5-Methoxy-N,N-diisopropyltryptamine (Foxy), a selective and high affinity inhibitor of serotonin transporter

Structure-activity relationships of serotonergic 5-MeO-DMT derivatives: insights into psychoactive and thermoregulatory properties

Recent studies have sparked renewed interest in the therapeutic potential of psychedelics for treating depression and other mental health conditions. Simultaneously, the novel psychoactive substances (NPS) phenomenon, with a huge number of NPS emerging constantly, has changed remarkably the illicit drug market, being their scientific evaluation an urgent need. Thus, this study aims to elucidate the impact of amino-terminal modifications to the 5-MeO-DMT molecule on its interactions with serotonin receptors and transporters, as well as its psychoactive and thermoregulatory properties. Our findings demonstrated, using radioligand binding methodologies, that all examined 5-MeO-tryptamines exhibited selectivity for 5-HT1AR over 5-HT2AR. In fact, computational docking analyses predicted a better interaction in the 5-HT1AR binding pocket compared to 5-HT2AR. Our investigation also proved the interaction of these compounds with SERT, revealing that the molecular size of the amino group significantly influenced their affinity. Subsequent experiments involving serotonin uptake, electrophysiology, and superfusion release assays confirmed 5-MeO-pyr-T as the most potent partial 5-HT releaser tested. All tested tryptamines elicited, to some degree, the head twitch response (HTR) in mice, indicative of a potential hallucinogenic effect and mainly mediated by 5-HT2AR activation. However, 5-HT1AR was also shown to be implicated in the hallucinogenic effect, and its activation attenuated the HTR. In fact, tryptamines that produced a higher hypothermic response, mediated by 5-HT1AR, tended to exhibit a lower hallucinogenic effect, highlighting the opposite role of both 5-HT receptors. Moreover, although some 5-MeO-tryptamines elicited very low HTR, they still act as potent 5-HT2AR agonists. In summary, this research offers a comprehensive understanding of the psychopharmacological profile of various amino-substituted 5-MeO-tryptamines, keeping structural aspects in focus and accumulating valuable data in the frame of NPS. Moreover, the unique characteristics of some 5-MeO-tryptamines render them intriguing molecules as mixed-action drugs and provide insight within the search of non-hallucinogenic but 5-HT2AR ligands as therapeutical agents.

Effects of Ketanserin, M100907 and Olanzapine on hallucinogenic like action induced by 2,5-dimethoxy-4-methylamphetamine

2,5-dimethoxy-4-methylamphetamine (DOM) is a kind of hallucinogen of phenylalkylamine. Psychedelic effects mainly include audiovisual synesthesia, complex imagery, disembodiment etc. that can impair control and cognition leading to adverse consequences such as suicide. By now, there are no specific drugs regarding the management of classic hallucinogen use clinically. We evaluated the effects of three 5-HT 2A receptor antagonists ketanseirn, M100907 and olanzapine on hallucination-like behavior in therapeutic and preventive administration with male C57BL/6J mice. Two models were used to evaluate the therapeutic potential of antagonists, one is head-twitch response (HTR) and the other is locomotion. Effects of ketanserin, M100907 and olanzapine on DOM-induced HTR were studied in preventive and therapeutic administration, respectively. In the preventive administration, the ID 50 values of ketanseirn, M100907 and olanzapine were 0.4 mg/kg, 0.005 mg/kg and 0.25 mg/kg. In the therapeutic administration, the ID 50 values of ketanseirn, M100907 and olanzapine were 0.04 mg/kg, 0.005 mg/kg and 0.03 mg/kg. Secondly, locomotor activity induced by DOM was performed to further evaluate the efficacy of three compounds. In locomotion, M100907(0.005 mg/kg) whenever in preventive or therapeutic administration, reduced the increase of movement distance induced by DOM. Although ketanserin (0.4 mg/kg) in the preventive administration also decreased the movement distance induced by DOM, it was alone administrated to influence the locomotor activity. Through HTR and locomotion, we compared the efficacy and latent side effects of ketanserin, M100907 and olanzapine against hallucinogenic like action induced by DOM. Our study provided additional experimental evidence on specific therapeutic drugs against hallucinogenic behavior induce by representative hallucinogen DOM.

Mobile Health Technology Use and the Acceptability of an mHealth Platform for HIV Prevention Among Men Who Have Sex With Men in Malaysia: Cross-sectional Respondent-Driven Sampling Survey

BACKGROUND

The growth in mobile technology access, utilization, and services holds great promise in facilitating HIV prevention efforts through mobile health (mHealth) interventions in Malaysia. Despite these promising trends, there is a dearth of evidence on the use of mHealth platforms that addresses HIV prevention among Malaysian men who have sex with men.

OBJECTIVE

The goal of this study was to gain insight into (1) access and utilization of communication technology (eg, landline phone, internet, mobile phone), (2) acceptability of mHealth-based interventions for HIV prevention services, and (3) preferences regarding the format and frequency of mHealth interventions among Malaysian men who have sex with men.

METHODS

We conducted a cross-sectional survey with Malaysian men who have sex with men between July 2018 and March 2020. Participants were recruited using respondent-driven sampling in the Greater Kuala Lumpur region of Malaysia. We collected information on demographic characteristics, HIV risk-related behaviors, access to and the frequency of use of communication technology, and acceptability of using mHealth for HIV prevention using a self-administered questionnaire with a 5-point scale (1, never; 2, rarely; 3, sometimes; 4, often; 5, all the time).

