes compared with the vehicle administered group. Mitragynine (30 mg/kg) demonstrated 99.5% inhibition of writhing behaviour and low withdrawal behaviour score compared with vehicle and indomethacin and successfully blocked the hypothermia induced by acetic acid. The overall ED50 and ED95 values of mitragynine were 3.62 and 20.84 mg/kg, respectively. The percentage of writhing inhibition and withdrawal behaviour were similar in both genders. Mitragynine (15 and 30 mg/kg) significantly reduced the TRPV1 expression in the brain of the rats. Mitragynine alleviated pain-like behaviour and showed analgesic effects via anti-inflammatory and non-opioid receptor pathways. The findings also suggest that mitragynine might regulate some physiological functions of the rat.

The role of AMPA and NMDA receptors in mitragynine effects on hippocampal synaptic plasticity

Mitragynine, an indole alkaloid from the plant Mitragyna speciosa (Kratom), has been reported to modify hippocampal synaptic transmission. However, the role of glutamatergic neurotransmission modulating synaptic plasticity in mitragynine-induced synaptic changes is still unknown. Here, we determined the role of AMPA- and NMDA glutamate receptors in mitragynine-induced synaptic plasticity in the hippocampus. Male Sprague Dawley rats received either vehicle or mitragynine (10 mg/kg), with or without the AMPA receptor antagonist, NBQX (3 mg/kg), or the NMDA receptor antagonist, MK-801 (0.2 mg/kg). Field excitatory postsynaptic potentials (fEPSP) during baseline, paired-pulse facilitation (PPF) and long-term potentiation (LTP) were recorded in-vivo in the hippocampal CA1 area of anaesthetised rats. Basal synaptic transmission and LTP were significantly impaired after mitragynine, NBQX, and MK-801 alone, without an effect on PPF. Combined effects suggest a weak functional AMPA- as well as NMDA receptor antagonist action of mitragynine.

Exploring adolescents' practice and perspective on the use and misuse of kratom in northwest Malaysia

Kratom is a plant homogenous to Southeast Asia with a long history of traditional use as medicinal herbs. However, recent years have witnessed its pervasive infiltration into international audience with growing public health concern. This cross-sectional study was conducted from 1 August 2017 till 31 August 2018 aiming to explore the practice and perspectives of kratom use and misuse among adolescents in northwest Malaysia. The study involved a self-administered questionnaire that was designed for the purpose of the study. The instrument had undergone prior validation process with a good overall internal reliability for the knowledge domain (Cronbach's alpha = 0.728) and attitude domain (Cronbach's alpha = 0.700). The questionnaire was distributed to 135 respondents involving adolescents aged 13 to 19 years old via convenience (non-kratom user) and snowball sampling (kratom users). There were 65 (47.8%) kratom users, while 70 (51.5%) were kratom-naïve. Among the kratom users, peer influence was the most common reason for them to be first involved with kratom, 26 (41.3%) whereas the reasons for kratom use quoted were to improve physical stamina, 10 (16.4%), as painkiller, 9 (14.8%), and to be accepted by peers, 7 (11.5%). Multiple logistic regression found that older age (95% CI: 0.13, 0.58; p = 0.001) and being active smokers (95% CI: 39.33, 980.63; p < 0.001) significantly predict kratom use among adolescents. The emerging trend of kratom abuse and misuse especially among the younger generation in Malaysia is raising concern and warrants social and governmental vigilance.

Opioid replacement therapy with methadone or buprenorphine effects on male mice reproduction

RATIONALE

Opioid use disorders are commonly treated by long-acting agonist opioids including methadone and buprenorphine which could affect various aspects of male reproduction especially spermatogenesis.

OBJECTIVES

We aimed to determine whether detoxification with methadone or buprenorphine was associated with reproductive disorders in male mice.

METHODS

We orally induced morphine dependence in NMRI male mice, and then performed detoxification programs using either methadone or buprenorphine. Testis architecture and sperm parameters including sperm nuclear DNA integrity, mitochondrial activity, oxidative stress in seminal plasma, and routine sperm parameters were assessed to find the involved mechanisms.

RESULTS

The number of Leydig cells and the thickness of germinal epithelium reduced following morphine use and increased differently after detoxification with methadone or buprenorphine. Morphine dependence and detoxification with methadone and buprenorphine had different effects on sperm parameters. Morphine altered chromatin integrity, mitochondrial activity, and oxidative stress in sperm. Detoxification with methadone improved mitochondrial activity but worsened chromatin integrity, whereas detoxification with buprenorphine improved neither chromatin integrity nor mitochondrial activity. Seminal plasma oxidative stress was higher in the treated groups compared to control groups but was comparable among treatment groups. Our study revealed that long-term morphine use followed by detoxification with methadone or buprenorphine impairs testis structure and sperm parameters. Detoxification from morphine use with methadone and buprenorphine led to different preclinical outcomes in semen quality parameters, including chromatin integrity. Therefore, clinical detoxification protocols should be performed more cautiously, considering the desire of the individuals to reproduce.

