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Biomedical subjects

Y Kohno

Publications and source records attributed to Y Kohno.

At least 325 records · Page 18Linked to original sources
PubMed1982

Psychological stress enhances noradrenaline turnover in specific brain regions in rats.

Concentrations of noradrenaline (NA) and 3-methoxy-4-hydroxyphenylethyleneglycol sulfate (MHPG-SO4) in the hypothalamus, amygdala, cerebral cortex and pons + medulla oblongata were examined in male Wistar rats exposed to foot-shock or to psychological stress for 1 hour. Animals in the psychological stress group were prevented from receiving foot shock, but were exposed to responses of shocked rats. Foot shocked rats exhibited a significant reduction in NA content and a significant elevation in MHPG-SO4 level in all brain regions when compared to control rats which were neither shocked nor exposed to shocked rats. Rats exposed to the psychological stress displayed a significant reduction of NA level in the amygdala, significant elevation of MHPG-SO4 content in the hypothalamus and amygdala, and a moderate elevation of plasma corticosterone level. These results suggest that psychological stress produces mild enhancement of NA release preferentially in the hypothalamus and amygdala; while foot shock stress elicits a more intense response of noradrenergic neurons in more extended brain regions.

Amygdala↗
PubMed1982

Effects of age and stress on regional noradrenaline metabolism in the rat brain.

Levels of noradrenaline (NA) and its major metabolite, 3-methoxy-4-hydroxyphenylethyleneglycol sulfate (MHPG-SO4), were determined in eight brain regions of non-stressed rats at 2, 10 and 15 months of age, and of rats at 2 and 15 months of age stressed by immobilization for 3 hours. The NA levels in older rats were significantly lower in the hypothalamus, pons + med.obl. and midbrain, and higher in the amygdala, thalamus, hippocampus and cerebral cortex as compared to those of 2 month old rats. The MHPG-SO4 levels in the older rats were significantly lower in the hypothalamus, amygdala, pons + med.obl. and midbrain, and higher only in the cerebral cortex than those in 2 month old rats. Immobilization stress caused significant increases in NA turnover in all brain regions of both 2 and 15 month old rats. Age-related difference in the degree of stress-induced change in NA metabolism was found only in the hypothalamus; the increase of MHPG-SO4 by stress was greater in 2 month old rats than in 15 month old rats, although both age groups of rats showed the same degree of NA reduction by stress. These data suggest that brain NA metabolism changes in an age-related fashion, and that apparent regional differences exist in the pattern of these changes. Specifically, it appears that there is an age-related difference in the response of noradrenergic neurons to stress in the hypothalamus.

Aging↗
PubMed1982

Postnatal development of noradrenaline and 3-methoxy-4-hydroxyphenylethyleneglycol sulphate levels in rat brain regions.

Developmental changes in brain levels of noradrenaline (NA) and 3-methoxy-4-hydroxyphenylethyleneglycol sulphate (MHPG-SO4) were studied in rats. In most brain regions, MHPG-SO4 level rapidly increased to approach or exceed adult levels at the time of weaning, while NA levels increased more gradually and reached adult levels following weaning. Pharmacological studies showed that the MHPG-SO4 level in the neonatal brain reflects the degradation of released NA. The developmental characteristics of noradrenergic neurons in eight discrete brain regions are discussed.

Aging↗
PubMed1982

[Two-dimensional echocardiographic evaluation of the right ventricular wall in hypertension and hypertrophic cardiomyopathy].

