Displaying publications 1 - 20 of 33 in total

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  1. Ramanathan S, McCurdy CR
    Curr Opin Psychiatry, 2020 07;33(4):312-318.
    PMID: 32452943 DOI: 10.1097/YCO.0000000000000621
    PURPOSE OF REVIEW: To inform readers about the increasingly popular Western dietary supplement, kratom (Mitragyna speciosa) and how the products are available in the Western world compared with traditional Southeast Asian use. Kratom has been traditionally used for increasing stamina of outdoor laborers (farmers), mood enhancement, pain, and opium addiction. Interestingly, kratom has been reported to have a paradoxical effect in that stimulant feelings, and sedative feelings can be obtained depending on the amount utilized. There are several biologically active alkaloids present in kratom.

    RECENT FINDINGS: Recent studies have been focused on the interactions of mitragynine, the most abundant alkaloid, and opioid-like effects. This has been driven by the harm that kratom products have produced in the Western world, in stark contrast to the lack of harm in Southeast Asian traditional use over centuries. Many users in the Western world ingest kratom for mood enhancement and/or to ween themselves from prescription or illicit opioids. Highly concentrated products and recreational use and misuse have resulted in individuals pushing doses to levels that have not been imagined or ever studied in animal, let alone humans.

    SUMMARY: Kratom, as a preparation and how it is utilized is different around the world.

    Matched MeSH terms: Secologanin Tryptamine Alkaloids/pharmacology*
  2. Tan YS, Ng MP, Tan CH, Tang WK, Sim KS, Yong KT, et al.
    J Nat Prod, 2024 Feb 23;87(2):286-296.
    PMID: 38284153 DOI: 10.1021/acs.jnatprod.3c00960
    Nine new alkaloids, eugeniinalines A-H (1-8) and (+)-eburnamenine N-oxide (9), comprising one quinoline, six indole, and two isogranatanine alkaloids, were isolated from the stem-bark extract of the Malayan Leuconotis eugeniifolia. The structures and absolute configurations of these alkaloids were established based on the analysis of the spectroscopic data, GIAO NMR calculations, DP4+ probability analysis, TDDFT-ECD method, and X-ray diffraction analysis. Eugeniinaline A (1) represents a new pentacyclic quinoline alkaloid with a 6/6/5/6/7 ring system. Eugeniinaline G (7) and its seco-derivative, eugeniinaline H (8), were the first isogranatanine alkaloids isolated as natural products. The known alkaloids leucolusine (10) and melokhanine A (11) were found to be the same compound, based on comparison of the spectroscopic data of both compounds, with the absolute configuration of (7R, 20R, 21S). Eugeniinalines A and G (1 and 7) showed cytotoxic activity against the HT-29 cancer cell line with IC50 values of 7.1 and 7.2 μM, respectively.
    Matched MeSH terms: Secologanin Tryptamine Alkaloids/pharmacology
  3. Begum T, Arzmi MH, Khatib A, Uddin ABMH, Aisyah Abdullah M, Rullah K, et al.
    Nat Prod Res, 2025 Mar;39(6):1636-1652.
    PMID: 38923960 DOI: 10.1080/14786419.2024.2371564
    Mitragyna speciosa Korth (kratom) is a tropical indigenous tree of Southeast Asia. It is commonly consumed by the people due to its various pharmacological properties. The leaves of this plant are traditionally used for the treatment of several diseases including pain, fever, cough, anxiety, depression, obesity, diarrhoea, wound healing, diabetes, hypertension as well as for the prevention of cancer and improvement of sexual performance. Phytochemical investigations have confirmed the presence of more than forty alkaloids along with the presence of other bioactive secondary metabolites. Among the alkaloids isolated, mitragynine and 7-hydroxymitragynine along with their derivatives have been widely evaluated and reported to possess various pharmacological effects. Hence, the aim of this review is to shed light on the traditional uses of kratom and the scientific studies to justify the folkloric claims and active principles responsible for the various medicinal effects associated with the leaves of this plant. This review highlights the potential benefits and toxicities associated with M. speciosa leaves along with the phytochemistry. Moreover, the existing gaps in the field of M. speciosa study have been identified along with the future directions to further avail the benefits of this plant species.
    Matched MeSH terms: Secologanin Tryptamine Alkaloids/pharmacology
  4. Müller CP, Yang Y, Singh D, Lenz B, Müller E
    Nervenarzt, 2024 Sep;95(9):824-829.
    PMID: 39085520 DOI: 10.1007/s00115-024-01721-6
    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.