Adolescent kratom exposure affects cognitive behaviours and brain metabolite profiles in Sprague-Dawley rats

Adolescence is a critical developmental period during which exposure to psychoactive substances like kratom (Mitragyna speciosa) can cause long-lasting deleterious effects. Here, we evaluated the effects of mitragynine, the main alkaloid of kratom, and lyophilised kratom decoction (LKD) on cognitive behaviours and brain metabolite profiles in adolescent rats. Male Sprague-Dawley rats (Postnatal day, PND31) were given vehicle, morphine (5 mg/kg), mitragynine (3, 10, or 30 mg/kg), or LKD (equivalent dose of 30 mg/kg mitragynine) for 15 consecutive days. Later, a battery of behavioural testing was conducted, brain was extracted and metabolomic analysis was performed using LCMS-QTOF. The results showed that mitragynine did not affect the recognition memory in the novel object recognition task. In the social interaction task, morphine, mitragynine, and LKD caused a marked deficit in social behaviour, while in Morris water maze task, mitragynine and LKD only affected reference memory. Metabolomic analysis revealed distinct metabolite profiles of animals with different treatments. Several pathways that may be involved in the effects of kratom exposure include arachidonic acid, pantothenate and CoA, and tryptophan pathways, with several potential biomarkers identified. These findings suggest that adolescent kratom exposure can cause cognitive behavioural deficits that may be associated with changes in the brain metabolite profiles.

Variations in mitragynine content in the naturally growing Kratom (Mitragyna speciosa) population of Thailand

We analyzed the content of mitragynine (MG) found in kratom leaves (Mitragyna speciosa) and the influence of different environmental conditions (air and soil variables) on the yield in various regions of Thailand. The content of MG in kratom leaves ranged from 7.5 - 26.6 mg g^-1 of dry leaf weight. Canonical correspondence analysis showed that the most significant environmental variables affecting the MG content among the various regions were light intensity, relative humidity, soil volumetric water content (VW), soil pH, and calcium. This study is a first step towards providing information about environmental conditions suitable to maximize the quality and quantity of bioactive alkaloids in kratom. Future studies should focus on leaf collection and the post-harvest processes in order to assure the desired alkaloidal content in finished products, when produced under suitable environmental conditions identified in this study.

Kratom as an opioid alternative: harm, or harm reduction? A systematic review of literature

Background: Kratom (Mitragyna speciosa Korth.) products are increasingly endorsed for self-management of multiple ailments, including as opioid substitution. The FDA has expressed that there is no evidence to indicate that this botanical is safe or effective for any medical use.Objective: We systematically review the current state of the literature concerning the impact of kratom and its alkaloids in all paradigms that involve opioids.Methods: A keyword search of online literature databases identified 16 preclinical studies, 25 case reports, and 10 observational studies meeting our pre-selected criteria.Results: All rodent models support alkaloids' action on opioid receptors, translating in their ability to mitigate opioid withdrawal. Some studies found mitragynine (MG) to have less reinforcing properties than morphine, and possessing tolerance-sparing properties when coadministered with morphine. Two studies that assessed 7-hydroxymitragynine (7OHMG) found it to substitute for morphine with potential for tolerance and dependence. Aside from addiction development, case reports outline a variety of confounding toxicities. Ten surveys of users, some conducted with assistance from pro-kratom lobbying organizations, find a high self-reported efficacy as an opioid substitute, with minimal reported adverse effects.Conclusion: With no reported controlled human clinical trials, in the light of rising concerns surrounding kratom's liabilities, there is insufficient evidence to allow any conclusions to be drawn. Case reports and observational studies carry significant bias toward harm and efficacy, respectively. Existing animal studies are heterogeneous in methodology and ultimately findings, with concern for interspecies variability and human translatability. Further research should investigate the safety and efficacy of using kratom alkaloids as opioid substitutes.

Endogenous opiates and behavior: 2020

This paper is the forty-third consecutive installment of the annual anthological review of research concerning the endogenous opioid system, summarizing articles published during 2020 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 (1), the roles of these opioid peptides and receptors in pain and analgesia in animals (2) and humans (3), opioid-sensitive and opioid-insensitive effects of nonopioid analgesics (4), opioid peptide and receptor involvement in tolerance and dependence (5), stress and social status (6), learning and memory (7), eating and drinking (8), drug abuse and alcohol (9), sexual activity and hormones, pregnancy, development and endocrinology (10), mental illness and mood (11), seizures and neurologic disorders (12), electrical-related activity and neurophysiology (13), general activity and locomotion (14), gastrointestinal, renal and hepatic functions (15), cardiovascular responses (16), respiration and thermoregulation (17), and immunological responses (18).