RESULTS

A total of 376 men participated in the survey. Almost all respondents owned or had access to a smartphone with internet access (368/376, 97.9%) and accessed the internet daily (373/376, 99.2%), mainly on a smartphone (334/376, 88.8%). Participants on average used smartphones primarily for social networking (mean 4.5, SD 0.8), followed by sending or receiving emails (mean 4.0, SD 1.0), and searching for health-related information (mean 3.5, SD 0.9). There was high acceptance of the use of mHealth for HIV prevention (mean 4.1, SD 1.5), including for receiving HIV prevention information (345/376, 91.8%), receiving medication reminders (336/376, 89.4%), screening and monitoring sexual activity (306/376, 81.4%) or illicit drug use (281/376, 74.7%), and monitoring drug cravings (280/376, 74.5%). Participants overwhelmingly preferred a smartphone app over other modalities (eg, text, phone call, email) for engaging in mHealth HIV prevention tools. Preference for app notifications ranged from 186/336 (53.9%), for receiving HIV prevention information, to 212/336 (69.3%), for screening and monitoring sexual activity. Acceptance of mHealth was higher for those who were university graduates (P=.003), living in a relationship with a partner (P=.04), engaged in sexualized drug use (P=.01), and engaged in receptive anal sex (P=.006).

CONCLUSIONS

Findings from this study provide support for developing and deploying mHealth strategies for HIV prevention using a smartphone app in men who have sex with men-a key population with suboptimal engagement in HIV prevention and treatment.

Reports of Adverse Events Associated with Use of Novel Psychoactive Substances, 2017-2020: A Review

An important role of modern forensic and clinical toxicologists is to monitor the adverse events of novel psychoactive substances (NPS). Following a prior review from 2013 to 2016, this critical literature review analyzes and evaluates published case reports for NPS from January 2017 through December 2020. The primary objective of this study is to assist in the assessment and interpretation of these cases as well as provide references for confirmation methods. Chemistry, pharmacology, adverse events and user profiles (e.g., polypharmacy) for NPS are provided including case history, clinical symptoms, autopsy findings and analytical results. Literature reviews were performed in PubMed and Google Scholar for publications using search terms such as NPS specific names, general terms (e.g., 'designer drugs' and 'novel psychoactive substances'), drug classes (e.g., 'designer stimulants') and outcome-based terms (e.g., 'overdose' and 'death'). Government and website drug surveillance databases and abstracts published by professional forensic science organizations were also searched. Toxicological data and detailed case information were extracted, tabulated, analyzed and organized by drug category. Case reports included overdose fatalities (378 cases), clinical treatment and hospitalization (771 cases) and driving under the influence of drugs (170 cases) for a total of 1,319 cases providing details of adverse events associated with NPS. Confirmed adverse events with associated toxidromes of more than 60 NPS were reported including synthetic cannabinoid, NPS stimulant, NPS hallucinogen, NPS benzodiazepine and NPS opioid cases. Fifty of these NPS were reported for the first time in January 2017 through December 2020 as compared to the previous 4 years surveyed. This study provides insight and context of case findings described in the literature and in digital government surveillance databases and websites during a recent 4-year period. This review will increase the awareness of adverse events associated with NPS use to better characterize international emerging drug threats.

Dual actions of 5-MeO-DIPT at the serotonin transporter and serotonin 5-HT1A receptor in the mouse striatum and prefrontal cortex

Aims

5‐Methoxy‐N,N‐diisopropyltryptamine (5‐MeO‐DIPT) is a synthetic orally active hallucinogenic tryptamine analogue. The present study examined whether the effects of 5‐MeO‐DIPT involve the serotonin transporter (SERT) and serotonin 5‐hydroxytryptamine‐1A (5‐HT_1A) receptor in the striatum and prefrontal cortex (PFC).

Methods

We investigated the effects of 5‐MeO‐DIPT on extracellular 5‐HT (5‐HT_ex) and dopamine (DA_ex) levels in the striatum and PFC in wildtype and SERT knockout (KO) mice using in vivo microdialysis, and for comparison the effects of the 5‐HT_1A receptor antagonist WAY100635 and the 5‐HT_1A receptor agonist 8‐OH‐DPAT on 5‐HT_ex.

Results

5‐MeO‐DIPT decreased 5‐HT_ex levels in the striatum, but not PFC. In SERT‐KO mice, 5‐MeO‐DIPT did not affect 5‐HT_ex levels in the striatum or PFC. In the presence of WAY100635, 5‐MeO‐DIPT substantially increased 5‐HT_ex levels, suggesting that 5‐MeO‐DIPT acts on SERT and these effects are masked by its 5‐HT_1A actions in the absence of WAY100635. 8‐OH‐DPAT decreased 5‐HT_ex levels in the striatum and PFC in wildtype mice. WAY100635 antagonized the 8‐OH‐DPAT‐induced decrease in 5‐HT_ex levels. In SERT‐KO mice, 8‐OH‐DPAT did not decrease 5‐HT_ex levels in the striatum and PFC. 5‐MeO‐DIPT dose‐dependently increased DA_ex levels in the PFC, but not striatum, in wildtype and SERT‐KO mice. The increase in DA_ex levels that was induced by 5‐MeO‐DIPT was not antagonized by WAY100635.