    Matched MeSH terms: Secologanin Tryptamine Alkaloids/pharmacology
  5. Rusli N, Amanah A, Kaur G, Adenan MI, Sulaiman SF, Wahab HA, et al.
    Naunyn Schmiedebergs Arch Pharmacol, 2019 04;392(4):481-496.
    PMID: 30604191 DOI: 10.1007/s00210-018-01605-y
    Mitragynine is a major component isolated from Mitragyna speciosa Korth or kratom, a medicinal plant known for its opiate-like and euphoric properties. Multiple toxicity and fatal cases involving mitragynine or kratom have been reported but the underlying causes remain unclear. P-glycoprotein (P-gp) is a multidrug transporter which modulates the pharmacokinetics of xenobiotics and plays a key role in mediating drug-drug interactions. This study investigated the effects of mitragynine on P-gp transport activity, mRNA, and protein expression in Caco-2 cells using molecular docking, bidirectional assay, RT-qPCR, Western blot analysis, and immunocytochemistry techniques, respectively. Molecular docking simulation revealed that mitragynine interacts with important residues at the nucleotide binding domain (NBD) site of the P-gp structure but not with the residues from the substrate binding site. This was consistent with subsequent experimental work as mitragynine exhibited low permeability across the cell monolayer but inhibited digoxin transport at 10 μM, similar to quinidine. The reduction of P-gp activity in vitro was further contributed by the downregulation of mRNA and protein expression of P-gp. In summary, mitragynine is likely a P-gp inhibitor in vitro but not a substrate. Hence, concurrent administration of mitragynine-containing kratom products with psychoactive drugs which are P-gp substrates may lead to clinically significant toxicity. Further clinical study to prove this point is needed.
    Matched MeSH terms: Secologanin Tryptamine Alkaloids/pharmacology*
  6. Tay YL, Amanah A, Adenan MI, Wahab HA, Tan ML
    Sci Rep, 2019 12 24;9(1):19757.
    PMID: 31874991 DOI: 10.1038/s41598-019-56106-6
    Mitragyna speciosa Korth (M. speciosa) has been widely used as a recreational product, however, there are growing concerns on the abuse potentials and toxicity of the plant. Several poisoning and fatal cases involving kratom and mitragynine have been reported but the underlying causes remain unclear. The human ether-a-go-go-related gene 1 (hERG1) encodes the pore-forming subunit underlying cardiac rapidly delayed rectifier potassium current (IKr). Pharmacological blockade of the IKr can cause acquired long QT syndrome, leading to lethal cardiac arrhythmias. This study aims to elucidate the mechanisms of mitragynine-induced inhibition on hERG1a/1b current. Electrophysiology experiments were carried out using Port-a-Patch system. Quantitative RT-PCR, Western blot analysis, immunofluorescence and co-immunoprecipitation methods were used to determine the effects of mitragynine on hERG1a/1b expression and hERG1-cytosolic chaperones interaction. Mitragynine was found to inhibit the IKr current with an IC50 value of 332.70 nM. It causes a significant reduction of the fully-glycosylated (fg) hERG1a protein expression but upregulates both core-glycosylated (cg) expression and hERG1a-Hsp90 complexes, suggesting possible impaired hERG1a trafficking. In conclusion, mitragynine inhibits hERG1a/1b current through direct channel blockade at lower concentration, but at higher concentration, it upregulates the complexation of hERG1a-Hsp90 which may be inhibitory towards channel trafficking.
    Matched MeSH terms: Secologanin Tryptamine Alkaloids/pharmacology*
  7. Jansen KL, Prast CJ
    J Psychoactive Drugs, 1988 Oct-Dec;20(4):455-7.
    PMID: 3072396
    Matched MeSH terms: Secologanin Tryptamine Alkaloids/pharmacology
  8. Chear NJ, León F, Sharma A, Kanumuri SRR, Zwolinski G, Abboud KA, et al.
    J Nat Prod, 2021 04 23;84(4):1034-1043.
    PMID: 33635670 DOI: 10.1021/acs.jnatprod.0c01055