Searching for a Signal: Self-Reported Kratom Dose-Effect Relationships Among a Sample of US Adults With Regular Kratom Use Histories

There is limited understanding regarding kratom use among US adults. Although motivations for use are increasingly understood, typical kratom doses, threshold of (low and high) doses for perceived effectiveness, and effects produced during cessation are not well documented. We aimed to extend prior survey work by recruiting adults with current and past kratom exposure. Our goal was to better understand kratom dosing, changes in routines, and perception of effects, including time to onset, duration, and variability of beneficial and adverse outcomes from use and cessation. Among respondents who reported experiencing acute kratom effects, we also sought to determine if effects were perceived as helpful or unhelpful in meeting daily obligations. Finally, we attempted to detect any signal of a relationship between the amount of kratom consumed weekly and weeks of regular use with ratings of beneficial effects from use and ratings of adverse effects from cessation. We conducted an online survey between April-May 2021 by re-recruiting participants from a separate study who reported lifetime kratom use. A total of 129 evaluable surveys were collected. Most (59.7%) had used kratom >100 times and reported currently or having previously used kratom >4 times per week (62 weeks on average). Under half (41.9%) reported that they considered themselves to be a current "regular kratom user." A majority (79.8%) reported experiencing acute effects from their typical kratom dose and that onset of effects began in minutes but dissipated within hours. Over a quarter reported that they had increased their kratom dose since use initiation, whereas 18.6% had decreased. Greater severity of unwanted effects from ≥1 day of kratom cessation was predicted by more weeks of regular kratom use (β = 6.74, p = 0.02). Acute kratom effects were largely reported as compatible with, and sometimes helpful in, meeting daily obligations. In the absence of human laboratory studies, survey methods must be refined to more precisely assess dose-effect relationships. These can help inform the development of controlled observational and experimental studies needed to advance the public health understanding of kratom product use.

Physiological dependence to mitragynine indicated by a rapid cross-dependence procedure with heroin-dependent mice

The potential of mitragynine to produce physiological dependence (withdrawal) was assessed using a rapid assessment procedure with male ICR mice exposed to heroin-admixed food followed by naloxone (subcutaneously, s.c.) precipitation of withdrawal. Initial studies indicated that 3 days of exposure to 3.0 mg/g of heroin-admixed food followed by naloxone (0.6 mg/kg) reliably precipitated withdrawal jumping and weight loss. Lower concentrations of heroin-admixed food and lower doses of naloxone produced fewer withdrawal signs. A longer exposure to heroin-admixed food did not produce significantly greater amounts of jumping or weight loss. Further, these withdrawal signs were dose-dependently reversed by s.c. administration of heroin immediately following naloxone administration. Mitragynine (s.c.) also dose-dependently suppressed naloxone-precipitated withdrawal signs. Additionally, both jumping and weight loss were suppressed over a comparable range of mitragynine doses when administered by gavage with a noticeably, but not significantly, higher potency than with s.c. administration. The ED₅₀ values for mitragynine for the suppression of withdrawal by any route (354-911 μmol/kg) were greater than the minimally effective dose that decreased locomotor activity (251 μmol/kg) and from 40- to 104-fold greater than those for heroin. The results suggest inherent opioid dependence liability of mitragynine. The in vivo potency relations between mitragynine and heroin are consistent with a conclusion of dependence-producing effects, indicated by the suppression of withdrawal, comparable to standard opioid μ-receptor agonists, differing primarily in terms of potency. The present paper provides a method for the rapid assessment of physiological dependence liability applicable to other kratom plant constituents or any potential opioid dependence-producing agents.

Kratom Abuse Potential 2021: An Updated Eight Factor Analysis

Drugs are regulated in the United States (US) by the Controlled Substances Act (CSA) if assessment of their abuse potential, including public health risks, show such control is warranted. An evaluation via the 8 factors of the CSA provides the comprehensive assessment required for permanent listing of new chemical entities and previously uncontrolled substances. Such an assessment was published for two kratom alkaloids in 2018 that the Food and Drug Administration (FDA) have identified as candidates for CSA listing: mitragynine (MG) and 7-hydroxymitragynine (7-OH-MG) (Henningfield et al., 2018a). That assessment concluded the abuse potential of MG was within the range of many other uncontrolled substances, that there was not evidence of an imminent risk to public health, and that a Schedule I listing (the only option for substances that are not FDA approved for therapeutic use such as kratom) carried public health risks including drug overdoses by people using kratom to abstain from opioids. The purpose of this review is to provide an updated abuse potential assessment reviewing greater than 100 studies published since January 1, 2018. These include studies of abuse potential and physical dependence/withdrawal in animals; in-vitro receptor binding; assessments of potential efficacy treating pain and substance use disorders; pharmacokinetic/pharmacodynamic studies with safety-related findings; clinical studies of long-term users with various physiological endpoints; and surveys of patterns and reasons for use and associated effects including dependence and withdrawal. Findings from these studies suggest that public health is better served by assuring continued access to kratom products by consumers and researchers. Currently, Kratom alkaloids and derivatives are in development as safer and/or more effective medicines for treating pain, substances use disorders, and mood disorders. Placing kratom in the CSA via scheduling would criminalize consumers and possession, seriously impede research, and can be predicted to have serious adverse public health consequences, including potentially thousands of drug overdose deaths. Therefore, CSA listing is not recommended. Regulation to minimize risks of contaminated, adulterated, and inappropriately marketed products is recommended.