Conclusion

5‐MeO‐DIPT influences both 5‐HT_ex and DA_ex levels in the striatum and PFC. 5‐MeO‐DIPT dually acts on SERT and 5‐HT_1A receptors so that elevations in 5‐HT_ex levels produced by reuptake inhibition are limited by actions of the drug on 5‐HT_1A receptors.

5‐MeO‐DIPT influences both 5‐HT_ex and DA_ex levels in the striatum and PFC. 5‐MeO‐DIPT dually acts on SERT and 5‐HT1A receptors so that elevations in 5‐HT_ex levels produced by reuptake inhibition are limited by actions of the drug on 5‐HT_1A receptors.

The effect of repeated-intermittent exposure to 5-methoxy-N,N-diisopropyltryptamine (5-MeO-DIPT) during adolescence on learning and memory in adult rats

BACKGROUND

According to the European Drug Report, the use of novel psychoactive substances (NPS) is constantly growing. NPS are widely abused by human adolescent subjects. 5-Methoxy-N,N-diisopropyltryptamine (5-MeO-DIPT) is one of the most frequently used hallucinogenic NPS. 5-MeO-DIPT intoxication results in hallucinations, vomiting, and tachycardia. Long-term exposure to 5-MeO-DIPT was reported to lead to development of post-hallucinogenic perception disorder. The aim of the present study was to determine whether repeated-intermittent administration of 5-MeO-DIPT during adolescence affects learning and memory in adult rats.

METHODS

Rats were treated with 5-MeO-DIPT in a dose of 2.5 mg/kg from 30 to 33 and 37 to 40 Postnatal Day (PND). The experiments were conducted when the animals reached 90 PND. The effect of 5-MeO-DIPT on cognitive functions was assessed using the novel object recognition, open field, and serial pattern learning (SPL) tests.

RESULTS

Repeated-intermittent exposure to 5-MeO-DIPT during adolescence decreased the number of crossings in the open field test at adulthood. Moreover, 5-MeO-DIPT treatment impaired adult rats' learning in the SPL test. There was no change in the novel object recognition test.

CONCLUSIONS

The present results show that the performance of adult rats treated with 5-MeO-DIPT during adolescence was impaired in the open field test, which indicates the attenuated exploratory activity. 5-MeO-DIPT treatment undermined adult rats' performance in the serial pattern learning test, suggesting impairment of long term memory and cognitive flexibility. The present study showed that the exposure to 5-MeO-DIPT during adolescence might lead to long-lasting behavioral changes which persisted long after the exposure period.

Effects of exposure to 5-MeO-DIPT during adolescence on brain neurotransmission and neurotoxicity in adult rats

PURPOSE

Tryptamine hallucinogen 5-methoxy-N,N-diisopropyltryptamine (5-MeO-DIPT) is a serotonin transporter inhibitor with high affinity for serotonin 5-HT1A and 5-HT2A/C receptors. We showed previously that 5-MeO-DIPT in a single dose increased neurotransmitter release in brain regions of rats and elicited single- and double-strand DNA breaks. Herein we investigated the effects of repeated-intermittent 5-MeO-DIPT administration in adolescence on dopamine (DA), serotonin (5-HT) and glutamate release in brain regions of adult rats. Furthermore, we examined caspase-3 activity, oxidative DNA damage, the Gpx3, Sod1, Ht1a and Ht2a mRNA expression levels, and cell viability.

METHODS

Neurotransmitter release was measured by microdialysis in freely moving animals. Caspase-3 activity was assessed colorimetrically, and oxidative DNA damage with the comet assay, while the Gpx3, Sod1, Ht1a and Ht2a mRNA expression levels were assessed by real-time polymerase chain reaction. Cell viability was studied in SH-SY5Y and Hep G2 cells by the MTT test.

RESULTS

We observed changed responses of DA, 5-HT and glutamate neurons to a challenge dose of 5-MeO-DIPT when animals were treated repeatedly in adolescence with this hallucinogen. The basal extracellular levels of DA and 5-HT were decreased in the striatum and nucleus accumbens, while glutamate level was increased in the nucleus accumbens and frontal cortex. The damage of cortical DNA, increased Gpx3 and Sod1 mRNA expression and affected caspase-3 activity were also observed. Furthermore, decreased Ht1a and Ht2a mRNA expression in the frontal cortex and marked cytotoxicity of 5-MeO-DIPT were found.

CONCLUSIONS

These results suggest that 5-MeO-DIPT given repeatedly during adolescence affects brain neurotransmission and shows neurotoxic potential observed in adult animals.

