[A case of chronic idiopathic intestinal pseudoobstruction].
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Biomedical subjects
T Michimata
Publications and source records attributed to T Michimata.
Hypothyroidism enhances carbachol-induced hypothermia in the rat.
We studied cholinergic regulation of body temperature in hypothyroid rats. Thyroidectomy caused a progressive decrease in core temperature. Intraventricular injection of carbachol in a dose of 10 nmol did not change core temperature of the normal rat, whereas the same dose of carbachol significantly decreased the temperature of thyroidectomized rats. One hundred nmol carbachol decreased to a greater extent core temperature of the thyroidectomized rats than that of normal rats. Intraventricular injection of atropine significantly increased core temperature of thyroidectomized rats. The present data indicate that brain cholinergic mechanisms participate in controlling temperature in the hypothyroid status and thyroid hormones play a significant role in the brain cholinergic regulation of body temperature.
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Food deprivation decreases the blood TRH concentration in the rat.
Adult male rats were deprived of food for 1-6 days and the hypothalamo-pituitary axis in these rats was evaluated. Food deprivation caused a progressive decrease in TRH concentration in the peripheral blood with a concomitant reduction in the blood TSH level. No significant change was observed in the hypothalamic, extrahypothalamic or pancreatic TRH concentration between the control and starved groups. Starvation did not cause a significant change in the pituitary TRH receptors or the in vitro responsiveness of TSH to TRH. These data imply that the reduction in the blood TRH level may contribute in part to the decrease in the blood TSH level after food deprivation, but the origin of the blood TRH has remained to be determined.
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[Disappearance rate of TRH: change in the status of TSH refractoriness in vitro].
We studied on the potential change in TRH disappearance rate in the status of TSH refractoriness in vitro. TSH secretion from the rat anterior pituitaries progressively increased in the presence of TRH in doses between 0.2-20 ng/ml. In contrast, administration of TRH in a dose of 200 ng/ml decreased TSH secretion as compared to TRH in a dose of 20 ng/ml. Disappearance rate of 2 ng/ml TRH in incubation media increased as compared to that of 20 ng/ml TRH, but it was statistically similar between 20 and 200 ng/ml of TRH. Incubated TRH was indistinguishable from the authentic tripeptide on a HPLC. These data indicate that in vitro refractoriness of TSH response to TRH did not depend on the significant change in TRH disappearance rate.
Animals↗
[TRH and cyclo (His-Pro) concentrations in the young rat brain are altered by a liquid protein diet].
Effects of liquid protein diet (LPD), that is known to be poor in protein quality, on brain TRH and cyclo (His-Pro) concentrations were explored in young male rats. At day 23 of weaning, the animals were fed either a 20% casein diet ad libitum or a 20% LPD, or were pair-fed with a 20% casein diet. They were decapitated at day 35 or day 48. The body weight of those in the LPD group decreased significantly, and the loss was sustained in comparison with those in the pair-fed and ad libitum groups. The extrahypothalamic cyclo (His-Pro) concentrations were significantly greater in the LPD group than in the pair-fed and ad libitum groups throughout the experimental period, whereas these concentrations were similar in the pair-fed and ad libitum groups. At day 48, TRH concentrations in the hypothalamus and extrahypothalamus also increased in the LPD group in comparison with the concentrations in ad libitum group. These data indicate that quality of the protein component in the diet has a potential effect on alteration in the neuropeptides, TRH and cyclo (His-Pro), in the young rat brain.
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