Mitragyna Species as Pharmacological Agents: From Abuse to Promising Pharmaceutical Products

Mitragyna is a genus belonging to the Rubiaceae family and is a plant endemic to Asia and Africa. Traditionally, the plants of this genus were used by local people to treat some diseases from generation to generation. Mitragyna speciosa (Korth.) Havil. is a controversial plant from this genus, known under the trading name “kratom”, and contains more than 40 different types of alkaloids. Mitragynine and 7-hydroxymitragynine have agonist morphine-like effects on opioid receptors. Globally, Mitragyna plants have high economic value. However, regulations regarding the circulation and use of these commodities vary in several countries around the world. This review article aims to comprehensively examine Mitragyna plants (mainly M. speciosa) as potential pharmacological agents by looking at various aspects of the plants. A literature search was performed and information collected using electronic databases including Scopus, ScienceDirect, PubMed, directory open access journal (DOAJ), and Google Scholar in early 2020 to mid-2021. This narrative review highlights some aspects of this genus, including historical background and botanical origins, habitat, cultivation, its use in traditional medicine, phytochemistry, pharmacology and toxicity, abuse and addiction, legal issues, and the potential of Mitragyna species as pharmaceutical products.

Mitragynine improves cognitive performance in morphine-withdrawn rats

RATIONALE

The treatment of opiate addiction is an unmet medical need. Repeated exposure to opiates disrupts cognitive performance. Opioid substitution therapy, with, e.g., methadone, may further exacerbate the cognitive deficits. Growing evidence suggests that mitragynine, the primary alkaloid from the Kratom (Mitragyna speciosa) leaves, may serve as a promising alternative therapy for opiate addiction. However, the knowledge of its health consequences is still limited.

OBJECTIVES

We aimed to examine the cognitive effects of mitragynine substitution in morphine-withdrawn rats. Furthermore, we asked whether neuronal addiction markers like the brain-derived neurotrophic factor (BDNF) and Ca²⁺/calmodulin-dependent kinase II alpha (αCaMKII) might mediate the observed effects.

METHODS

Male Sprague-Dawley rats were given morphine at escalating doses before treatment was discontinued to induce a spontaneous morphine withdrawal. Then, vehicle or mitragynine (5 mg/kg, 15 mg/kg, or 30 mg/kg) substitution was given for 3 days. A vehicle-treated group was used as a control. Withdrawal signs were scored after 24 h, 48 h, and 72 h, while novel object recognition (NOR) and attentional set-shifting (ASST) were tested during the substitution period.

RESULTS

Discontinuation of morphine significantly induced morphine withdrawal signs and cognitive deficit in the ASST. The substitution with mitragynine was able to alleviate the withdrawal signs. Mitragynine did not affect the recognition memory in the NOR but significantly improved the reversal learning deficit in the morphine-withdrawn rats.

CONCLUSIONS

These data support the idea that mitragynine could be used as safe medication therapy to treat opiate addiction with beneficial effects on cognitive deficits.

A systematic review of (pre)clinical studies on the therapeutic potential and safety profile of kratom in humans

INTRODUCTION

Kratom (Mitragyna speciosa) is a tropical plant traditionally used as an ethnomedicinal remedy for several conditions in South East Asia. Despite the increased interest in its therapeutical benefits in Western countries, little scientific evidence is available to support such claims, and existing data remain limited to kratom's chronic consumption.

OBJECTIVE

Our study aims to investigate (pre)clinical evidence on the efficacy of kratom as a therapeutic aid and its safety profile in humans.

METHODS

A systematic literature search using PubMed and the Medline database was conducted between April and November 2020.

RESULTS

Both preclinical (N = 57) and clinical (N = 18) studies emerged from our search. Preclinical data indicated a therapeutic value in terms of acute/chronic pain (N = 23), morphine/ethanol withdrawal, and dependence (N = 14), among other medical conditions (N = 26). Clinical data included interventional studies (N = 2) reporting reduced pain sensitivity, and observational studies (N = 9) describing the association between kratom's chronic (daily/frequent) use and safety issues, in terms of health consequences (e.g., learning impairment, high cholesterol level, dependence/withdrawal).

CONCLUSIONS

Although the initial (pre)clinical evidence on kratom's therapeutic potential and its safety profile in humans is encouraging, further validation in large, controlled clinical trials is required.