Study of the in vitro and in vivo metabolism of the tryptamine 5-MeO-MiPT using human liver microsomes and real case samples

The synthetic tryptamine 5-methoxy-N-methyl-N-isopropyltryptamine (5-MeO-MiPT) has recently been abused as a hallucinogenic drug in Germany and Switzerland. This study presents a case of 5-MeO-MiPT intoxication and the structural elucidation of metabolites in pooled human liver microsomes (pHLM), blood, and urine. Microsomal incubation experiments were performed using pHLM to detect and identify in vitro metabolites. In August 2016, the police encountered a naked man, agitated and with aggressive behavior on the street. Blood and urine samples were taken at the hospital and his premises were searched. The obtained blood and urine samples were analyzed for in vivo metabolites of 5-MeO-MiPT using liquid chromatography-high resolution tandem mass spectrometry (LC-HRMS/MS). The confiscated pills and powder samples were qualitatively analyzed using Fourier transform infrared (FTIR), gas chromatography-mass spectrometry (GC-MS), LC-HRMS/MS, and nuclear magnetic resonance (NMR). 5-MeO-MiPT was identified in 2 of the seized powder samples. General unknown screening detected cocaine, cocaethylene, methylphenidate, ritalinic acid, and 5-MeO-MiPT in urine. Seven different in vitro phase I metabolites of 5-MeO-MiPT were identified. In the forensic case samples, 4 phase I metabolites could be identified in blood and 7 in urine. The 5 most abundant metabolites were formed by demethylation and hydroxylation of the parent compound. 5-MeO-MiPT concentrations in the blood and urine sample were found to be 160 ng/mL and 3380 ng/mL, respectively. Based on the results of this study we recommend metabolites 5-methoxy-N-isopropyltryptamine (5-MeO-NiPT), 5-hydroxy-N-methyl-N-isopropyltryptamine (5-OH-MiPT), 5-methoxy-N-methyl-N-isopropyltryptamine-N-oxide (5-MeO-MiPT-N-oxide), and hydroxy-5-methoxy-N-methyl-N-isopropyltryptamine (OH-5-MeO-MiPT) as biomarkers for the development of new methods for the detection of 5-MeO-MiPT consumption, as they have been present in both blood and urine samples.

NPS: Medical Consequences Associated with Their Intake

Over the last decade, the 'traditional' drug scene has been supplemented - but not replaced - by the emergence of a range of novel psychoactive substances (NPS), which are either newly created or existing drugs, including medications, now being used in novel ways. By the end of 2014, in excess of 500 NPS had been reported by a large number of countries in the world. Most recent data show, however, that synthetic cathinones, synthetic cannabinoids, and psychedelics/phenethylamines account for the largest number of NPS.The present chapter aims at providing an overview of the clinical and pharmacological issues relating to these most popular NPS categories. Given the vast range of medical and psychopathological issues associated with the molecules here described, it is crucial for health professionals to be aware of the effects and toxicity of NPS. A general overview of the acute management of NPS adverse events is provided as well, although further studies are required to identify a range of evidence-based, index molecule-focused, treatment strategies. The rapid pace of change in the NPS online market constitutes a major challenge to the provision of current and reliable scientific knowledge on these substances.

Neurotoxic Effects of 5-MeO-DIPT: A Psychoactive Tryptamine Derivative in Rats

5-Methoxy-N,N-diisopropyltryptamine (5-MeO-DIPT, 'foxy') is one of the most popular tryptamine hallucinogens in the illicit drug market. It produces serious adverse effects, but its pharmacological profile is not well recognized. In vitro data have shown that 5-MeO-DIPT acts as a potent serotonin transporter (SERT) inhibitor and displays high affinity at serotonin 5-HT1A, 5-HT2A, and 5-HT2C receptors. In this study, using microdialysis in freely moving rats, we examined the effect of 5-MeO-DIPT on dopamine (DA), serotonin (5-HT), and glutamate release in the rat striatum, nucleus accumbens, and frontal cortex. In search of a possible neurotoxic effect of 5-MeO-DIPT, we measured DA and 5-HT tissue content in the above rat brain regions and also determined the oxidative DNA damage with the comet assay. Moreover, we tested drug-elicited head-twitch response and a forepaw treading induced by 8-OH-DPAT. 5-MeO-DIPT at doses of 5, 10, and 20 mg/kg increased extracellular DA, 5-HT, and glutamate level but the differences in the potency were found between brain regions. 5-MeO-DIPT increased 5-HT and decreased 5-HIAA tissue content which seems to result from SERT inhibition. On the other hand, a decrease in DA, DOPAC, and HVA tissue contents suggests possible adaptive changes in DA turnover or damage of DA terminals by 5-MeO-DIPT. DNA single and double-strand breaks persisted up to 60 days after the treatment, indicating marked neurotoxicity of 5-MeO-DIPT. The induction of head-twitch response and potentiation of forepaw treading induced by 8-OH-DPAT indicate that hallucinogenic activity seems to be mediated through the stimulation of 5-HT2A and 5-HT1A receptors by 5-MeO-DIPT.

Receptor interaction profiles of novel psychoactive tryptamines compared with classic hallucinogens

The present study investigated interactions between the novel psychoactive tryptamines DiPT, 4-OH-DiPT, 4-OH-MET, 5-MeO-AMT, and 5-MeO-MiPT at monoamine receptors and transporters compared with the classic hallucinogens lysergic acid diethylamide (LSD), psilocin, N,N-dimethyltryptamine (DMT), and mescaline. We investigated binding affinities at human monoamine receptors and determined functional serotonin (5-hydroxytryptamine [5-HT]) 5-HT2A and 5-HT2B receptor activation. Binding at and the inhibition of human monoamine uptake transporters and transporter-mediated monoamine release were also determined. All of the novel tryptamines interacted with 5-HT2A receptors and were partial or full 5-HT2A agonists. Binding affinity to the 5-HT2A receptor was lower for all of the tryptamines, including psilocin and DMT, compared with LSD and correlated with the reported psychoactive doses in humans. Several tryptamines, including psilocin, DMT, DiPT, 4-OH-DiPT, and 4-OH-MET, interacted with the serotonin transporter and partially the norepinephrine transporter, similar to 3,4-methylenedioxymethamphetamine but in contrast to LSD and mescaline. LSD but not the tryptamines interacted with adrenergic and dopaminergic receptors. In conclusion, the receptor interaction profiles of the tryptamines predict hallucinogenic effects that are similar to classic serotonergic hallucinogens but also MDMA-like psychoactive properties.

