Andrea Ossato

Effect of the novel synthetic cannabinoids AKB48 and 5F-AKB48 on “tetrad”, sensorimotor, neurological and neurochemical responses in mice. In vitro and in vivo pharmacological studies

RationaleAKB48 and its fluorinate derivate 5F-AKB48 are two novel synthetic cannabinoids belonging to a structural class with an indazole core structure. They are marketed as incense, herbal preparations or chemical supply for their psychoactive Cannabis-like effects.ObjectivesThe present study was aimed at investigating the in vitro and in vivo pharmacological activity of AKB48 and 5F-AKB48 in male CD-1 mice and comparing their in vivo effects with those caused by the administration of Δ9-THC and JWH-018.ResultsIn vitro competition binding experiments performed on mouse and human CB1 and CB2 receptors revealed a nanomolar affinity and potency of the AKB48 and 5F-AKB48. In vivo studies showed that AKB48 and 5F-AKB48, induced hypothermia, increased pain threshold to both noxious mechanical and thermal stimuli, caused catalepsy, reduced motor activity, impaired sensorimotor responses (visual, acoustic and tactile), caused seizures, myoclonia, hyperreflexia and promoted aggressiveness in mice. Moreover, microdialysis study in freely moving mice showed that systemic administration of AKB48 and 5F-AKB48 stimulated dopamine release in the nucleus accumbens. Behavioural, neurological and neurochemical effects were fully prevented by the selective CB1 receptor antagonist/inverse agonist AM 251.ConclusionsFor the first time, the present study demonstrates the overall pharmacological effects induced by the administration of AKB48 and 5F-AKB48 in mice and suggests that the fluorination can increase the power and/or effectiveness of SCBs. Furthermore, this study outlines the potential detrimental effects of SCBs on human health.

Psychostimulant Effect of the Synthetic Cannabinoid JWH-018 and AKB48: Behavioral, Neurochemical, and Dopamine Transporter Scan Imaging Studies in Mice

JWH-018 and AKB48 are two synthetic cannabinoids (SCBs) belonging to different structural classes and illegally marketed as incense, herbal preparations, or chemical supply for theirs psychoactive cannabis-like effects. Clinical reports from emergency room reported psychomotor agitation as one of the most frequent effects in people assuming SCBs. This study aimed to investigate the psychostimulant properties of JWH-018 and AKB48 in male CD-1 mice and to compare their behavioral and biochemical effects with those caused by cocaine and amphetamine. In vivo studies showed that JWH-018 and AKB48, as cocaine and amphetamine, facilitated spontaneous locomotion in mice. These effects were prevented by CB1 receptor blockade and dopamine (DA) D1/5 and D2/3 receptors inhibition. SPECT-CT studies on dopamine transporter (DAT) revealed that, as cocaine and amphetamine, JWH-018 and AKB48 decreased the [123I]-FP-CIT binding in the mouse striatum. Conversely, in vitro competition binding studies revealed that, unlike cocaine and amphetamine, JWH-018 and AKB48 did not bind to mouse or human DAT. Moreover, microdialysis studies showed that the systemic administration of JWH-018, AKB48, cocaine, and amphetamine stimulated DA release in the nucleus accumbens (NAc) shell of freely moving mice. Finally, unlike amphetamine and cocaine, JWH-018 and AKB48 did not induce any changes on spontaneous [3H]-DA efflux from murine striatal synaptosomes. The present results suggest that SCBs facilitate striatal DA release possibly with different mechanisms than cocaine and amphetamine. Furthermore, they demonstrate, for the first time, that JWH-018 and AKB48 induce a psychostimulant effect in mice possibly by increasing NAc DA release. These data, according to clinical reports, outline the potential psychostimulant action of SCBs highlighting their possible danger to human health.

Pharmaco‐toxicological effects of the novel third‐generation fluorinate synthetic cannabinoids, 5F‐ADBINACA, AB‐FUBINACA, and STS‐135 in mice. In vitro and in vivo studies

5F‐ADBINACA, AB‐FUBINACA, and STS‐135 are 3 novel third‐generation fluorinate synthetic cannabinoids that are illegally marketed as incense, herbal preparations, or research chemicals for their psychoactive cannabis‐like effects.