In vitro and in vivo pharmacology of kratom

Kratom products have been historically and anecdotally used in south Asian countries for centuries to manage pain and opioid withdrawal. The use of kratom products has dramatically increased in the United States. More than 45 kratom alkaloids have been isolated, yet the overall pharmacology of the individual alkaloids is still not well characterized. The purpose of this chapter is to summarize in vitro and in vivo opioid activities of the primary kratom alkaloid mitragynine and its more potent metabolite 7-hydroxymitragynine. Following are experimental procedures described to characterize opioid receptor activity; receptor binding and functional assays, antinociceptive assays, operant conditioning assays, and respiratory plethysmography. The capacity of kratom alkaloids to confer tolerance and physical dependence as well as their pharmacokinetic properties are also summarized. The data reviewed here suggest that kratom products and mitragynine possess low efficacy agonist activity at the mu-opioid receptor in vivo. In addition, kratom products and mitragynine have been demonstrated to antagonize the effects of high efficacy mu-opioid agonists. The data further suggest that 7-hydroxymitragynine formed in vivo by metabolism of mitragynine may be minimally involved in the overall behavioral profile of mitragynine and kratom, whereas 7-hydroxymitragynine itself, at sufficiently high doses administered exogenously, shares many of the same abuse- and dependence-related behavioral effects associated with traditional opioid agonists. The apparent low efficacy of kratom products and mitragynine at mu-opioid receptors supports the development of these ligands as effective and potentially safe medications for opioid use disorder.

Kratom Alkaloids: Interactions With Enzymes, Receptors, and Cellular Barriers

Parallel to the growing use of kratom, there is a wealth of evidence from self-report, preclinical, and early clinical studies on therapeutic benefits of its alkaloids in particular for treating pain, managing substance use disorder, and coping with emotional or mental health conditions. On the other hand, there are also reports on potential health risks concerning kratom use. These two aspects are often discussed in reviews on kratom. Here, we aim to highlight specific areas that are of importance to give insights into the mechanistic of kratom alkaloids pharmacological actions. This includes their interactions with drug-metabolizing enzymes and predictions of clinical drug-drug interactions, receptor-binding properties, interactions with cellular barriers in regards to barrier permeability, involvement of membrane transporters, and alteration of barrier function when exposed to the alkaloids.

Clinical Pharmacology of the Dietary Supplement, Kratom (Mitragyna speciosa)

Kratom (Mitragyna speciosa) consists of over 40 alkaloids with two of them, mitragynine (MG) and 7-OH-mitragynine (7-OH-MG) being the main psychoactive compounds. MG and 7-OH-MG each target opioid receptors and have been referred to as atypical opioids. They exert their pharmacologic effects on the μ, δ, and κ opioid receptors. In addition, they affect adrenergic, serotonergic, and dopaminergic pathways. Kratom has been touted as an inexpensive, legal alternative to standard opioid replacement therapy such as methadone and buprenorphine. Other uses for kratom include chronic pain, attaining a "legal high," and numerous CNS disorders including anxiety depression and post-traumatic stress disorder (PTSD). Kratom induces analgesia and mild euphoria with a lower risk of respiratory depression or adverse central nervous system effects compared to traditional opioid medications. Nonetheless, kratom has been associated with both physical and psychological dependence with some individuals experiencing classic opioid withdrawal symptoms upon abrupt cessation. Kratom use has been linked to serious adverse effects including liver toxicity, seizures, and death. These risks are often compounded by poly-substance abuse. Further, kratom may potentiate the toxicity of coadministered medications through modulation of cytochrome P450, P-glycoprotein, and uridine diphosphate glucuronosyltransferase enzymes (UGDT). In 2016 the U.S. Drug Enforcement Administration (DEA) took steps to classify kratom as a federal schedule 1 medication; however, due to public resistance, this plan was set aside. Until studies are conducted that define kratom's role in treating opioid withdrawal and/or other CNS conditions, kratom will likely remain available as a dietary supplement for the foreseeable future. This article is protected by copyright. All rights reserved.

Pentylenetetrazol-like stimulus is not produced following naloxone-precipitated mitragynine withdrawal in rats

RATIONALE

Kratom (Mitragyna speciosa Korth), a native medicinal plant of Southeast Asia, is proposed to exhibit potential therapeutic value as an opioid substitute. However, studies of its negative emotional states resulting from withdrawal particularly of its main psychoactive compound, mitragynine (MG), are limited.

OBJECTIVES

Using the pentylenetetrazol (PTZ) discrimination assay, this study aims to investigate the effects of MG in responding to the PTZ stimulus and to assess the generalisation effects of withdrawal from MG to the PTZ stimulus.

METHODS

Rats (n = 20) were trained on a tandem (FR-10, VI-15) schedule of food reinforcement to press one lever after administration of the anxiogenic compound PTZ (16 mg/kg, i.p.) and an alternate lever after vehicle. Following acute tests, training was suspended, and rats were chronically treated with MG or morphine at 8-h intervals for 9 days and withdrawal was precipitated on the tenth day using naloxone (1 mg/kg, i.p.). The rats were tested for generalisation to PTZ at 2, 8 and 24 h after the last dose of MG or morphine administration.