Neuropharmacology of New Psychoactive Substances (NPS): Focus on the Rewarding and Reinforcing Properties of Cannabimimetics and Amphetamine-Like Stimulants

New psychoactive substances (NPS) are a heterogeneous and rapidly evolving class of molecules available on the global illicit drug market (e.g smart shops, internet, “dark net”) as a substitute for controlled substances. The use of NPS, mainly consumed along with other drugs of abuse and/or alcohol, has resulted in a significantly growing number of mortality and emergency admissions for overdoses, as reported by several poison centers from all over the world. The fact that the number of NPS have more than doubled over the last 10 years, is a critical challenge to governments, the scientific community, and civil society [EMCDDA (European Drug Report), 2014; UNODC, 2014b; Trends and developments]. The chemical structure (phenethylamines, piperazines, cathinones, tryptamines, synthetic cannabinoids) of NPS and their pharmacological and clinical effects (hallucinogenic, anesthetic, dissociative, depressant) help classify them into different categories. In the recent past, 50% of newly identified NPS have been classified as synthetic cannabinoids followed by new phenethylamines (17%) (UNODC, 2014b). Besides peripheral toxicological effects, many NPS seem to have addictive properties. Behavioral, neurochemical, and electrophysiological evidence can help in detecting them. This manuscript will review existing literature about the addictive and rewarding properties of the most popular NPS classes: cannabimimetics (JWH, HU, CP series) and amphetamine-like stimulants (amphetamine, methamphetamine, methcathinone, and MDMA analogs). Moreover, the review will include recent data from our lab which links JWH-018, a CB1 and CB2 agonist more potent than Δ⁹-THC, to other cannabinoids with known abuse potential, and to other classes of abused drugs that increase dopamine signaling in the Nucleus Accumbens (NAc) shell. Thus the neurochemical mechanisms that produce the rewarding properties of JWH-018, which most likely contributes to the greater incidence of dependence associated with “Spice” use, will be described (De Luca et al., 2015a). Considering the growing evidence of a widespread use of NPS, this review will be useful to understand the new trends in the field of drug reward and drug addiction by revealing the rewarding properties of NPS, and will be helpful to gather reliable data regarding the abuse potential of these compounds.

Novel psychoactive substances of interest for psychiatry

Novel psychoactive substances include synthetic cannabinoids, cathinone derivatives, psychedelic phenethylamines, novel stimulants, synthetic opioids, tryptamine derivatives, phencyclidine-like dissociatives, piperazines, GABA-A/B receptor agonists, a range of prescribed medications, psychoactive plants/herbs, and a large series of performance and image enhancing drugs. Users are typically attracted by these substances due to their intense psychoactive effects and likely lack of detection in routine drug screenings. This paper aims at providing psychiatrists with updated knowledge of the clinical pharmacology and psychopathological consequences of the use of these substances. Indeed, these drugs act on a range of neurotransmitter pathways/receptors whose imbalance has been associated with psychopathological conditions, including dopamine, cannabinoid CB1, GABA-A/B, 5-HT2A, glutamate, and k opioid receptors. An overall approach in terms of clinical management is briefly discussed.

Recreational use, analysis and toxicity of tryptamines

The definition New psychoactive substances (NPS) refers to emerging drugs whose chemical structures are similar to other psychoactive compounds but not identical, representing a "legal" alternative to internationally controlled drugs. There are many categories of NPS, such as synthetic cannabinoids, synthetic cathinones, phenylethylamines, piperazines, ketamine derivatives and tryptamines. Tryptamines are naturally occurring compounds, which can derive from the amino acid tryptophan by several biosynthetic pathways: their structure is a combination of a benzene ring and a pyrrole ring, with the addition of a 2-carbon side chain. Tryptamines include serotonin and melatonin as well as other compounds known for their hallucinogenic properties, such as psilocybin in 'Magic mushrooms' and dimethyltryptamine (DMT) in Ayahuasca brews.

AIM

To review the scientific literature regarding tryptamines and their derivatives, providing a summary of all the available information about the structure of these compounds, their effects in relationship with the routes of administration, their pharmacology and toxicity, including articles reporting cases of death related to intake of these substances.

METHODS

A comprehensive review of the published scientific literature was performed, using also non peer-reviewed information sources, such as books, government publications and drug user web fora.

CONCLUSIONS

Information from Internet and from published scientific literature, organized in the way we proposed in this review, provides an effective tool for specialists facing the emerging NPS threat to public health and public security, including the personnel working in Emergency Department.

Interaction of psychoactive tryptamines with biogenic amine transporters and serotonin receptor subtypes

RATIONALE

Synthetic hallucinogenic tryptamines, especially those originally described by Alexander Shulgin, continue to be abused in the USA. The range of subjective experiences produced by different tryptamines suggests that multiple neurochemical mechanisms are involved in their actions, in addition to the established role of agonist activity at serotonin 2A (5-HT₂A) receptors.

