Effect of Triiodothyronine Injection on Levels of Triiodothyronine and Thyroid-Stimulating Hormone in Sera and Milk of Lactating Rats and in Sera of Their Sucklings;Precocious Development of Jejunal α-Disaccharidases in the Sucklings

Koldovský, Otakar; Krulich, L.; Tenore, Alfred; Jumawan, Jocelyn; Horowitz, Carolyn; Lau, Herbert

doi:10.1159/000241262

Cited by 16 publications

(8 citation statements)

References 11 publications

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“…Taken together with previous data (8,(13)(14)(15)(16)(17)(20)(21)(22)34), this suggests that there are two phases in the ontogeny of this enzyme: (1) an early phase in which the appearance of the enzyme is cued by corticosterone and facilitated by thyroxine; and (2) a later phase in which the terminal maturation of the enzyme is dependent on the composition of the diet. The exact duration of these two phases has not yet been established.…”

Section: Discussionsupporting

confidence: 81%

“…The details of these enzymic changes and their irnportance in the dietary transition from milk to solid food have been frequently reviewed (6,15,16,19,27). There is good evidence to indicate that the enzymic changes are cued by the glucocorticoid (4,8,14,15,16,18,22) and the thyroid (13,20,21,34) hormones. Although there is a temporal correlation between the maturation of the intestinal mucosa and the spontaneous process of weaning, the possibility that the ontogenic changes in the intestine are diet initiated has generally been discredited (4,10,17,23).…”

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confidence: 99%

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Role of Diet in the Determination of Jejunal Sucrase Activity in the Weanling Rat

Henning

Guerin

1981

Pediatr Res

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SummaryThis study was designed to determine the critical difference between rat milk and rat chow with respect to their effects on jejunal sucrase activity during the fourth postnatal wk. Rats were weaned onto special diets on postnatal day 17, and jejunal sucrase was assayed on day 28. A pelleted diet containing lactose as sole carbohydrate did not cause depression of sucrase activity. Sucrase values (pmoles/hr/mg protein) were 10.49 k 0.81 (n = 15) for the lactose chow and 6.65 + 0.29 (n = 16) for the sucrose chow. This indicates that the nature of the dietary carbohydrate does not account for the sucrase differences of weaned and nonweaned animals. Likewise, the physical consistency of the diet is unimportant because sucrase values were just as high on a liquid diet (10.91 f 0.77 pmoles/hr/mg protein; n = 8) as on the solid diets. However, when the relative proportions of carbohydrate and fat in the diet were varied, there were significant effects on sucrase activity; values on a low carbohydrate diet (4.30 k 0.33 pmoles/ hr/mg protein; n = 8) being less than one-half those on a high carbohydrate diet (10.91 + 0.77 pmoles/hr/mg protein; n = 8). SpeculationThe terminal maturation of jejunal sucrase is dependent on the normal process of weaning. The critical feature of the weanling diet is that it is a high-carbohydrate, low-fat diet. In the absence of this dietary transition, intestinal development remains incomplete.The postnatal development of the rat small intestine is characterized by an array of enzymic changes during the third wk of life. Some enzymes (such as lactase and the lysosomal hydrolases) which have high activities at birth, decline at this time; others (such as maltase and sucrase) show dramatic increases in their activities. The details of these enzymic changes and their irnportance in the dietary transition from milk to solid food have been frequently reviewed (6,15,16,19,27). There is good evidence to indicate that the enzymic changes are cued by the glucocorticoid (4,8,14,15,16,18,22) and the thyroid (13,20,21,34) hormones. Although there is a temporal correlation between the maturation of the intestinal mucosa and the spontaneous process of weaning, the possibility that the ontogenic changes in the intestine are diet initiated has generally been discredited (4,10,17,23). For instance, rat pups which are prevented from weaning show an initial rise of jejunal sucrase at 17 days of age, just as in control pups (17). However, the same study showed that by the fourth postnatal wk, diet is an important determinant of sucrase activity. In control (weaned) pups, sucrase activity had plateaued at adult levels by day 27, whereas nonweaned pups had enzyme activities less than one-half those of controls and equivalent to activities usually seen on approximately day 20 (17). Thus, it seems that the normal process of weaning is necessary for the terminal maturation of jejunal sucrase activity. The aim of the current study was to determine the critical feature of the dietary change from milk to chow whic...