    Ten indole and oxindole alkaloids (1-10) were isolated from the freshly collected leaves of Malaysian Mitragyna speciosa (Kratom). The chemical structures of these compounds were established on the basis of extensive 1D and 2D NMR and HRMS data analysis. The spectroscopic data of mitragynine oxindole B (4) are reported herein for the first time. The spatial configuration of mitragynine oxindole B (4) was confirmed by single-crystal X-ray diffraction. Simultaneous quantification of the isolated alkaloids in the M. speciosa leaf specimens collected from different locations in the northern region of Peninsular Malaysia was also performed using UPLC-MS/MS. The oxindole alkaloids (1-4) and the indole alkaloid (10) were assessed for binding affinity at opioid receptors. Corynoxine (1) showed high binding affinity to μ-opioid receptors with a Ki value of 16.4 nM. Further, corynoxine (1) was 1.8-fold more potent than morphine in rats subjected to a nociceptive hot plate assay. These findings have important implications for evaluating the combined effects of the minor oxindole alkaloids in the overall therapeutic activity of M. speciosa.
    Matched MeSH terms: Secologanin Tryptamine Alkaloids/pharmacology
  9. Liew SY, Khaw KY, Murugaiyah V, Looi CY, Wong YL, Mustafa MR, et al.
    Phytomedicine, 2015 Jan 15;22(1):45-8.
    PMID: 25636869 DOI: 10.1016/j.phymed.2014.11.003
    Nine monoterpenoid indole alkaloids; naucletine (1), angustidine (2), nauclefine (3), angustine (4), naucline (5), angustoline (6), harmane (7), 3,14-dihydroangustoline (8), strictosamide (9) and one quinoline alkaloid glycoside; pumiloside (10) from Nauclea officinalis were tested for cholinesterase inhibitory activity. All the alkaloids except for pumiloside (10) showed strong to weak BChE inhibitory effect with IC50 values ranging between 1.02-168.55 μM. Angustidine (2), nauclefine (3), angustine (4), angustoline (6) and harmane (7) showed higher BChE inhibiting potency compared to galanthamine. Angustidine (2) was the most potent inhibitor towards both AChE and BChE. Molecular docking (MD) studies showed that angustidine (2) docked deep into the bottom gorge of hBChE and formed hydrogen bonding with Ser 198 and His 438. Kinetic study of angustidine (2) on BChE suggested a mixed inhibition mode with an inhibition constant (Ki) of 6.12 μM.
    Matched MeSH terms: Secologanin Tryptamine Alkaloids/pharmacology*
  10. Ismail NIW, Jayabalan N, Mansor SM, Müller CP, Muzaimi M
    Addict Biol, 2017 Jul;22(4):967-976.
    PMID: 26990882 DOI: 10.1111/adb.12385
    Kratom (Mitragyna speciosa) is a widely abused herbal drug preparation in Southeast Asia. It is often consumed as a substitute for heroin, but imposing itself unknown harms and addictive burdens. Mitragynine is the major psychostimulant constituent of kratom that has recently been reported to induce morphine-like behavioural and cognitive effects in rodents. The effects of chronic consumption on non-drug related behaviours are still unclear. In the present study, we investigated the effects of chronic mitragynine treatment on spontaneous activity, reward-related behaviour and cognition in mice in an IntelliCage® system, and compared them with those of morphine and Δ-9-tetrahydrocannabinol (THC). We found that chronic mitragynine treatment significantly potentiated horizontal exploratory activity. It enhanced spontaneous sucrose preference and also its persistence when the preference had aversive consequences. Furthermore, mitragynine impaired place learning and its reversal. Thereby, mitragynine effects closely resembled that of morphine and THC sensitisation. These findings suggest that chronic mitragynine exposure enhances spontaneous locomotor activity and the preference for natural rewards, but impairs learning and memory. These findings confirm pleiotropic effects of mitragynine (kratom) on human lifestyle, but may also support the recognition of the drug's harm potential.
    Matched MeSH terms: Secologanin Tryptamine Alkaloids/pharmacology*
  11. Prozialeck WC, Avery BA, Boyer EW, Grundmann O, Henningfield JE, Kruegel AC, et al.
    Int J Drug Policy, 2019 08;70:70-77.
    PMID: 31103778 DOI: 10.1016/j.drugpo.2019.05.003
