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.

In recent years, lipids have come to the foreground as signaling mediators in the central nervous system (CNS) 1,2 . While classical neurotransmitters are stored in synaptic vesicles and released on fusion with the plasma membrane of neurons, due to their lipophilic nature, lipids readily diffuse through membranes and are not stored in vesicles. It is, therefore, generally accepted that signaling lipids are produced 'on demand' and are rapidly metabolized to terminate their biological action 3 . In particular, NAEs, including N-palmitoylethanolamine (PEA), N-oleoylethanolamine (OEA) and the endocannabinoid anandamide (N-arachidonoylethanolamine, AEA) have emerged as key lipid signaling molecules. Genetic deletion or pharmacological inhibition of the main NAE hydrolytic enzyme, fatty acid amide hydrolase (FAAH), revealed elevated anandamide, PEA and OEA levels in brain and implicated these molecules in the modulation of various physiological processes such as pain, stress, anxiety, appetite, cardiovascular function and inflammation [4][5][6][7] . The physiological effects resulting from perturbation of the production of anandamide and other NAEs in living systems are, however, poorly studied, partly because of a lack of pharmacological tools to modulate their biosynthetic enzymes 8 . NAPE-PLD is generally considered a principal NAE biosynthetic enzyme 9,10 . Biochemical and structural studies have demonstrated that NAPE-PLD is a membrane-associated, constitutively active zinc hydrolase with a metallo-β-lactamase fold 11 . The enzyme generates a broad range of NAEs by hydrolysis of the phosphodiester bond between the phosphoglyceride and the NAE in N-acylphosphatidylethanolamines (NAPEs) 12 . Knockout (KO) studies have shown that the Ca 2+ -dependent conversion of NAPE to NAEs bearing both saturated and polyunsaturated fatty acyl groups are fivefold reduced in brain lysates from mice that genetically lack Napepld 13 . In accordance, reduced levels of saturated and mono-unsaturated NAEs were observed in the brains of NAPE-PLD KO mice [13][14][15] . Anandamide levels were not reduced in the transgenic model reported by Leung et al., which suggested the presence of compensatory mechanisms 13 . Indeed, multiple alternative biosynthetic pathways for anandamide have been discovered since 10 .

In order to investigate the in vivo dopamine (DA) stimulant properties of selected 3rd generation Spice/K2 cannabinoids, BB-22, 5F-PB-22, 5F-AKB-48 and STS-135, their in vitro affinity and agonist potency at native rat and mice CB1 receptors was studied. The compounds bind with high affinity to CB1 receptors in rat cerebral cortex homogenates and stimulate CB1-induced [(35)S]GTPγS binding with high potency and efficacy. BB-22 and 5F-PB-22 showed the lowest Ki of binding to CB1 receptors (0.11 and 0.13 nM), i.e., 30 and 26 times lower respectively than that of JWH-018 (3.38 nM), and a potency (EC50, 2.9 and 3.7 nM, respectively) and efficacy (Emax, 217% and 203%, respectively) as CB1 agonists higher than JWH-018 (EC50, 20.2 nM; Emax, 163%). 5F-AKB-48 and STS-135 had higher Ki for CB1 binding, higher EC50 and lower Emax as CB1 agonists than BB-22 and 5F-PB-22 but still comparatively more favourable than JWH-018. The agonist properties of all the compounds were abolished or drastically reduced by the CB1 antagonist/inverse agonist AM251 (0.1 μM). No activation of G-protein was observed in CB1-KO mice. BB-22 (0.003-0.01 mg/kg i.v.) increased dialysate DA in the accumbens shell but not in the core or in the medial prefrontal cortex, with a bell shaped dose-response curve and an effect at 0.01 mg/kg and a biphasic time-course. Systemic AM251 (1.0 mg/kg i.p.) completely prevented the stimulant effect of BB-22 on dialysate DA in the NAc shell. All the other compounds increased dialysate DA in the NAc shell at doses consistent with their in vitro affinity for CB1 receptors (5F-PB-22, 0.01 mg/kg; 5F-AKB-48, 0.1 mg/kg; STS-135, 0.15 mg/kg i.v.). 3rd generation cannabinoids can be even more potent and super-high CB1 receptor agonists compared to JWH-018. Future research will try to establish if these properties can explain the high toxicity and lethality associated with these compounds.

4-Iodo-2,5-dimethoxy-N-(2-methoxybenzyl)phenethylamine (25I-NBOMe), commonly called "N-Bomb," is a synthetic phenethylamine with psychedelic and entactogenic effects; it was available on the Internet both as a legal alternative to lysergic acid diethylamide (LSD) and as a surrogate of 3,4-methylenedioxy-methamphetamine (MDMA), but now it has been scheduled among controlled substances. 25I-NBOMe acts as full agonist on serotonergic 5-HT2A receptors. Users are often unaware of ingesting fake LSD, and several cases of intoxication and fatalities have been reported. In humans, overdoses of "N-Bomb" can cause tachycardia, hypertension, seizures, and agitation. Preclinical studies have not yet widely investigated the rewarding properties and behavioral effects of this compound in both sexes. Therefore, by in vivo microdialysis, we evaluated the effects of 25I-NBOMe on dopaminergic (DA) and serotonergic (5-HT) transmissions in the nucleus accumbens (NAc) shell and core, and the medial prefrontal cortex (mPFC) of male and female rats. Moreover, we investigated the effect of 25I-NBOMe on sensorimotor modifications as well as body temperature, nociception, and startle/prepulse inhibition (PPI). We showed that administration of 25I-NBOMe affects DA transmission in the NAc shell in both sexes, although showing different patterns; moreover, this compound causes impaired visual responses in both sexes, whereas core temperature is heavily affected in females, and the highest dose tested exerts an analgesic effect prominent in male rats. Indeed, this drug is able to impair the startle amplitude with the same extent in both sexes and inhibits the PPI in male and female rats. Our study fills the gap of knowledge on the behavioral effects of 25I-NBOMe and the risks associated with its ingestion; it focuses the attention on sex differences that might be useful to understand the trend of consumption as well as to recognize and treat intoxication and overdose symptoms.Neuropharmacology of the Synthetic Hallucinogen 25I-NBOMe Miliano et al.

In the last decade, the trend of drug consumption has completely changed, and several new psychoactive substances (NPS) have appeared on the drug market as legal alternatives to common drugs of abuse. Designed to reproduce the effects of illegal substances like cannabis, ecstasy, cocaine, or ketamine, NPS are only in part controlled by UN conventions and represent an emerging threat to global public health. The effects of NPS greatly differ from drug to drug and relatively scarce information is available at present about their pharmacology and potential toxic effects. Yet, compared to more traditional drugs, more dangerous short- and long-term effects have been associated with their use, and hospitalizations and fatal intoxications have also been reported after NPS use. In the era of cyberculture, the Internet acts as an ideal platform to promote and market these compounds, leading to a global phenomenon. Hidden by several aliases, these substances are sold across the web, and information about consumption is shared by online communities through drug fora, YouTube channels, social networks, and smartphone applications (apps). This review intends to provide an overview and analysis of social media that contribute to the popularity of NPS especially among young people. The possibility of using the same channels responsible for their growing diffusion to make users aware of the risks associated with NPS use is proposed.