RESULTS

Unlike morphine that produced dose-related PTZ-like stimulus, MG at 3, 10, 30 and 45 mg/kg doses showed no substitution to the PTZ discriminative stimulus. In contrast to morphine which produced a time-dependent generalisation to the PTZ stimulus, naloxone did not precipitate withdrawal effects in MG-treated rats as they selected the vehicle lever at three withdrawal time points.

CONCLUSION

These results demonstrate that MG produces a very different response to morphine withdrawal that is not associated with anxiogenic-like subjective symptoms. These characteristics of MG may provide further support for use as a novel pharmacotherapeutic intervention for managing opioid use disorder.

Anterior cingulate cortex is necessary for spontaneous opioid withdrawal and withdrawal-induced hyperalgesia in male mice

The anterior cingulate cortex (ACC) is implicated in many pathologies, including depression, anxiety, substance-use disorders, and pain. There is also evidence from brain imaging that the ACC is hyperactive during periods of opioid withdrawal. However, there are limited data contributing to our understanding of ACC function at the cellular level during opioid withdrawal. Here, we address this issue by performing ex vivo electrophysiological analysis of thick-tufted, putative dopamine D2 receptor expressing, layer V pyramidal neurons in the ACC (ACC L5 PyNs) in a mouse model of spontaneous opioid withdrawal. We found that escalating doses of morphine (20, 40, 60, 80, and 100 mg/kg, i.p. on days 1-5, respectively) injected twice daily into male C57BL/6 mice evoked withdrawal behaviors and an associated withdrawal-induced mechanical hypersensitivity. Brain slices prepared 24 h following the last morphine injection showed increases in ACC L5 thick-tufted PyN-intrinsic membrane excitability, increases in membrane resistance, reductions in the rheobase, and reductions in HCN channel-mediated currents (I_H). We did not observe changes in intrinsic or synaptic properties on thin-tufted, dopamine D1-receptor-expressing ACC L5 PyNs recorded from male Drd1a-tdTomato transgenic mice. In addition, we found that chemogenetic inhibition of the ACC blocked opioid-induced withdrawal and withdrawal-induced mechanical hypersensitivity. These results demonstrate that spontaneous opioid withdrawal alters neuronal properties within the ACC and that ACC activity is necessary to control behaviors associated with opioid withdrawal and withdrawal-induced mechanical hypersensitivity. The ability of the ACC to regulate both withdrawal behaviors and withdrawal-induced mechanical hypersensitivity suggests overlapping mechanisms between two seemingly distinguishable behaviors. This commonality potentially suggests that the ACC is a locus for multiple withdrawal symptoms.

Escalating morphine dosage fails to elicit conditioned analgesia in a preclinical chronic neuropathic pain model

Many people with chronic pain escalate their opioid dosage to counteract tolerance effects. A treatment regimen consisting of placebos admixed with opioids has been suggested as a possible therapeutic option that could reduce the harm of long-term opioid use. However, the analgesic efficacy of such a regimen requires further investigation before widespread adoption. We have recently reported that a 4-day pharmacological conditioning procedure, which paired morphine (6 mg/kg) with contextual cues, elicited placebo analgesia in subpopulations of male (35%) and female (25%) rats with sciatic nerve chronic constriction injury (CCI). Here, we investigated how an escalating morphine dosage during conditioning affects the incidence and strength of placebo analgesia. Forty-four male, Sprague-Dawley rats received CCI. Thirty-eight (86%) rats developed strong cold allodynia by day 6 post-surgery, as measured by hind paw withdrawal (HPW) behaviour on a 5°C cold plate (120 s). In this experiment, pharmacological conditioning consisted of an escalating morphine dose over 4 days (8/9/10/12 mg/kg). This dosing regimen produced strong reductions in HPW behaviour and counteracted the effects of morphine tolerance during conditioning. However, none of the rats given the placebo treatment (n = 12) demonstrated reductions in HPW behaviour when morphine was substituted for saline (i.e. placebo analgesia), but instead showed a strong behavioural response (rearing). These results demonstrate that a high, escalating dose of morphine failed to produce conditioned placebo analgesia in rats with CCI. It is possible that admixing placebos with opioids may be similarly ineffective in chronic pain patients when the opioids regimen is high or escalating.