The Cathinones MDPV and α-PVP Elicit Different Behavioral and Molecular Effects Following Acute Exposure

Since the mid-to-late 2000s, synthetic cathinones have gained popularity among drug users due to their psychostimulant effects greater than those produced by cocaine and amphetamine. Among them, 3,4-methylenedioxypyrovalerone (MDPV) and 1-phenyl-2-(pyrrolidin-1-yl)pentan-1-one (α-PVP) are ones of the most popular cathinones available in the clandestine market as “bath salts” or “fertilizers.” Pre-clinical studies indicate that MDPV and α-PVP induced psychomotor stimulation, affected thermoregulation, and promoted reinforcing properties in rodents. However, a direct comparative analysis on the effects caused by MDPV and α-PVP on the behavior and neuronal activation in rodents is still lacking. Behavioral analyses revealed that both MDPV and α-PVP affect spontaneous and stimulated motor responses. In particular, MDPV showed a greater psychomotor effect than α-PVP in line with its higher potency in blocking the dopamine transporter (DAT). Notably, MDPV was found to be more effective than α-PVP in facilitating spontaneous locomotion and it displayed a biphasic effect in contrast to the monophasically stimulated locomotion induced by α-PVP. In addition to the behavioral results, we also found a different modulation of immediate early genes (IEGs) such as Arc/Arg3.1 and c-Fos in the frontal lobe, striatum, and hippocampus, indicating that these drugs do impact brain homeostasis with changes in neuronal activity that depend on the drug, the brain area analyzed, and the timing after the injection. These results provide the first discrimination between MDPV and α-PVP based on behavioral and molecular data that may contribute to explain, at least in part, their toxicity.

Neurological, sensorimotor and cardiorespiratory alterations induced by methoxetamine, ketamine and phencyclidine in mice

ABSTRACT Novel psychoactive substances are intoxicating compounds developed to mimic the effects of well‐established drugs of abuse. They are not controlled by the United Nations drug convention and pose serious health concerns worldwide. Among them, the dissociative drug methoxetamine (MXE) is structurally similar to ketamine (KET) and phencyclidine (PCP) and was created to purposely mimic the psychotropic effects of its “parent” compounds. Recent animal studies show that MXE is able to stimulate the mesolimbic dopaminergic transmission and to induce KET‐like discriminative and rewarding effects. In light of the renewed interest in KET and PCP analogs, we decided to deepen the investigation of MXE‐induced effects by a battery of behavioral tests widely used in studies of “safety‐pharmacology” for the preclinical characterization of new molecules. To this purpose, the acute effects of MXE on neurological and sensorimotor functions in mice, including visual, acoustic and tactile responses, thermal and mechanical pain, motor activity and acoustic startle reactivity were evaluated in comparisons with KET and PCP to better appreciate its specificity of action. Cardiorespiratory parameters and blood pressure were also monitored in awake and freely moving animals. Acute systemic administrations of MXE, KET and PCP (0.01–30 mg/kg i.p.) differentially alter neurological and sensorimotor functions in mice depending in a dose‐dependent manner specific for each parameter examined. MXE and KET (1 and 30 mg/kg i.p.) and PCP (1 and 10 mg/kg i.p.) also affect significantly cardiorespiratory parameters, systolic and diastolic blood pressure in mice. HighlightsMethoxetamine (MXE) is a ketamine (KET) ‐ like novel psychoactive substance (NPS).Number of MXE‐induced acute toxicity are increasing at an alarming rate.MXE induces significant neurological, sensorimotor, cardiorespiratory alterations.MXE effects were qualitatively but not quantitatively similar to KET and phencyclidine.

Phenotypic effects of chronic and acute use of methiopropamine in a mouse model

Methiopropamine (MPA) is a structural analogue of methamphetamine and belongs to the category of the novel psychoactive substances. To the best of our knowledge, no experimental study has been performed to evaluate the organ damage evoked by MPA administration in an animal model. Therefore, the main purpose of the present study was to investigate the histological changes in CD-1 male mice following the chronic administration of MPA. MPA-chronically treated mice showed myocardial damage with features consistent with repeated episodes of ischemia and a pattern of kidney damage and gastrointestinal ischemia, with ischemic-necrotic lesions of variable extent. In agreement with the analogies between MPA and methamphetamine, we link organ damage secondary to MPA administration to the vasoconstrictive effect exhibited by both compounds. Chronically MPA-treated mice did not show changes in body weight, food intake, thermoregulation, muscular strength and motor coordination in the accelerod test. However, acute MPA administration significantly increased their heart rate and promoted vasoconstriction, which were associated with the sudden death of a subset of animals (40% of all chronically treated mice). In conclusion, the present study demonstrates that MPA consumption could induce health hazards, highlighting the risk of sudden catastrophic events; therefore, clinicians should be aware of these data and consider MPA screening when no other drug is identified by a urine drug screen.

1-cyclohexyl-x-methoxybenzene derivatives, novel psychoactive substances seized on the internet market. Synthesis and in vivo pharmacological studies in mice

Among novel psychoactive substances notified to EMCDDA and Europol were 1‐cyclohexyl‐x‐methoxybenzene stereoisomers (ortho, meta, and para). These substances share some structural characteristics with phencyclidine and tramadol. Nowadays, no information on the pharmacological and toxicological effects evoked by 1‐cyclohexyl‐x‐methoxybenzene are reported. The aim of this study was to investigate the effect evoked by each one stereoisomer on visual stimulation, body temperature, acute thermal pain, and motor activity in mice.