    Kratom (Mitragyna speciosa) is a tree-like plant indigenous to Southeast Asia. Its leaves, and the teas brewed from them have long been used by people in that region to stave off fatigue and to manage pain and opioid withdrawal. Evidence suggests kratom is being increasingly used by people in the United States and Europe for the self-management of opioid withdrawal and treatment of pain. Recent studies have confirmed that kratom and its chemical constituents have potentially useful pharmacological actions. However, there have also been increasing numbers of reports of adverse effects resulting from use of kratom products. In August 2016, the US Drug Enforcement Administration announced plans to classify kratom and its mitragynine constituents as Schedule I Controlled Substances, a move that triggered a massive response from pro-kratom advocates. The debate regarding the risks, and benefits and safety of kratom continues to intensify. Kratom proponents tout kratom as a safer and less addictive alternative to opioids for the management of pain and opioid addiction. The anti-kratom faction argues that kratom, itself, is a dangerous and addictive drug that ought to be banned. Given the widespread use of kratom and the extensive media attention it is receiving, it is important for physicians, scientists and policy makers to be knowledgeable about the subject. The purpose of this commentary is to update readers about recent developments and controversies in this rapidly evolving area. All of the authors are engaged in various aspects of kratom research and it is our intention to provide a fair and balanced overview that can form the basis for informed decisions on kratom policy. Our conclusions from these analyses are: (a) User reports and results of preclinical studies in animals strongly suggest that kratom and its main constituent alkaloid, mitragynine may have useful activity in alleviating pain and managing symptoms of opioid withdrawal, even though well-controlled clinical trials have yet to be done. (b) Even though kratom lacks many of the toxicities of classic opioids, there are legitimate concerns about the safety and lack of quality control of purported "kratom" products that are being sold in the US. (c) The issues regarding the safety and efficacy of kratom and its mitragynine constituent can only be resolved by additional research. Classification of the Mitragyna alkaloids as Schedule I controlled substances would substantially impede this important research on kratom.
    Matched MeSH terms: Secologanin Tryptamine Alkaloids/pharmacology
  12. Obeng S, Kamble SH, Reeves ME, Restrepo LF, Patel A, Behnke M, et al.
    J Med Chem, 2020 01 09;63(1):433-439.
    PMID: 31834797 DOI: 10.1021/acs.jmedchem.9b01465
    Selected indole-based kratom alkaloids were evaluated for their opioid and adrenergic receptor binding and functional effects, in vivo antinociceptive effects, plasma protein binding, and metabolic stability. Mitragynine, the major alkaloid in Mitragyna speciosa (kratom), had higher affinity at opioid receptors than at adrenergic receptors while the vice versa was observed for corynantheidine. The observed polypharmacology of kratom alkaloids may support its utilization to treat opioid use disorder and withdrawal.
    Matched MeSH terms: Secologanin Tryptamine Alkaloids/pharmacology*
  13. Apryani E, Hidayat MT, Moklas MA, Fakurazi S, Idayu NF
    J Ethnopharmacol, 2010 Jun 16;129(3):357-60.
    PMID: 20371280 DOI: 10.1016/j.jep.2010.03.036
    AIM OF THE STUDY: Mitragyna speciosa Korth from Rubiaceae family is a tropical plant indigenous to Southeast Asia particularly in Thailand, Peninsular of Malaysia and Indonesia. The leaves have been used by natives for their opium-like effect and cocaine-like stimulant ability to combat fatigue and enhance tolerance to hard work. However there is no scientific information about the effect of mitragynine on the cognitive performances. This study is designed to examine the working memory effects of mitragynine which is extracted from Mitragyna speciosa mature leaves.

