Methamphetamine-induced behavioral effects and releases of brain catecholamines and brain concentrations of methamphetamine in mice

The characteristic behavioral effect of methamphetamine (MA) at 2.5 mg/kg was enhanced locomotor activity which lasted over 2.5 hr. At 10.0 mg/kg MA, stereotyped behavior was predominant and lasted over 3 hr. The behavioral effect of 5.0 mg/kg MA was of the mixed type. MA at 5.0 and 10.0 mg/kg lowered the brain NE level from 2 hr after drug treatment, while the accumulation of MHPG-SO4 was increased over 2 hr at 2.5 and 5.0 mg/kg MA. The accumulation of HVA was significantly increased at 10.0 mg/kg MA over 3 hr. Accordingly, the behavioral effects of MA at the earlier period were compatible with the biochemical effects of MA. The behavioral effects during the 2- to 4-hr period, however, seem to be unrelated to the actions on brain catecholamines. Measurement of brain MA concentrations revealed that approx. 2 micrograms/g in the brain may be necessary to produce enhanced locomotor activity and the increased accumulation of brain MHPG-SO4. It appeared that approx. 8 to 9 micrograms/g MA in the brain was required to produce characteristic stereotyped behavior and the increased accumulation of HVA. Therefore, the behavioral and biochemical effects of MA were correlated with the brain MA concentrations.

Synthesis of S-adenosylmethionine synthetase isozymes from rat and mouse livers. Immunochemical studies

The alpha- and beta-forms of S-adenosylmethionine synthetase in rat liver were completely fractionated by chromatography on a hydrophobic resin, phenyl-Sepharose. The alpha-form was eluted in low-ionic strength buffer, and the beta-form was eluted with 50% dimethylsulfoxide. The alpha-form is less sensitive to dimethylsulfoxide, whereas the beta-form is strikingly stimulated by dimethylsulfoxide, after removal of the dimethylsulfoxide. The levels of the alpha-form activity in rat liver after treatment with ethionine and adenine for 2 consecutive days, and those of the beta-form activity in mouse liver on the 12th day after transplantation of Ehrlich ascites tumor cells, were increased several fold compared to normal liver. Immunochemical titrations with specific antibody against the beta-form as well as kinetic studies indicated that the observed increase in the levels of each activity from the S-adenosylmethionine synthetase isozymes is due to an increase in the cellular content of the enzyme.

Effects of ethanol on catecholamine levels and related enzyme activities in different brain regions of rats

The effects of ethanol on the contents of norepinephrine (NE) and dopamine (DA) and the activities of related enzymes in the various regions of rat brains with different doses and mode of administration of ethanol were investigated. In acute ethanol intoxication, steady-state levels of NE were not altered. Continuous ethanol intoxication, however, significantly reduced NE contents and tended to decrease the activity of dopamine-beta-hydroxylase in the hippocampus. The decrease in NE contents became more significant during ethanol withdrawal, especially in the medulla oblongata and the striatum. DA contents were increased in the brain-stem region in all ethanol-treated rats. The increase in DA contents correlated with the increase in tyrosine hydroxylase activity. The present data suggest that the dopaminergic system may contribute to the development of physical dependence on ethanol.

Effects of brain biogenic amines on ethanol withdrawal reactions and the development of ethanol dependence in mice

Mice were made physically dependent on ethanol by a four-day period of ethanol inhalation. A single injection of L-dopa tended to enhance ethanol withdrawal reactions and 5HTP tended to suppress it. Daily treatment with PCPA and L-dopa or pretreatment with 6OHDA tended to modify the severity of withdrawal reactions. PCPA slightly decreased the severity, 6OHDA tended to aggravate the severity, and L-dopa tended to decrease the severity. The simultaneous estimation of brain biogenic amine levels suggests that 5HT and DA may be involved in the development of physical dependence on ethanol. Treatment with neuropharmacological drugs during ethanol withdrawal modified the severity of ethanol withdrawal reactions. Pentobarbital and diazepam completely suppressed ethanol withdrawal reactions. GHBA and reserpine suppressed the severity and haloperidol, imipramine, and methylphenidate aggravated it. The simultaneous estimation of brain catecholamine levels suggests that suppression of ethanol withdrawal reactions consistently results from the decreased activities of either noradrenergic or dopaminergic neurons. However, the effects of biogenic amines on ethanol withdrawal reactions may be different from those on the development of physical dependence on ethanol.