Methadone, Buprenorphine, and Clonidine Attenuate Mitragynine Withdrawal in Rats

Background: Kratom or Mitragyna speciosa Korth has been widely used to relieve the severity of opioid withdrawal in natural settings. However, several studies have reported that kratom may by itself cause dependence following chronic consumption. Yet, there is currently no formal treatment for kratom dependence. Mitragynine, is the major psychoactive alkaloid in kratom. Chronic mitragynine treatment can cause addiction-like symptoms in rodent models including withdrawal behaviour. In this study we assessed whether the prescription drugs, methadone, buprenorphine and clonidine, could mitigate mitragynine withdrawal effects. In order to assess treatment safety, we also evaluated hematological, biochemical and histopathological treatment effects. Methods: We induced mitragynine withdrawal behaviour in a chronic treatment paradigm in rats. Methadone (1.0 mg/kg), buprenorphine (0.8 mg/kg) and clonidine (0.1 mg/kg) were i.p. administered over four days during mitragynine withdrawal. These treatments were stopped and withdrawal sign assessment continued. Thereafter, toxicological profiles of the treatments were evaluated in the blood and in organs. Results: Chronic mitragynine treatment caused significant withdrawal behaviour lasting at least 5 days. Methadone, buprenorphine, as well as clonidine treatments significantly attenuated these withdrawal signs. No major effects on blood or organ toxicity were observed. Conclusion: These data suggest that the already available prescription medications methadone, buprenorphine, and clonidine are capable to alleviate mitragynine withdrawal signs rats. This may suggest them as treatment options also for problematic mitragynine/kratom use in humans.

Kratom Alkaloids, Natural and Semi-Synthetic, Show Less Physical Dependence and Ameliorate Opioid Withdrawal

Chronic administration of opioids produces physical dependence and opioid-induced hyperalgesia. Users claim the Thai traditional tea "kratom" and component alkaloid mitragynine ameliorate opioid withdrawal without increased sensitivity to pain. Testing these claims, we assessed the combined kratom alkaloid extract (KAE) and two individual alkaloids, mitragynine (MG) and the analog mitragynine pseudoindoxyl (MP), evaluating their ability to produce physical dependence and induce hyperalgesia after chronic administration, and as treatments for withdrawal in morphine-dependent subjects. C57BL/6J mice (n = 10/drug) were administered repeated saline, or graded, escalating doses of morphine (intraperitoneal; i.p.), kratom alkaloid extract (orally, p.o.), mitragynine (p.o.), or MP (subcutaneously, s.c.) for 5 days. Mice treated chronically with morphine, KAE, or mitragynine demonstrated significant drug-induced hyperalgesia by day 5 in a 48 °C warm-water tail-withdrawal test. Mice were then administered naloxone (10 mg/kg, s.c.) and tested for opioid withdrawal signs. Kratom alkaloid extract and the two individual alkaloids demonstrated significantly fewer naloxone-precipitated withdrawal signs than morphine-treated mice. Additional C57BL/6J mice made physically dependent on morphine were then used to test the therapeutic potential of combined KAE, mitragynine, or MP given twice daily over the next 3 days at either a fixed dose or in graded, tapering descending doses. When administered naloxone, mice treated with KAE, mitragynine, or MP under either regimen demonstrated significantly fewer signs of precipitated withdrawal than control mice that continued to receive morphine. In conclusion, while retaining some liabilities, kratom, mitragynine, and mitragynine pseudoindoxyl produced significantly less physical dependence and ameliorated precipitated withdrawal in morphine-dependent animals, suggesting some clinical value.

Viral vector-mediated gene therapy for opioid use disorders

Chronic exposure to opioids typically results in adverse consequences. Opioid use disorder (OUD) is a disease of the CNS with behavioral, psychological, neurobiological, and medical manifestations. OUD induces a variety of changes of neurotransmitters/neuropeptides in the nervous system. Existing pharmacotherapy, such as opioid maintenance therapy (OMT) is the mainstay for the treatment of OUD, however, current opioid replacement therapy is far from effective for the majority of patients. Pharmacological therapy for OUD has been challenging for many reasons including debilitating side-effects. Therefore, developing an effective, non-pharmacological approach would be a critical advancement in improving and expanding treatment for OUD. Viral vector mediated gene therapy provides a potential new approach for treating opioid abused patients. Gene therapy can supply targeting gene products directly linked to the mechanisms of OUD to restore neurotransmitter and/or neuropeptides imbalance, and avoid the off-target effects of systemic administration of drugs. The most commonly used viral vectors in rodent studies of treatment of opioid-used disorder are based on recombinant adenovirus (AV), adeno-associated virus (AAV), lentiviral (LV) vectors, and herpes simplex virus (HSV) vectors. In this review, we will focus on the recent progress of viral vector mediated gene therapy in OUD, especially morphine tolerance and withdrawal.

Kratom use for depression/anxiety self-management: challenges during the COVID-19 pandemic - A case report

Background

Kratom is a psychoactive plant preparation originating from Southeast Asia. It has been used as a recreational and performance drug in Southeast Asia, and is now increasingly used in Europe and the U.S.