    MATERIALS AND METHODS: The cognitive effect was studied using object location task and the motor activity in open-field test. Mitragynine 5, 10 and 15 mg/kg and were administered by intraperitoneal (IP) for 28 consecutive days and evaluated on day 28 after the last dose treatment. Scopolamine was used as the control positive drug.

    RESULTS: In this study there is prominent effects on horizontal locomotor activity was observed. Mitragynine significantly reduced locomotor activity in open-field test compared with vehicle. In object location task mitragynine (5, 10 and 15 mg/kg) did not showed any significances discrimination between the object that had changed position than the object that had remain in a constant position.

    CONCLUSION: Our results suggest that chronic administration of mitragynine can altered the cognitive behavioral function in mice.

    Matched MeSH terms: Secologanin Tryptamine Alkaloids/pharmacology*
  14. Lim SH, Sim KM, Abdullah Z, Hiraku O, Hayashi M, Komiyama K, et al.
    J Nat Prod, 2007 Aug;70(8):1380-3.
    PMID: 17608533
    Four new indole alkaloids were obtained from two Kopsia species, 6-oxoleuconoxine (1) from the leaf extract of K. griffithii and kopsinitarine E (2), kopsijasminine (3), and kopsonoline (4) from the stem-bark extract of K. teoi. The structures of these alkaloids were determined using NMR and MS analysis. Kopsijasminine (3) showed moderate activity in reversing multidrug resistance in vincristine-resistant KB cells.
    Matched MeSH terms: Secologanin Tryptamine Alkaloids/pharmacology
  15. Takayama H
    Chem Pharm Bull (Tokyo), 2004 Aug;52(8):916-28.
    PMID: 15304982
    The leaves of a tropical plant, Mitragyna speciosa KORTH (Rubiaceae), have been traditionally used as a substitute for opium. Phytochemical studies of the constituents of the plant growing in Thailand and Malaysia have led to the isolation of several 9-methoxy-Corynanthe-type monoterpenoid indole alkaloids, including new natural products. The structures of the new compounds were elucidated by spectroscopic and/or synthetic methods. The potent opioid agonistic activities of mitragynine, the major constituent of this plant, and its analogues were found in in vitro and in vivo experiments and the mechanisms underlying the analgesic activity were clarified. The essential structural features of mitragynines, which differ from those of morphine and are responsible for the analgesic activity, were elucidated by pharmacological evaluation of the natural and synthetic derivatives. Among the mitragynine derivatives, 7-hydroxymitragynine, a minor constituent of M. speciosa, was found to exhibit potent antinociceptive activity in mice.
    Matched MeSH terms: Secologanin Tryptamine Alkaloids/pharmacology
  16. Singh D, Müller CP, Vicknasingam BK, Mansor SM
    J Psychoactive Drugs, 2015 5 8;47(2):125-31.
    PMID: 25950592 DOI: 10.1080/02791072.2015.1012610
    Kratom (Mitragyna speciosa) is an indigenous plant known for its traditional medicinal use, and for its addiction potential, in Southeast Asia. In recent years, kratom and its major alkaloid, mitragynine, spread worldwide with largely unknown effects on behavior and mental health. Recent studies show that kratom use can lead to dependence and that mitragynine works as an addictive drug in animal studies. Nevertheless, kratom preparations were also suggested as a less harmful substitute in opiate withdrawal. Potential side-effects of prolonged kratom use, however, are currently unclear. The aim of this study was to investigate the social functioning of regular kratom users in Malaysia. A cross-sectional survey was carried out in three northern states of Peninsular Malaysia investigating 293 regular kratom consumers using the Addiction Severity Index in a snowball sampling technique. Findings showed that regular kratom users do not experience major impairments in their social functioning, despite being dependent on kratom for prolonged periods. Our findings suggest that chronic kratom administration does not significantly impair social functioning of users in a natural context in Malaysia.