The thickness and motion of the right ventricular wall (RVW) were studied with two-dimensional echocardiography from a subxiphoid approach in 20 normal subjects (N Group), 86 patients with hypertension (HT Group) and 20 patients with hypertrophic cardiomyopathy (HCM Group). Comparison was made between the patients with and without echocardiographic RVW hypertrophy in each patient group in regard to the thickness of the interventricular septum (IVS) and the left ventricular posterior wall (LVPW) as well as the motion of the RVW and cardiac catheterization data. 1. RVW hypertrophy was visualized in 39.5% of the HT Group and in 40% of the HCM Group. There was no difference in the thickness of RVW between the two groups. 2. A localized hypertrophy and an abnormal motion of RVW were obtained in the HCM Group, but not in the HT Group. 3. RVW hypertrophy in the HT Group was seen in patients with marked IVS hypertrophy, while that in the HCM Group was not related to IVS hypertrophy. 4. Pulmonary arterial pressure remained normal in each group. Therefore, RVW hypertrophy did not appear to be the result of pressure overload. 5. Right atrial mean pressure and right ventricular end-diastolic pressure were elevated only in HCM patients with RVW hypertrophy. We conclude that there is a different mechanism in the mode of production of RVW hypertrophy between patients with hypertension and those with hypertrophic cardiomyopathy.

Cardiac Volume↗
PubMed1981

Involvement of noradrenergic and dopaminergic neurons in shock-induced jumping in rats.

The role of central noradrenergic and dopaminergic neurons in shock-induced jumping behavior in the rat was examined using specific stimulants and blockers of the respective receptors. The administration of the alpha-noradrenergic receptor stimulant, clonidine, increased jumping frequency (10-100 micrograms/kg) and reduced latency (100-500 micrograms/kg). The effects of clonidine were counteracted by the postsynaptic alpha-adrenoceptive blocking agent, phenoxybenzamine (20 mg/kg). The dopaminergic receptor stimulant, apomorphine (0.1-5.0 mg/kg), did not increase jumping frequency, but prolonged jumping latency. On the other hand, combined administration of clonidine (30, 500 micrograms/kg) and apomorphine (2 mg/kg) increased jumping behavior more remarkably than did clonidine alone. The blockers of postsynaptic alpha-noradrenergic and dopaminergic receptors, phenoxybenzamine (20 mg/kg) and pimozide (2 mg/kg) respectively, had little effect on jumping when used alone, but each drug counteracted the enhanced jumping response caused by clonidine plus apomorphine. Combined administration of phenoxybenzamine and pimozide depressed jumping. These data suggest that excitation of dopaminergic neurons exerts a positive modulating effect on the noradrenaline-mediated jumping behavior induced by foot-shock.

Animals↗
PubMed1981

Regional responses of rat brain noradrenergic neurones to acute intense stress.

Contents of noradrenaline (NA) and its principal metabolite, 3-methoxy-4-hydroxyphenylethyleneglycol sulfate (MHPG-SO4), in six brain regions of the rat were monitored simultaneously during 180 min of acute intense stress, i.e., electric tail shock under immobilization. In the hypothalamus and amygdala, NA contents decreased rapidly, and subsequently remained at the decreased levels while MHPG-SO4 contents increased progressively. The hippocampus and cerebral cortex showed more delayed changes in NA and MHPG-SO4 contents than the above regions. In the pons+med. obl., no decreases of NA contents were observed at any time, but MHPG-SO4 contents increased significantly. Neither NA nor MHPG-SO4 content changed significantly in the basal ganglia except for a transient increase of NA. These results suggest that, during acute intense stress, each brain region responds differently and the NA content is maintained at a decreased level despite continuously enhanced release of the amine.

Animals↗
PubMed1981

Regional distribution and production rate of 3-methoxy-4-hydroxyphenylethyleneglycol sulphate (MHPG-SO4) in rat brain.

The levels of noradrenaline (NA) and 3-methoxy-4-hydroxyphenylethyleneglycol sulphate (MHPG-SO4) in 15 brain regions showed a parallel distribution in male Wistar rats. The differences in regional distribution of MHPG-SO4 were similar to those in the rate of NA turnover reported by other investigators. The accumulation rates of MHPG-SO4 during 45 and 90 min after probenecid injection significantly correlated to the steady state levels of MHPG-SO4 in nine regions studied. With the results, the regional levels of MHPG-SO4 either in untreated or in probenecid-treated rats, are considered to be a useful index of NA turnover.

Animals↗