Case report

We describe the case of a 63-year-old man who presented for treatment after his long-term Kratom use failed as a self-management for persistent major depression (ICD 10: F33.2) and a generalized anxiety disorder (ICD-10: F41.1). The failure coincided with emerging stress at the beginning of the COVID-19 pandemic. The patient suffered from childhood on from ruminative thinking and depressive mood, which was treated in several settings during his life. He started to use alcohol to control his depression, but developed an alcohol addiction. This was successfully treated and the patient remained abstinent for more than 25 years afterwards. About 7 years ago, he started to use Kratom 3–4 times daily on a regular, but constant rate. Kratom use worked efficiently as a self-management of his depression with no escalation of dosing. It was also very effective in reducing Morbus Menière symptoms of tinnitus and sudden hearing loss, which eventually allowed regular performance as a caregiver in a demanding job on shift-work. During recently increased stress load in the work environment and the COVID-19 pandemic, the established Kratom doses failed to control hyperarousal and mental nervousness. The patient was treatment seeking and subsequently detoxified from Kratom. Anxiety- and depression management was shifted to treatment attempts with Lorazepam, Venlafaxine, Opipramol, Mirtazapine and psychotherapy.

Conclusion

Kratom instrumentalization for self-management of depression and anxiety may effectively work without causing escalation of drug use and addiction, but may be limited by a temporary increase in psychological stress load and a relapse into major depression and generalized anxiety disorder.

Proteomic analysis reveals brain Rab35 as a potential biomarker of mitragynine withdrawal in rats

Mitragyna speciosa, also known as kratom, has been used for mitigating the severity of opioid withdrawal in humans. Its main indole alkaloid, mitragynine, has been considered as a pharmacotherapy for pain conditions and opioid replacement therapy. However, at high doses, chronic mitragynine may also have an addiction potential. The effects of chronic action of mitragynine in the brain are still unknown. The present study developed a mitragynine withdrawal model in rats and used it for a proteomic analysis of mitragynine withdrawal effects. Mitragynine (30 mg/kg, i.p.) was administered daily over a period of 14 days and then withdrawn. A proteomic analysis revealed that from a total of 1524 proteins identified, 31 proteins were upregulated, and 3 proteins were downregulated in the mitragynine withdrawal model. The Rab35 protein expression increased most profoundly in the mitragynine withdrawal group as compared to vehicle group. Therefore, it is proposed that Rab35 in the brain might be considered as a potential biomarker during mitragynine withdrawal and might be valuable target protein in developing new pharmacotherapies in the future.

Lyophilized Kratom Tea as a Therapeutic Option for Opioid Dependence

BACKGROUND

Made as a tea, the Thai traditional drug "kratom" reportedly possesses pharmacological actions that include both a coca-like stimulant effect and opium-like depressant effect. Kratom has been used as a substitute for opium in physically-dependent subjects. The objective of this study was to evaluate the antinociception, somatic and physical dependence produced by kratom tea, and then assess if the tea ameliorated withdrawal in opioid physically-dependent subjects.

METHODS

Lyophilized kratom tea (LKT) was evaluated in C57BL/6J and opioid receptor knockout mice after oral administration. Antinociceptive activity was measured in the 55 °C warm-water tail-withdrawal assay. Potential locomotor impairment, respiratory depression and locomotor hyperlocomotion, and place preference induced by oral LKT were assessed in the rotarod, Comprehensive Lab Animal Monitoring System, and conditioned place preference assays, respectively. Naloxone-precipitated withdrawal was used to determine potential physical dependence in mice repeatedly treated with saline or escalating doses of morphine or LKT, and LKT amelioration of morphine withdrawal. Data were analyzed using one- and two-way ANOVA.

RESULTS

Oral administration of LKT resulted in dose-dependent antinociception (≥1 g/kg, p.o.) absent in mice lacking the mu-opioid receptor (MOR) and reduced in mice lacking the kappa-opioid receptor. These doses of LKT did not alter coordinated locomotion or induce conditioned place preference, and only briefly reduced respiration. Repeated administration of LKT did not produce physical dependence, but significantly decreased naloxone-precipitated withdrawal in morphine dependent mice.

CONCLUSIONS

The present study confirms the MOR agonist activity and therapeutic effect of LKT for the treatment of pain and opioid physical dependence.

Kratom instrumentalization for severe pain self-treatment resulting in addiction - A case report of acute and chronic subjective effects

Background

Kratom is a Southeast Asian plant, which is widely used in this region, and making an increasing appearance in Europe and the US.

Case report

We present the case of a 26-year-old man in Substitol-assisted treatment of excessive Kratom and Tilidin use expressing the wish for a drug-free management of a chronic pain condition. After an accidental calcaneus impression fracture, the patient was suffering from severe chronic pain and anxiety of further accidents. This was managed initially with Tilidin. Resulting from the wish to self-manage the pain condition in a way that permitted continuation of a job, the patient searched for a ‘natural’ treatment alternative obtained from an Internet vendor. He successfully instrumentalized Kratom for 3 years with daily consumption intermixed with occasional Tilidin for pain management. However, the dose of Kratom was increased considerably up to a level of effect reversal, when no analgesic and behaviorally activating effects occurred any more, but only intense drowsiness. The patient was treatment seeking and subsequently detoxified from Kratom and Tilidin. Pain management was shifted to retarded morphine.

Conclusion

Kratom instrumentalization for pain management might appear to be more problematic for addiction development than when its use is established for other consumption motives.