OBJECTIVES

This study evaluated the interaction of a series of synthetic tryptamines with biogenic amine neurotransmitter transporters and with serotonin (5-HT) receptor subtypes implicated in psychedelic effects.

METHODS

Neurotransmitter transporter activity was determined in rat brain synaptosomes. Receptor activity was determined using calcium mobilization and DiscoveRx PathHunter assays in HEK293, Gα16-CHO, and CHOk1 cells transfected with human receptors.

RESULTS

Twenty-one tryptamines were analyzed in transporter uptake and release assays, and 5-HT₂A, serotonin 1A (5-HT₁A), and 5-HT₂A β-arrestin functional assays. Eight of the compounds were found to have 5-HT-releasing activity. Thirteen compounds were found to be 5-HT uptake inhibitors or were inactive. All tryptamines were 5-HT₂A agonists with a range of potencies and efficacies, but only a few compounds were 5-HT1A agonists. Most tryptamines recruited β-arrestin through 5-HT₂A activation.

CONCLUSIONS

All psychoactive tryptamines are 5-HT₂A agonists, but 5-HT transporter (SERT) activity may contribute significantly to the pharmacology of certain compounds. The in vitro transporter data confirm structure-activity trends for releasers and uptake inhibitors whereby releasers tend to be structurally smaller compounds. Interestingly, two tertiary amines were found to be selective substrates at SERT, which dispels the notion that 5-HT-releasing activity is limited only to primary or secondary amines.

Antiallodynic action of 1-(3-(9H-Carbazol-9-yl)-1-propyl)-4-(2-methyoxyphenyl)-4-piperidinol (NNC05-2090), a betaine/GABA transporter inhibitor

The GABAergic system in the spinal cord has been shown to participate in neuropathic pain in various animal models. GABA transporters (GATs) play a role in controlling the synaptic clearance of GABA; however, their role in neuropathic pain remains unclear. In the present study, we compared the betaine/GABA transporter (BGT-1) with other GAT subtypes to determine its participation in neuropathic pain using a mouse model of sciatic nerve ligation. 1-(3-(9H-Carbazol-9-yl)-1-propyl)-4-(2-methyoxyphenyl)-4-piperidinol (NNC05-2090), an inhibitor that displays moderate selectivity for BGT-1, had an antiallodynic action on model mice treated through both intrathecally and intravenous administration routes. On the other hand, SKF89976A, a selective GAT-1 inhibitor, had a weak antiallodynic action, and (S)-SNAP5114, an inhibitor that displays selectivity for GAT-3, had no antiallodynic action. Systemic analysis of these compounds on GABA uptake in CHO cells stably expressing BGT-1 revealed that NNC05-2090 not only inhibited BGT-1, but also serotonin, noradrenaline, and dopamine transporters, using a substrate uptake assay in CHO cells stably expressing each transporter, with IC50: 5.29, 7.91, and 4.08 μM, respectively. These values were similar to the IC50 value at BGT-1 (10.6 μM). These results suggest that the antiallodynic action of NNC05-2090 is due to the inhibition of both BGT-1 and monoamine transporters.

Recreational drug discovery: natural products as lead structures for the synthesis of smart drugs

Covering: up to December 2013. Over the past decade, there has been a growing transition in recreational drugs from natural materials (marijuana, hashish, opium), natural products (morphine, cocaine), or their simple derivatives (heroin), to synthetic agents more potent than their natural prototypes, which are sometimes less harmful in the short term, or that combine properties from different classes of recreational prototypes. These agents have been named smart drugs, and have become popular both for personal consumption and for collective intoxication at rave parties. The reasons for this transition are varied, but are mainly regulatory and commercial. New analogues of known illegal intoxicants are invisible to most forensic detection techniques, while the alleged natural status and the lack of avert acute toxicity make them appealing to a wide range of users. On the other hand, the advent of the internet has made possible the quick dispersal of information among users and the on-line purchase of these agents and/or the precursors for their synthesis. Unlike their natural products chemotypes (ephedrine, mescaline, cathinone, psilocybin, THC), most new drugs of abuse are largely unfamiliar to the organic chemistry community as well as to health care providers. To raise awareness of the growing plague of smart drugs we have surveyed, in a medicinal chemistry fashion, their development from natural products leads, their current methods of production, and the role that clandestine home laboratories and underground chemists have played in the surge of popularity of these drugs.

The recreational tryptamine 5-MeO-DALT (N,N-diallyl-5-methoxytryptamine): a brief review

5-MeO-DALT (N,N-diallyl-5-methoxytryptamine) is a psychoactive substance, sold primarily over the Internet as a 'research chemical' or 'plant food'. Although details for the synthesis of this tryptamine have been available since 2004, its use as a hallucinogenic drug has been reported only occasionally in on-line user fora. It is controlled in only a few countries world-wide. There is little scientifically-based literature on the pharmacological, physiological, psychopharmacological, toxicological and epidemiological characteristics of 5-MeO-DALT. Here we review what is known about these aspects. We also report what we believe to be the first death involving the use of this substance. The case involved a man in his mid-20s who died in mid-2010. The coroner concluded that the deceased "died from injuries sustained after being hit by a lorry whilst under the influence of 5-MeODALT". It is critical that any other cases, including non-fatal instances, are documented so that a scientific evidence-base can be established for this drug.

