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Biomedical subjects

T Sakata

Publications and source records attributed to T Sakata.

At least 559 records · Page 31Linked to original sources
PubMed1979

Rumen epithelium cell proliferation accelerated by propionate and acetate.

Ruminal papillae were biopsied from fasted adult sheep given 18 m mole/kg body weight per day of sodium propionate or sodium acetate intraruminally via fistula. The mitotic index of the epithelial cells in the papillae was estimated for the mitogenic effect of the acids. Before the administrations, mitotic indices were lower than .53%. They increased after a few days' propionate-administration, then declined. The peak values appeared on 2 or 4 days of the administration and were 1.64%, 1.38%, 1.73%, and 1.54% in four trials. Mitotic indices also increased from acetate and declined. The peak values appeared on 3 or 4 days of the administration and were 2.04%, 2.49%, 1.70%, and 2.03% in four trials. Mitotic indices of the control sheep given the same amount of .9% saline were lower than .28%. The mitogenic effect of propionate and acetate on the rumen epithelial cells was apparent, but it seems to be weaker than that of butyrate judged from the relatively slow rise of the index in this study.

Acetates↗
PubMed1978

Rumen epithelial cell proliferation accelerated by rapid increase in intraruminal butyrate.

Two pairs of adult castrated male sheep were given intraruminally 2 g/kg body weight per day of sodium n-butyrate rapidly 10 s at noon or slowly over 20 to 24 h from noon in four trials in which they received only mixed minerals and water ad libitum. Their ruminal papillae were biopsied just before each administration and 24 h after the final administration. Mitotic indices of the epithelial cells were observed. Mitotic indices were lower than .48% before butyrate administration. In sheep rapidly administered butyrate, mitotic indices increased to 1.29%, 2.33%, 2.65%, and 1.84% in 1 day after the first administration in four trials and tended to decline on later days. In sheep slowly administered butyrate, mitotic indices stayed lower than .50% and did not show significant fluctuations. Our data support our hypothesis that an increase in the rate of intraruminal production of volatile fatty acids promotes proliferation of epithelial cells of the organ.

Animals↗
PubMed1978

Presence of circadian rhythm in the mitotic index of the ruminal epithelium in sheep.

Mitotic indices of the ruminal epithelium of two castrated male sheep fed at 11:00 h were determined at 00:00, 04:00, 08:00, 12:00, 16:00 and 20:00 h. The schedules were repeated in four trials done in December 1975, February, March and June 1976 respectively. The indices ranged from 0.13 to 0.92 per cent, both animals showing a similar tendency in these fluctuations. The mean rate of cell division was low in the morning, high in the afternoon and in the evening, and declined at about midnight. Another pair of male castrated sheep were fed at 07:00, and rumen samples were biopsied six times in three days. The mean rate of epithelial cell division in the rumen was low at 08:00, but high at noon, suggesting that the rate possibly was affected by the food intake of the experimental animals.

Animals↗
PubMed1977

Light-dark patterns in running-wheel activity in rats during chronic administration of theophylline.

Running-wheel activity for 24 hr and activity patterns were studied during chronic theophylline administration. Theophylline altered the normal relations between activity level and illumination. Dark-time activity was decreased to approximately 50% and 24 hr activity was unaffected. These observations were consistent with previous results showing that theophylline suppressed dark-time feeding but had no effect on 24 hr food intake. A possible mechanism to account for these results may be dependent on levels and turnover of brain norepinephrine.

Animals↗
PubMed1976

[A shift to diurnal feeding following chronic administration of theophylline in rats].

Influence of chronic administration of theophylline on feeding behavior in rats was studied in contrast with the saline controls under a 12 hr light-dark cycle. The results obtained were as follows: 1) total amount of food intake per 24 hr was not affected by either chronic administration of theophylline or saline administration; 2) theophyllinized rats, however, ate more food during light time (0900-2100) and less food during the dark (2100-0900); 3) the amount of food intake during the dark in the control group was approximately 80% of total intake, while that in the theophylline group decreased to below 60%; 4) increase in ratios of body weights in the theophylline and the control groups did not differ significantly throughout the entire experimental period. Feeding behavior of the rat is closely correlated with a daily light-dark cycle as was seen in the control group. The feeding circadian pattern disappeared in theophyllinized rats, i.e., the behavioral characteristic of a nocturnal feeder could not be preserved following theophylline administration. The disappearance of the feeding cycle may result from a phase shift of the cycle, which was induced by facilitatory effects of theophylline on food intake during light time.

Animals↗
PubMed1975

Changes of brain serotonin and muricide behavior following chronic administration of theophylline in rats.

Temporal modification of amygdaloid serotonin (5HT) content and the resultant muricide behavior, compared to isolated and olfactory bulbectomized rats, were studied after chronic theophylline administration. Theophylline raised amygdaloid 5HT after Day 28 and amygdaloid 5-hydroxyindoleacetic acid (5HIAA), its deaminated metabolite, after Day 7. Theophylline applied for 29 days elevated 5HT and 5HIAA in the amygdala, the diencephalon and the brain stem, but not in the cortex. Effects of theophylline were reduced latency and maintained tendency to kill, even after overnight muricide test. The 5HT content of the amygdala decreased in bulbectomized rats. Discrepancy between brain 5HT changes and aggressive behavior were discussed.

Aggression↗