Biological and Pharmaceutical Bulletin
January 1, 1995
Yuji Nakahara, Kazunori Takahashi, Ruri Kikura
200 citations
The incorporation rate of drugs into hair is strongly correlated with melanin affinity and, to a lesser extent, lipophilicity. Among 20 tested drugs, cocaine had the highest incorporation rate, while THCA had the lowest—a 3600-fold difference. Melanin affinity alone correlated with incorporation rate at r = 0.947; combining melanin affinity and lipophilicity raised the correlation to 0.979. Basic drugs showed higher incorporation rates than neutral or acidic ones, likely due to membrane permeability driven by the pH gradient between blood (pH 7.4) and the acidic hair matrix.
Biological and Pharmaceutical Bulletin
October 23, 2014
Yuichi Sakashita, Kenji Abe, N. Katagiri et al.
84 citations
Psilocin, the active metabolite of psilocybin, increases extracellular dopamine in the nucleus accumbens but not in the ventral tegmental area (VTA) of awake rats. It also raises serotonin (5-HT) levels in the medial prefrontal cortex while decreasing dopamine there. Neither dopamine nor 5-HT levels change in the VTA. Behaviorally, psilocin increases the number of head twitches. The findings suggest psilocin affects the dopaminergic system in the nucleus accumbens and the serotonergic system in the medial prefrontal cortex, acting through the mesoaccumbens and mesocortical pathways.
Biological and Pharmaceutical Bulletin
January 1, 2007
Ryouichi Nonaka, Fumiko Nagai, Akio Ogata et al.
31 citations
A new small-scale method measures how psychoactive drugs activate monoamine receptors by tracking G protein binding in rat brain membranes. The method simultaneously tests dopamine, serotonin, and norepinephrine effects. Among 12 phenethylamines tested, only 2C-C, 2C-E, and 2C-I stimulated G protein binding; the rest had no effect. All 7 tryptamines tested stimulated binding, with 5-MeO-DMT being most potent, followed by 5-MeO-DALT, 5-MeO-AMT, 5-MeO-MIPT, 5-MeO-DIPT, DPT, and AMT. The assay can help classify psychoactive substances as prohibited under Tokyo Metropolitan criteria.
Biological and Pharmaceutical Bulletin
January 1, 1997
Yuji Nakahara, Ruri Kikura
18 citations
In rats given acute poisonous doses of MDMA (20–100 mg/kg), the drug appeared in hair roots within minutes and reached high concentrations (up to 156 ng/mg). In surviving animals, MDMA levels in hair roots rose for up to 6 hours and then slowly declined over 24 hours. Washing removed more drug early on, indicating that MDMA is not immediately immobilized in hair roots but gradually becomes incorporated into the hair shaft. After death, MDMA concentrations stopped increasing, and the ratio of its metabolite MDA to MDMA plateaued, reflecting halted hair growth and metabolism. MDMA was incorporated into and retained in hair more quickly and firmly than methamphetamine.
Biological and Pharmaceutical Bulletin
January 1, 1995
Kenji Watanabe, Yuichiro Kayano, Tatsuo Matsunaga et al.
9 citations
An intermediate metabolite of mescaline, 3,4,5-trimethoxyphenylacetaldehyde, is oxidized to 3,4,5-trimethoxyphenylacetic acid by mouse liver microsomes. The reaction requires NADPH and is inhibited by SKF 525-A, metyrapone, and disulfiram. A specific P450 isozyme, CYP2C29, catalyzes the reaction at a rate of 0.96 nmol/min/nmol P450, with NADPH and NADPH-cytochrome c reductase essential. Oxygen incorporation was confirmed using oxygen-18 gas and GC-MS analysis. Antibody against CYP2C29 inhibited activity by 35%, indicating this isozyme plays a major role. Pharmacological tests in mice showed that mescaline's deaminated metabolites are much less active or inactive in cataleptogenic effect and pentobarbital-induced sleep prolongation compared to mescaline itself.