5-hydroxytryptamine- and dopamine-releasing effects of ring-substituted amphetamines on rat brain: a comparative study using in vivo microdialysis.

Using in vivo microdialysis, a comparative study was conducted to examine the effects of amphetamine-related compounds (methamphetamine, MAP; 3,4-methylenedioxymethamphetamine, MDMA; p-methoxyamphetamine, PMA; p-methoxymethamphetamine, PMMA; 4-methylthioamphetamine, 4-MTA; 3,4,5-trimethoxyamphetamine, TMA; 2,5-dimethoxy-4-iodoamphetamine, DOI) on extracellular levels of serotonin (5-HT) and dopamine (DA). Dialysates were assayed using HPLC equipped with electrochemical detector following i.p. administration with each drug at a dose of 5 mg/kg. MAP was found to drastically and rapidly increase 5-HT and DA levels (870% and 1460%, respectively). PMA, PMMA, and 4-MTA slightly increased DA levels (150-290%) but remarkably increased 5-HT levels (540-900%). In contrast, TMA and DOI caused no detectable changes in levels of both monoamines. We observed that the potent DA-releasing action of MAP was remarkably decreased by introduction of methoxy or methylthio group at the para position (MAP vs. PMMA or 4-MTA), but introduction of two additional adjacent methoxy groups into PMA totally abolished its 5-HT-/DA-releasing action (PMA vs. TMA). In addition, para-mono-substituted compounds inhibited both monoamine oxidase (MAO) enzymes more strongly than other compounds; PMA and 4-MTA exhibited submicromolar IC50 values for MAO-A. On the other hand, TMA scarcely affected the activity of both MAO enzymes as well as extracellular levels of 5-HT and DA. In this comparative study, MDMA, PMA, and 4-MTA functioned similar to PMMA, a typical empathogen; these findings therefore could be helpful in clarifying the psychopharmacological properties of amphetamine-related, empathogenic designer drugs.

Identification and phylogenetic analysis of hepatitis C virus in forensic blood samples obtained from injecting drug users.

Injecting drug users (IDUs) are a high-risk group for contracting hepatitis B virus (HBV), hepatitis C virus (HCV), and human immunodeficiency virus (HIV) infections. In Japan, data on the prevalence of those blood-borne viruses among IDUs are very limited. Blood samples were obtained from 12 cadavers of IDUs sent to Nagoya City University for the purpose of judicious autopsy and two alive IDUs with hepatitis C referred to a local hospital at the same period. The viruses were detected by polymerase chain reaction and phylogenetic analysis was performed. Two (16.6%) of the 12 autopsy cases were positive for HCV, but no case was positive for either HBV or HIV. Phylogenetic analysis of the two HCV isolates revealed that one was classified into genotype 1b and another was genotype 2b. Furthermore, nucleotide sequences of two isolates recovered from IDUs with hepatitis C were identical, that indicated the transmission of HCV between them, and those HCV were phylogenetically classified into genotype 2a. The prevalence of HCV infection among IDUs in Japan, despite the case of judicious autopsy, seems to be high, but HIV infection seems to be rare. The transmission of HCV between IDUs was demonstrated, and this indicates that phylogenetic analysis would applicable to also forensic analysis. HCV isolates identified in this study did not phylogenetically segregate, thus multiple transmission route of HCV among IDUs seems be exist in Japan.

Purification and characterization of diquat (1,1'-ethylene-2, 2'-dipyridylium)- metabolizing enzyme from paraquat-resistant rat liver cytosol.

To establish a paraquat-resistant Wistar rat strain, we carried out continuous sister-brother mating among rats that survived high-dose intraperitoneal administration of paraquat dichloride (360 mg/kg). The percentages of paraquat-resistant rats among wild rats and among the fifth-generations were 7.1% and 20.6%, respectively. After high-dose paraquat administration, the serum paraquat concentration in sensitive rats was much higher than that in paraquat-resistant rats. The cytosol fraction of liver from paraquat-resistant rats had higher paraquat- and diquat-metabolizing activities than that of liver from paraquat-sensitive rats. By contrast, microsomal fractions from livers of paraquat-resistant and paraquat-sensitive rats had no paraquat- or diquat-metabolizing activity. This paraquat/diquat-metabolizing enzyme was partially purified from paraquat-resistant rat liver cytosol using affinity chromatography for diquat. At the end of the purification procedure, rat liver diquat-metabolizing enzyme was purified 1154-fold to a final specific activity of 32.32 mol/h/mg protein, and an overall recovery of about 0.46% was obtained. This enzyme oxidized diquat to diquat-dipyridone during overnight incubation at 37 degrees C, but only metabolized traces of paraquat. The molecular mass of the enzyme was estimated as 190 kDa, and its isoelectric point of it was 4.6-4.7. Kinetic study revealed the values of K(m) and V(max) to be 35.0 micromol/l and 0.81 micromol/h/ml, respectively.