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N Mataga

Publications and source records attributed to N Mataga.

45 records · Page 3Linked to original sources
PubMed1983

Behavioral sensitization and relative hyperresponsiveness of striatal and limbic dopaminergic neurons after repeated methamphetamine treatment.

Rats were used in a study of the effects of repeated methamphetamine treatment on stereotyped behavior and striatal and limbic dopamine metabolism in response to challenge with the drug or other dopamine agonists. Repeated administration of d-methamphetamine (6 mg/kg per day for 3-14 days) produced long-term behavioral sensitization (augmented response to a challenge injection) not only to the compound (at 44-89 days after drug withdrawal) but also to apomorphine and nomifensine. Even a single injection of d-methamphetamine (6 mg/kg) enhanced the behavioral response to the drug. A challenge dose of d-methamphetamine (2 mg/kg) markedly increased dopamine turnover (lower dopamine and higher 3,4-dihydroxyphenylacetic acid levels, higher ratios of 3,4-dihydroxyphenylacetic acid over dopamine) in the striatum and mesolimbic area of the sensitized animals on day 15 of withdrawal from treatment repeated for 14 days with the drug (6 mg/kg per day). These findings demonstrate that behavioral sensitization induced by methamphetamine is accompanied by increased central dopaminergic transmission.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1982

Dopamine metabolism increases in post-mortem schizophrenic basal ganglia.

The dopamine-rich regions of post-mortem brains from 6 schizophrenics and 7 controls were analyzed. There were no significant changes in dopamine concentrations in basal ganglia and nucleus accumbens of schizophrenics compared with controls. Schizophrenic basal ganglia (putamen and caudate) showed significantly higher levels of homovanillic acid, and tyrosine hydroxylase activity. Among the schizophrenic patients, markedly high activity of tyrosine hydroxylase was measured in a patient diagnosed as catatonic type. He had not taken antipsychotic drugs for 3 months prior to death. In his relatives, three other schizophrenics were found to the second degree. A remarkable low level of dopamine and a high level of homovanillic acid measured indicate this case would have had an increased turnover rate of dopamine in the dopaminergic nerve terminals. Among the schizophrenic patients, there might be one group whose enzyme activity of dopamine synthesis in the brain is exceptionally high.

Adult↗
PubMed1982

Dynamic depolarization of interacting fluorophores. Effect of internal rotation and energy transfer.

Effects of internal rotation on the fluorescence decay functions and time-dependent anisotropies of fluorophores bound to a spherical macromolecule are theoretically investigated in the presence of the intramolecular energy transfer interaction by solving relevant rotational diffusion equations. The model system examined is one in which the energy donor is internally rotating around an axis fixed at the macromolecule and the acceptor is fixed at a definite position in the macromolecule. The effect of internal rotation in the system is described by Hill's functions with two cosine terms. The fluorescence decay function and anisotropy decay are functions of the ratio of energy-transfer probability averaged over the internal rotation angle to the rotary diffusion co-efficient. When the internal rotation is much faster than energy transfer, the decay function of the donor is predicted to be a single exponential, and the anisotropy decay is essentially described by the expression derived by Gotlieb and Wahl (1963. J. Chim. Phys. 60:849-856). However, deviation from it becomes pronounced as the rotation becomes slower. Methods of numerical analysis are presented for decay function and anisotropy decay, as well as relative quantum yield and polarization anisotropy under steady-state excitation, and examined for a simplified system under the variation of the diffusion coefficient.

Energy Transfer↗
PubMed1981

Enhancement of haloperidol-induced increase in rat striatal or mesolimbic 3,4-dihydroxyphenylacetic acid and homovanillic acid by pretreatment with chronic methamphetamine.

After a drug-free period of 1 week following 2 weeks of haloperidol treatment, the increased response of striatal 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) to a challenge dose of haloperidol was significantly reduced. Tolerance to this effect was not, however, seen in the mesolimbic system. Pretreatment of the rats with methamphetamine (MAP) for 8 days prior to chronic haloperidol significantly enhanced the DOPAC and HVA increase produced by the challenge with haloperidol in both brain areas. The reduced response of striatal DOPAC or HVA after chronic haloperidol was prevented by pretreatment with MAP. The data suggest that the long-term dopamine receptor stimulation induced by MAP may antagonize the tolerance produced by chronic haloperidol treatment.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1977

Laser photolysis and fluorescence studies on pyrene-thiazide and pyrene-diazoxide systems.

The laser photolysis studies on pyrene, pyrene-thiazides and pyrene-diazoxide systems in acetonitrile revealed that thiazides and diazoxide can scavenge the photoejected electron. It was found that the pyrene fluorescence is quenched by the present diuretics and related compounds and both static and dynamic quenching constants were obtained. Thiazides quench the fluorescence through both static and dynamic mechanism, while the small static quenching constant and no lifetime shortening of pyrene were observed in the case of diazoxide quencher. This difference may correspond to the difference of their diuretic activity.

Diazoxide↗