Preferential inhibition of the B-form of monoamine oxidase in the liver of rats given 3'-methyl-4-dimethylaminoazobenzene in the diet

A and B-form monoamine oxidase (MAO) activities were measured in the liver of rats maintained with a diet containing 0.06% 3'-methyl-4-dimethylaminoazobenzene (3'-Me-DAB). A-form MAO activity was similar to the control value throughout the feeding periods with serotonin as substrate. In contrast, B-form MAO activity decreased rapidly and the level of MAO activity was maintained at about 30% with beta-phenylethylamine (beta-PEA) as substrate. 3'-Me-DAB feeding did not cause any changes in MAO activity in the brain of rats. A single administration of 3'-Me-DAB (100 mg/kg p.o.) failed to alter A and B-form MAO activities for up to 4 days after its administration. The mechanism of inhibition of B-form MAO activity in rat liver mitochondria by 3'-Me-DAB was investigated. The inhibition of 3'-Me-DAB of B-form MAO activity, in vitro, was competitive and reversible. There was no difference in the apparent Michaelis constant toward beta-PEA between control and 3'-Me-DAB fed rats. B-form MAO in rat liver mitochondria was titrated with (-)deprenyl; this compound is selective to and an irreversible inhibitor of B-form MAO. The content of B-form MAO in liver mitochondria of rats fed 3'-Me-DAB for 3 weeks was decreased to about 60% of the control level.

Further studies on the synthesis of A-form monoamine oxidase

The relation between precursors and restoration of A-form MAO activity in rat liver after administration of clorgyline to rats was investigated by measuring the rates of recovery of A-form MAO activity after treatment with the inhibitor. The half-lives of mitochondrial and microsomal A-form MAO were estimated as 3.5 and 2.0 days, respectively. MAO activity and the amount of MAO molecules were completely restored within 14 days. However the values attained did not exceed the control values in a period of 14 days. Clorgyline plus cycloheximide or chloramphenicol did not prevent the recovery of MAO activity in the microsomes, but did not delay the appearance of enzyme activity in the mitochondria. A and B-form-like MAO were also observed in the microsomal and supernatant fractions, with clorgyline as inhibitor. These results suggest that the microsomal enzyme is a precursor of the mitochondrial enzyme, that the levels of A-form and B-form MAO are regulated genetically, and that the two forms of MAO may be synthesized separately.

Experimental gingivitis in ODU plaque-susceptible rats. V. On the vascular permeability factor of dental plaque

Plaque-induced inflammation has been documented from various aspects, but is still not well understood. In an effort to clarify the physicochemical properties of dental plaque and to isolate the active factor which give rise to inflammation, we studied a factor in plaque which may be a direct and local cause of gingival inflammation in ODU rats. Rat dental plaque was dissolved in physiologic saline. After being homogenized, the solution was centrifuged and the supernatant (RP) was used as a sample. Protein component (pRP) of PR was isolated by ammonium sulfate fractionated procedure and then deproteinized RP (dpRP) was obtained by trichloroacetic acid treatment. The vascular permeability factor existed in RP and it was affected by heating and pH. Changes in vascular permeability were directly proportionate to the logarithm of the concentration of protein fraction in dental plaque, and were of a delayed type. It was surmised that pRP contained in RP was the main vascular permeability factor, and it was purified by gel filtration on Sephadex G-100 and G-200.