    Matched MeSH terms: Secologanin Tryptamine Alkaloids/pharmacology*
  17. Tay YL, Teah YF, Chong YM, Jamil MFA, Kollert S, Adenan MI, et al.
    Toxicol Appl Pharmacol, 2016 08 15;305:22-39.
    PMID: 27260674 DOI: 10.1016/j.taap.2016.05.022
    Mitragyna speciosa Korth is known for its euphoric properties and is frequently used for recreational purposes. Several poisoning and fatal cases involving mitragynine have been reported but the underlying causes remain unclear. Human ether-a-go-go-related gene (hERG) encodes the cardiac IKr current which is a determinant of the duration of ventricular action potentials and QT interval. On the other hand, IK1, a Kir current mediated by Kir2.1 channel and IKACh, a receptor-activated Kir current mediated by GIRK channel are also known to be important in maintaining the cardiac function. This study investigated the effects of mitragynine on the current, mRNA and protein expression of hERG channel in hERG-transfected HEK293 cells and Xenopus oocytes. The effects on Kir2.1 and GIRK channels currents were also determined in the oocytes. The hERG tail currents following depolarization pulses were inhibited by mitragynine with an IC50 value of 1.62μM and 1.15μM in the transfected cell line and Xenopus oocytes, respectively. The S6 point mutations of Y652A and F656A attenuated the inhibitor effects of mitragynine, indicating that mitragynine interacts with these high affinity drug-binding sites in the hERG channel pore cavity which was consistent with the molecular docking simulation. Interestingly, mitragynine does not affect the hERG expression at the transcriptional level but inhibits the protein expression. Mitragynine is also found to inhibit IKACh current with an IC50 value of 3.32μM but has no significant effects on IK1. Blocking of both hERG and GIRK channels may cause additive cardiotoxicity risks.
    Matched MeSH terms: Secologanin Tryptamine Alkaloids/pharmacology*
  18. Kong WM, Chik Z, Mohamed Z, Alshawsh MA
    PMID: 29076424 DOI: 10.2174/1386207320666171026121820
    AIM AND OBJECTIVE: Mitragynine, a major active alkaloid of Mitragyna speciosa, acts as an agonist on µ-opioid receptors, producing effects similar to morphine and other opioids. It has been traditionally utilized to alleviate opiate withdrawal symptoms. Besides consideration about potency and selectivity, a good drug must possess a suitable pharmacokinetic profile, with suitable absorption, distribution, metabolism, excretion and toxicity (ADME-Tox) profile, in order to have a high chance of success in clinical trials.

    MATERIAL AND METHOD: The purity of mitragynine in a Mitragyna speciosa alkaloid extract (MSAE) was determined using Ultra-Fast Liquid Chromatography (UFLC). In vitro high throughput ADMETox studies such as aqueous solubility, plasma protein binding, metabolic stability, permeability and cytotoxicity tests were carried out to analyze the physicochemical properties of MSAE and mitragynine. The UFLC quantification revealed that the purity of mitragynine in the MSAE was 40.9%.

