3rd February 2018 at 4:39 pm #900
Aminoindanes, piperazines, and pipradrol derivatives are novel psychoactive substances found in “Ecstasy” tablets as replacements for 3,4-methylenedioxymethamphetamine (MDMA) or substances sold as “ivory wave.” The pharmacology of these MDMA- and methylphenidate-like substances is poorly known. We characterized the pharmacology of the aminoindanes 5,6-methylenedioxy-2-aminoindane (MDAI), 5-iodoaminoindane (5-IAI), and 2-aminoindane (2-AI), the piperazines meta-chlorophenylpiperazine (m-CPP), trifluoromethylphenylpiperazine (TFMPP), and 1-benzylpiperazine (BZP), and the pipradrol derivatives desoxypipradrol (2-diphenylmethylpiperidine [2-DPMP]), diphenylprolinol (diphenyl-2-pyrrolidinemethanol [D2PM]), and methylphenidate. We investigated norepinephrine (NE), dopamine (DA), and serotonin (5-hydroxytryptamine [5-HT]) uptake inhibition using human embryonic kidney 293 (HEK 293) cells that express the respective human monoamine transporters (NET, DAT, and SERT). We also evaluated the drug-induced efflux of NE, DA, and 5-HT from monoamine-preloaded cells and the binding affinity to monoamine transporters and receptors, including trace amine-associated receptor 1 (TAAR1). 5-IAI and MDAI preferentially inhibited the SERT and NET and released 5-HT. 2-AI interacted with the NET. BZP blocked the NET and released DA. m-CPP and TFMPP interacted with the SERT and serotonergic receptors. The pipradrol derivatives were potent and selective catecholamine transporter blockers without substrate releasing properties. BZP, D2PM, and 2-DPMP lacked serotonergic activity and TAAR1 binding, in contrast to the aminoindanes and phenylpiperazines. In summary, all of the substances were monoamine transporter inhibitors, but marked differences were found in their DAT vs. SERT inhibition profiles, release properties, and receptor interactions. The pharmacological profiles of D2PM and 2-DPMP likely predict a high abuse liability.
Graphical abstract27th March 2018 at 4:28 pm #5636
The mechanism of 3,4-methylenedioxymethamphetamine (d-MDMA)-induced neurotoxicity may involve formation of toxic radical species. Endogenous defenses against toxic radical species include tissue stores of vitamin E, and thiols. We examined whether vitamin E deficiency could alter d-MDMA-induced neurotoxicity by administration of the drug to animals with diet induced vitamin E deficiency. Brain vitamin E levels in deficient mice were reduced 75% compared to sufficient animals. Animals received d-MDMA 5 or 10 mg/kg or saline (delivered every 2 h×4, s.c.). Diet slightly altered d-MDMA-induced temperature modulation. In brain, MDMA treatment reduced vitamin E, total antioxidant reserve and protein thiols 72 h after the first dose. In liver, MDMA treatment reduced glutathione and total antioxidant reserve at the same time point. The vitamin E-deficient group, treated with the low dose of d-MDMA, exhibited neurotoxic responses, including reduced striatal dopamine (47%) and elevated GFAP protein (3-fold): while the sufficient diet group was not altered. The higher d-MDMA dose caused neurotoxic responses in both diet groups. Liver toxicity was determined by histopathologic examination. d-MDMA caused hepatic necrosis that was more severe in vitamin E deficient than sufficient mice. These data indicate that (1) d-MDMA administration reduces antioxidant measures at a time coincident with d-MDMA-induced neuronal damage and (2) vitamin E deficiency increases susceptibility to d-MDMA-induced neurotoxicity and hepatic necrosis.
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