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Section: Discussionsupporting

confidence: 81%

mentioning

confidence: 99%

Role of Diet in the Determination of Jejunal Sucrase Activity in the Weanling Rat

Henning

Guerin

1981

Pediatr Res

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“…It is now well established that maturation of sucrase in the weanling rat is at least in part under hormonal control [20]. Injections of corticosteroids [13] or thyroxine [25] in suck ling pups elicit the precocious appearance of enzymatic activity in the jejunum. In experi mental diabetes with endogenous hyperglu-cagoncmia, sucrasc activity was shown to be enhanced [33] but repeated administration of exogenous glucagon to adult rats during 5 days failed to increase jejunal disaccharidase activities [10].…”

Section: Discussionmentioning

confidence: 99%

Pancreatic Glucagon Does not Alter Mucosal Growth and Maturation of Sucrase and Thymidine Kinase Activity in Rat Small Intestine

Buts¹,

Maldague²,

Meyer³

et al. 1983

Neonatology

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In order to determine whether pancreatic glucagon may influence growth of the small bowel mucosa and maturation of villous and crypt cell enzymes in orally fed rats, the hormone was administered daily to suckling pups from day 11 to day 14 (50 μg/day) and to weanling rats from day 12 to day 29 (100 μg/day) post partum. The control groups received, following the same schedule, an equal volume of 0.9% saline or of a glucagon diluent containing 0.2% phenol and 1.2% glycerine. In suckling pups treated with glucagon, sucrase and thymidine kinase activities were similar to those of the controls. During weaning, both glucagon- and diluent-treated rats grew slowlier (p < 0.05) than did saline controls. Histological examination of pancreatic -tissue sections from glucagon-treated rats showed partial or complete degranulation of the acinar cells. Compared to saline-treated controls, mucosal weight, protein and DNA per centimetre of gut remained unchanged in the duodenum, jejunum and ileum of glucagon-treated rats. However, these parameters were markedly depressed (p < 0.01) in animals treated with diluent. Prolonged treatment with glucagon during weaning had no effect on villus height, epithelial morphology and thymidine kinase activity but produced a decrease in both specific and total sucrase activity in the proximal intestine to levels about 50% (p < 0.01) of the saline controls. It is concluded that: (1) the administration of exogenous pancreatic glucagon does not induce early villous and crypt cell enzyme activity in the suckling rat; (2) at the given doses, the hormone does not impair the adaptation of the small intestine mucosa which occurs at weaning.

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“…In Infants, rats and lambs, suckling could affect plasma thyroid hormone levels (Stbrak et al, 1978 ;Koldovsky et al, 1980 ;Wrutniak and Cabello, 1987a) ; moreover, milk ingestion was generally lower in hypotrophic than in control lambs ; therefore, all the animals were removed from mothers and received limited amounts of a bovine colostrum pool in order to limit this variability (2.5 g/100 g birthweight 4, 8, 12, 16, 20, 24, 28 and 32 h post-partum and thereafter artificial milk ad libitum).…”

Section: Introductionmentioning

confidence: 99%

Neonatal changes in plasma cortisol, free and total iodothyronine levels in control and hypotrophic lambs

Wrutniak¹,

Cabello²

1987

Reprod. Nutr. Dévelop.

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Summary. Neonatal changes in plasma free and total iodothyronines, cortisol, glucose and urea levels have been studied in 8 control (birthweight a 2.5 kg) and 16 hypotrophic lambs (birthweight < 2.5 kg) receiving limited amounts of colostrum during the first 36 h of life and then fed ad libitum. During the period of colostrum feeding, plasma glucose levels were low in both groups and increased after the onset of ad libitum feeding ; they were significantly lower in hypotrophic animals from birth to 36 h. Plasma urea levels increased during the period of colostrum feeding and decreased thereafter in all animals. At birth, they were significantly higher in hypotrophic lambs.Over the entire period studied (20 d), plasma levels of total T4, free T4, total T3 and free T3 were markedly lowered in hypotrophic lambs without alterations in the values of the T3/free T4 ratio. No differences could be observed in plasma reverse T3 and cortisol levels. For all blood parameters recorded, the neonatal changes were parallel in the two groups of lambs.In agreement with hypoglycemia and hyperuremia observed at birth in hypotrophic lambs, with the litter size recorded for each experimental group and with previous results, placental insufficiency linked to a large litter size gestation could be at the origin of low thyroid hormone levels.Introduction.

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Effect of Triiodothyronine Injection on Levels of Triiodothyronine and Thyroid-Stimulating Hormone in Sera and Milk of Lactating Rats and in Sera of Their Sucklings;Precocious Development of Jejunal α-Disaccharidases in the Sucklings

Cited by 16 publications

References 11 publications

Role of Diet in the Determination of Jejunal Sucrase Activity in the Weanling Rat

Role of Diet in the Determination of Jejunal Sucrase Activity in the Weanling Rat

Pancreatic Glucagon Does not Alter Mucosal Growth and Maturation of Sucrase and Thymidine Kinase Activity in Rat Small Intestine

Neonatal changes in plasma cortisol, free and total iodothyronine levels in control and hypotrophic lambs

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