Cardiovascular toxicity of novel psychoactive drugs: lessons from the past

The long use of ephedrine, amphetamines, cocaine, LSD and more recently 3,4-methylenedioxy-N-methylamphetamine (MDMA; "Ecstasy") allows us to predict with some confidence what cardiovascular risks are likely to be associated with novel psychoactive substances (NPS). Once the probably multiple biological activities of a compound are known it is possible to define the likely risks of cardiovascular toxicity. Agonists of 5-HT(2A) receptors or alpha-adrenoceptors may cause vasoconstriction and tissue ischemia. Drugs which have agonist affinity for 5-HT(2B) receptors will probably promote heart valve fibrosis leading to heart failure. Compounds that interfere with uptake of dopamine or 5-hydroxytryptamine (5-HT) are likely to also have effects on noradrenergic neurotransmission and lead to sympathomimetic effects on the heart and vasculature. Drugs that cause dopamine release, or inhibit uptake are likely to be addictive and lead to chronic use. Other drugs (particularly the so-called empathogens) are associated with weekly usage in social settings; over time such use can lead to cardiovascular harm. Defining which of these effects NPS have is an important element of predicting the harm they may cause and informing those appointed to introduce regulations to control them.

MAGE-D1 regulates expression of depression-like behavior through serotonin transporter ubiquitylation

The ubiquitin-proteasome system (UPS) controls the stability of most cellular proteins. The polymorphism of UPS-related genes is associated with major depression disorder, but less is known about the molecule that plays a role in depression by modulating the UPS. Melanoma antigen gene-D1 (MAGE-D1) interacts with RING E3 ubiquitin ligase and is implicated in protein degradation. MAGE-D1 may thus play an important role in the CNS via ubiquitylation. Here, we clarified a novel role of MAGE-D1 in emotional functions, namely its modulation of ubiquitylation to the serotonin transporter (SERT). The MAGE-D1 knock-out and knockdown by small interfering RNA (siRNA) in the prefrontal cortex showed depression-like behavior, such as a decrease in exploratory behavior in both the home cage and novel apparatus, a decrease in social interaction, increased immobility time during forced swimming and tail suspension, and a decrease in sucrose preference without any anxiety, or cognitive or motor dysfunction. Acute and chronic (28 d) administration of sertraline (10 mg/kg) and imipramine (20 mg/kg) reversed all or part of depression-like behavior in knock-out mice. In these mice, the serotonergic function in the prefrontal cortex and hippocampus was hypoactive, accompanied by hyperexpression of SERT attributable to a decrease in ubiquitylation. Furthermore, MAGE-D1 binds to SERT via the necdin homology domain. MAGE-D1 overexpression in cells resulted in a decrease in serotonin uptake activity and the protein level of SERT but an increase in ubiquitylated SERT. Together, the present findings suggest a novel role for MAGE-D1 in depressive behaviors: modulating SERT ubiquitylation.

Inhibitory action of antidepressants on mouse Betaine/GABA transporter (BGT1) heterologously expressed in cell cultures

Betaine/γ-aminobutyric acid (GABA) transporter (BGT1, SLC6A12) is a member of the Na⁺- and Cl⁻-dependent neurotransmitter transporter gene family with a homology to the GABA transporters (GATs), GAT1 (SLC6A1), GAT2 (SLC6A13) and GAT3 (SLC6A11) (HUGO nomenclature). Since antidepressants have been reported to inhibit GABA uptake, we examined those effects on mouse BGT1 (mBGT1) in comparison with other mouse GAT (mGAT) subtypes in the heterologously expressed cell cultures. All antidepressants tested here inhibited the [³H]GABA uptake through mBGT1 and mGATs in a rank order of potency with mBGT1 > mGAT1-3. Kinetic analyses for maprotilline, mianserine and trimipramine revealed that they inhibited mBGT1 and mGAT1 noncompetitively, except that mianserine competitively inhibited mBGT1. These results provided a clue to investigate the structure-function relationship of mBGT1 using antidepressants as a tool, leading to the identification of potential candidates for selective and specific inhibitors of mBGT1.

Electroencephalographic and convulsive effects of binge doses of (+)-methamphetamine, 5-methoxydiisopropyltryptamine, and (±)-3,4-methylenedioxymethamphetamine in rats

The abuse of drugs such as methamphetamine (MA), 3,4-methylenedioxymethamphetamine (Ecstasy, MDMA), and 5-methoxydiisopropyltryptamine (5-MeO-DIPT; Foxy) is global. Symptoms from taking these drugs include tachycardia, agitation, hyperpyrexia, and sometimes seizures. We compared the EEG effects of these drugs in male Sprague-Dawley rats (~300 g) implanted with cortical electroencephalographic (EEG) electrodes prior to testing. Animals received four subcutaneous injections of MA, MDMA, or Foxy (10 mg/kg each as freebase, administered every 2 h), or saline as these doses produce lasting effects on learning, memory, and monoamines. EEG tracings were recorded before, during, and after treatment. Animals receiving MDMA showed no significant EEG abnormalities or myoclonus. MA treatment resulted in myoclonic activity and in brief (<10 s) EEG epileptiform activity in ~50% of the rats. Longer seizure activity (10 s to 5 min) was recorded in some MA-treated rats following the third and fourth doses. The onset of myoclonic activity following Foxy treatment occurred shortly after the first dose. All rats receiving Foxy showed seizures by the second dose and this continued throughout the treatment regimen. The results show that binge doses of MA and MDMA, which mimic the neurochemical changes seen in chronic users, increase EEG abnormalities after MA but not after MDMA. While the neurochemical effects of Foxy are not known in humans, this drug causes severe EEG abnormalities and overt seizures in 100% of tested animals.