    RESULTS: MSAE and mitragynine are highly soluble in aqueous solution at pH 4.0 but less soluble at pH 7.4. A parallel artificial membrane permeability assay demonstrated that it is extensively absorbed through the semi-permeable membrane at pH 7.4 but very poorly at pH 4.0. Both are relatively highly bound to plasma proteins (> 85 % bound) and are metabolically stable to liver microsomes (> 84 % remained unchanged). In comparison to MSAE, mitragynine showed higher cytotoxicity against WRL 68, HepG2 and Clone 9 hepatocytes after 72 h treatment.

    CONCLUSION: The obtained ADME and cytotoxicity data demonstrated that both MSAE and mitragynine have poor bioavailability and have the potential to be significantly cytotoxic.

    Matched MeSH terms: Secologanin Tryptamine Alkaloids/pharmacology*
  19. Yusoff NHM, Mansor SM, Müller CP, Hassan Z
    Behav Brain Res, 2018 06 01;345:65-71.
    PMID: 29499286 DOI: 10.1016/j.bbr.2018.02.039
    Mitragynine is the major alkaloid found in the leaves of M. speciosa Korth (Rubiaceae), a plant that is native to Southeast Asia. This compound has been used, either traditionally or recreationally, due to its psychostimulant and opioid-like effects. Recently, mitragynine has been shown to exert conditioned place preference (CPP), indicating the rewarding and motivational properties of M. speciosa. Here, the involvement of GABAB receptors in mediating mitragynine reward is studied using a CPP paradigm in rats. First, we examined the effects of GABAB receptor agonist baclofen (1.25, 2.5 and 5 mg/kg) on the acquisition of mitragynine (10 mg/kg)-induced CPP. Second, the involvement of GABAB receptors in the expression of mitragynine-induced CPP was tested. We found that the acquisition of mitragynine-induced CPP could be blocked by higher doses (2.5 and 5 mg/kg) of baclofen. Baclofen at a high dose inhibited locomotor activity and caused a CPP. Furthermore, we found that baclofen (2.5 and 5 mg/kg) also blocked the expression of mitragynine-induced CPP. These findings suggest that both, the acquisition and expression of mitragynine's reinforcing properties is controlled by the GABAB receptor.
    Matched MeSH terms: Secologanin Tryptamine Alkaloids/pharmacology*
  20. Japarin RA, Yusoff NH, Hassan Z, Müller CP, Harun N
    Behav Brain Res, 2021 02 05;399:113021.
    PMID: 33227244 DOI: 10.1016/j.bbr.2020.113021
    Kratom is a medicinal plant that exhibits promising results as an opiate substitute. However, there is little information regarding the abuse profile of its main psychoactive constituent, mitragynine (MG), particularly in relapse to drug abuse. Using the place conditioning procedure as a model of relapse, this study aims to evaluate the ability of MG to induce conditioned place preference (CPP) reinstatement in rats. To evaluate the cross-reinstatement effects, MG and morphine were injected to rats that previously extinguished a morphine- or MG-induced CPP. Following a CPP acquisition induced by either MG (10 and 30 mg/kg, i.p.) or morphine (10 mg/kg, i.p.), rats were subjected to repeated CPP extinction sessions. A low dose priming injection of MG or morphine produced a reinstatement of the previously extinguished CPP. In the second experiment of this study, a priming injection of morphine (1, 3 and 10 mg/kg, i.p.) dose-dependently reinstated an MG-induced CPP. Likewise, a priming injection of MG (3, 10 and 30 mg/kg, i.p.) was able to dose-dependently reinstate a morphine-induced CPP. The present study demonstrates a cross-reinstatement effect between MG and morphine, thereby suggesting a similar interaction in their rewarding motivational properties. The findings from this study also suggesting that a priming exposure to kratom and an opioid may cause relapse for a previously abused drug.
    Matched MeSH terms: Secologanin Tryptamine Alkaloids/pharmacology*
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