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Biomedical subjects

H Uchimura

Publications and source records attributed to H Uchimura.

At least 109 records · Page 6Linked to original sources
PubMed1983

Differential effects of acute and chronic administration of haloperidol on homovanillic acid levels in discrete dopaminergic areas of rat brain.

After acute administration of haloperidol, homovanillic acid (HVA) levels were increased in the prefrontal cortex, anterior cingulate cortex, discrete limbic areas and A14 dopamine (DA) neurons. The maximal effect of haloperidol was attained more slowly in the prefrontal cortex and amygdala than in the other regions. The ED50 of haloperidol was 0.03 mg/kg in the prefrontal cortex, but was 0.06-0.07 mg/kg in other areas examined. After repeated administration of haloperidol, tolerance to the HVA increase was observed in the striatum and all limbic areas examined, the amygdala being the most susceptible to this tolerance. In contrast, no tolerance was found in the anteromedial and suprarhinal DA neurons of the prefrontal cortex and A14 DA neurons. These results suggest that the prefrontal cortex may be a possible site for the antipsychotic action of haloperidol. On the other hand, no change of HVA levels in the A12 and A13 DA neurons of the hypothalamus was observed after haloperidol treatments, suggesting a lack of neuronal feedback mechanism in the A12 and A13 DA neurons.

Animals↗
PubMed1983

Dopamine, serotonin and alpha-adrenergic receptor blocking activities in serum and their relationships to prolactin level in schizophrenic patients receiving long-term chlorpromazine treatment.

The clinical application of a dopamine radioreceptor assay for neuroleptics has been proposed. Simultaneous monitoring of serum antidopaminergic (anti-DA), antiserotonergic (anti-5HT) antiadrenergic (anti-NA) activities may provide a better understanding of clinical effects of neuroleptics. Serum anti-DA and anti-5HT activities were estimated by competition for 3H-spiperone binding to dopamine and serotonin receptors in rat brain, respectively, and anti-NA activity by competition for 3H-WB-4101 binding to alpha-receptors. Thirty-one patients receiving maintenance doses of chlorpromazine (CPZ) chronically were studied. Serum activities varied among patients receiving the same dose, but correlated significantly with dose. Anti-DA activity also correlated with both anti-5HT anti-NA activities, and the average ratio of anti-5HT or anti-NA to anti-DA activity was slightly reduced by metabolism of CPZ. However, some patients had a different spectrum of serum activities from that of in vitro activities. Serum prolactin (PRL) correlated weakly with all the serum activities. The serum PRL anti-DA activity ratio appeared to be independent of anti-5HT or anti-NA activity, suggesting the predominant involvement of anti-DA activity in the stimulation of PRL release.

Adrenergic alpha-Antagonists↗
PubMed1983

Effects of prolonged administration of thyrotrophin on serum concentration, release and synthesis of thyroid hormones in mice.

Mice were injected sc with TSH (0.5 U) at 12 h intervals for 5 days. Groups of mice were sacrificed daily to determine serum T4 and T3 concentrations, 4 h thyroidal 125I uptake, distribution of 125I among thyroidal iodoamino acids, and thyroidal content of T4 and T3. Serum T4 and T3 concentrations increased significantly after the initial injection of TSH and gradually decreased thereafter, reaching initial levels on the 3rd and 4th days, respectively. In contrast to serum hormone levels, thyroidal 125I uptake, incorporation of 125I into T4 and T3 increased significantly on the first day and remained elevated throughout the period of TSH-treatment. Thyroidal T4 content expressed as microgram/mg weight of tissue decreased significantly on the first day and thereafter remained constant. Thyroidal T3 content did not change significantly throughout the experimental period. The differences between thyroidal synthesis and thyroidal contents of T4 and T3 strongly suggest that thyroid hormone secretion is being continuously stimulated. Transient increases in serum T4 and T3 concentrations are probably due to a gradual increase in the rate of peripheral degradation of thyroid hormones. These results suggest that TSH-induced refractoriness in thyroidal iodine metabolism does not appear to exist, at least when TSH is given in vivo for 5 days.

Animals↗
PubMed1983

Chronic effect of TSH on human thyroid tissue in organ culture.

The chronic effect of TSH on thyroidal cAMP concentrations and release of thyroid hormones was investigated using human thyroid tissue in organ culture. Normal human thyroid slices were placed in HAM's F-10 synthetic culture medium in Falcon organ tissue culture dishes, and incubated at 37 degrees in a humidified atmosphere of 5% CO2 in air. Medium was changed everyday and daily T3 or T4 release was determined using concentration of T3 or T4 in the medium. After incubation, slices were transferred to the medium containing 10 mM theophylline and incubated without TSH for an additional 30 min to determine thyroidal cAMP concentrations. Thyroidal cAMP concentrations in slices incubated with 10 mU/ml of TSH increased significantly at 2, 6, and 24 hr and even on the 6th day of incubation. Daily T3 release was significantly increased above control from the 3rd day and daily T4 release from the 4th day to the 11th day of incubation with 10 mU/ml of TSH. Histologically, almost all follicles were structurally maintained even on the 11th day of incubation. These results suggest that both thyroidal cAMP concentrations and release of thyroid hormones are stimulated chronically by TSH. This organ culture system is useful for investigating chronic effects of various materials on human thyroid tissue.

Cyclic AMP↗
PubMed1982

Mass fragmentographic determination of homovanillic acid in individual dopaminergic neuron systems of rat brain: application of reaction gas chromatography.

Homovanillic acid (HVA) levels of 12 discrete rat brain areas were determined by a mass fragmentographic method using the reaction gas chromatographic technique. The use of reaction gas chromatography increased the sensitivity for determination of HVA. The sensitivity of this method allows measurement of HVA in small amounts of brain tissue. The HVA levels in polar, medial, and lateral fields of prefrontal cortex, anterior cingulate cortex, septum, amygdala, A12, A13, and A14 dopaminergic neurons were 0.417 +/- 0.018 ng/mg protein, 0.689 +/- 0.004, 0.753 +/- 0.024, 0.496 +/- 0.029, 1.311 +/- 0.046, 0.555 +/- 0.008, 1.949 +/- 0.077, 1.109 +/- 0.112, and 0.489 +/- 0.019, respectively. The HVA levels in these areas are first reported in the present paper.

Animals↗