Methylone and monoamine transporters: correlation with toxicity

Methylone (2-methylamino-1-[3,4-methylenedioxyphenyl]propane-1-one) is a synthetic hallucinogenic amphetamine analog, like MDMA (3,4-methylenedioxy- methamphetamine), considered to act on monoaminergic systems. However, the psychopharmacological profile of its cytotoxicity as a consequence of monoaminergic deficits remains unclear. We examined here the effects of methylone on the transporters for dopamine (DAT), norepinephrine (NET), and serotonin (SERT), using a heterologous expression system in CHO cells, in association with its cytotoxicity. Methylone inhibited the activities of DAT, NET, and SERT, but not GABA transporter-1 (GAT1), in a concentration-dependent fashion with a rank order of NET > DAT > SERT. Methylone was less effective at inhibiting DAT and NET, but more effective against SERT, than was methamphetamine. Methylone alone was not toxic to cells except at high concentrations, but in combination with methamphetamine had a synergistic effect in CHO cells expressing the monoamine transporters but not in control CHO cells or cells expressing GAT1. The ability of methylone to inhibit monoamine transporter function, probably by acting as a transportable substrate, underlies the synergistic effect of methylone and methamphetamine.

Multiple receptors contribute to the behavioral effects of indoleamine hallucinogens

Serotonergic hallucinogens produce profound changes in perception, mood, and cognition. These drugs include phenylalkylamines such as mescaline and 2,5-dimethoxy-4-methylamphetamine (DOM), and indoleamines such as (+)-lysergic acid diethylamide (LSD) and psilocybin. Despite their differences in chemical structure, the two classes of hallucinogens produce remarkably similar subjective effects in humans, and induce cross-tolerance. The phenylalkylamine hallucinogens are selective 5-HT(2) receptor agonists, whereas the indoleamines are relatively non-selective for serotonin (5-HT) receptors. There is extensive evidence, from both animal and human studies, that the characteristic effects of hallucinogens are mediated by interactions with the 5-HT(2A) receptor. Nevertheless, there is also evidence that interactions with other receptor sites contribute to the psychopharmacological and behavioral effects of the indoleamine hallucinogens. This article reviews the evidence demonstrating that the effects of indoleamine hallucinogens in a variety of animal behavioral paradigms are mediated by both 5-HT(2) and non-5-HT(2) receptors.

Glucose and corticosterone changes in developing and adult rats following exposure to (+/-)-3,4-methylendioxymethamphetamine or 5-methoxydiisopropyltryptamine

The use of the club drugs 3,4-methylenedioxymethamphetamine (MDMA) and 5-methoxy-n,n-diisopropyltryptamine (Foxy) is of growing concern, especially as many of the effects, particularly during development, are unknown. The effects of these drugs upon homeostasis may be important since both are known to stimulate the hypothalamic-pituitary-adrenal axis. The purpose of this experiment was to examine alterations in rats in corticosterone and glucose following an acute exposure to these drugs at different stages of development: preweaning, juvenile, and adulthood. Both MDMA and Foxy increased corticosterone levels significantly at all ages examined, while glucose was elevated at all stages except at the juvenile time point (postnatal day 28). For both measures, there were no differences between the sexes with either drug. The data indicate that an acute exposure to these drugs alters CORT and glucose levels, raising the possibility that these changes may have effects on behavioral and cognitive function, as we and others have previously demonstrated.

Neuropsychotoxicity of abused drugs: molecular and neural mechanisms of neuropsychotoxicity induced by methamphetamine, 3,4-methylenedioxymethamphetamine (ecstasy), and 5-methoxy-N,N-diisopropyltryptamine (foxy)

Psychostimulants including amphetamines and cocaine, opioids including morphine, and some recreational drugs share the ability to cause drug dependence and addiction. Although these drugs of abuse primarily act on distinct molecular targets, such as monoamine transporters or receptors, they finally converge to common neural pathways. Several lines of evidence suggest that their chronic treatment leads to the enhancement of the mesocorticolimbic dopaminergic neurons from the ventral tegmental area (VTA) to the nucleus accumbens (NAc) and the medial prefrontal cortex (mPFC) and leads to abnormal glutamatergic function from the mPFC to the NAc and VTA. The neural adaptation of dopaminergic-glutamatergic system is considered to be critically implicated in neuropsychotoxic effects of these drugs of abuse. In addition, recent studies suggest that the serotonergic neurons from the raphe nuclei to limbic areas modulate the mesocorticolimbic dopaminergic-glutamatergic system and participate in the neuropsychotoxicity. In this review, our recent in vitro studies on the molecular targets and neural adaptation of methamphetamine, 3,4-methylenedioxymethamphetamine (MDMA, "ecstasy"), and 5-methoxy-N,N-diisopropyltryptamine (5-MeO-DiPT, "foxy") using Xenopus oocytes, organotypic slice cultures of the mesocorticolimbic dopaminergic-glutamatergic system, and the raphe serotonergic system are introduced.