Modulation by Thyroxine of the Amount of
Lactase Protein in the Jejunum of Adult Rats

E, Nsi Emvo; Jf, Launay; Raul, Françis

doi:10.1159/000469295

Cited by 4 publications

(2 citation statements)

References 13 publications

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“…These results are in good accordance with previous reports which showed: serum T 3 and T 4 levels were reduced in starved rats as compared to those of non-starved rats ( 22 ), lactase activity was elevated in starved rats when serum T3 and T4 levels were reduced, and the enhancement of lactase activity in starved rats was repressed by i.p. injection of T4 (8,23).…”

Section: Discussionmentioning

confidence: 99%

Dietary Sucrose Enhances Intestinal Lactase Gene Expression in Euthyroid Rats

Kuranuki

Mochizuki

Goda

2006

J Nutr Sci Vitaminol

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Summary It is postulated that dietary carbohydrates and thyroid hormones are major regulators for expression of the lactase/phlorizin hydrolase (LPH) gene in rat jejunum. In this study, we investigated the effects of thyroid hormones and dietary sucrose on LPH gene expression and lactase activity in starved rats. Firstly, animals at 8 wk of age were fed a lowstarch diet (5.5% energy as cornstarch) or high-starch diet (71% energy as cornstarch) for 7 d (experiment 1). The mRNA level of LPH as well as lactase activity significantly decreased in rats fed the low-starch diet as compared to those fed the high-starch diet. To investigate the effects of thyroid hormone status, the animals previously fed the low-starch diet were starved for 3 d, and half of the animals were given intraperitoneal (i.p.) injections of 20 g/ 100 g body weight triiodothyronine (T 3 ) twice daily (experiment 2). The LPH mRNA level and lactase activity were elevated by starvation for 3 d, but they were repressed by the injection of T 3 during starvation. To investigate the effects of dietary sucrose in starved rats, they were force-fed a sucrose diet for 6 h (experiment 3). The LPH gene expression and lactase activity were up-regulated by force-feeding a sucrose diet, only when the animals were kept in euthyroid status by daily T 3 administrations. In contrast, the sucrase-isomaltase mRNA levels and sucrase activity were unaffected by force-feeding the sucrose diet for both T 3 -treated and untreated starved rats. Our work suggests that dietary sucrose is capable of enhancing lactase gene expression in starved rats when they have a sustainable thyroid hormone level.

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Section: Discussionmentioning

confidence: 99%

Dietary Sucrose Enhances Intestinal Lactase Gene Expression in Euthyroid Rats

Kuranuki

Mochizuki

Goda

2006

J Nutr Sci Vitaminol

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“…The most commonly held hypothesis for these changes involves intestinal motor activity. Studies on ITT using barium meals (Shier 1933, Shafer et al 1984, Bozzani et al 1985 or the pulmonary excretion of H, after ingestion of a non-absorbable carbohydrate such as lactulose (Bronk & Parson 1965, Emvo et al 1986) had in fact provided evidence for accelerated intestinal transit in hyper¬ thyroidism and decreased intestinal motility in hypo¬ thyroidism. In keeping with the literature, the present results indicate that ITT, as measured using carmine red, was longest in the hypothyroid animals.…”

Section: Discussionmentioning

confidence: 99%

Thyroxine effect on intestinal Cl−/HCO3− exchange in hypo- and hyperthyroid rats

Tenore¹,

Fasano²,

Gasparini³

et al. 1996

Journal of Endocrinology

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Changes in transepithelial water and electrolyte transport as causative or contributing factors of the diarrhoea and constipation found associated with changes in thyroid physiology were studied. Albino Wistar rats were pharmacologically made either hypothyroid or hyperthyroid. After sacrifice, the small intestine was mounted in Ussing chambers in order to measure in vitro ion net fluxes under short-circuit conditions. Hypothyroid animals showed an increase in intestinal transit time, Cl- absorption (mainly due to an increment in its mucosal to serosal component) and residual ion flux (which is believed to represent HCO3- secretion) when compared with euthyroid animals. The hyperthyroid animals showed a decrease in Cl- mucosal to serosal transport. Furthermore, a significant correlation was found between serum L-thyroxine (T4) levels and both net Cl- transport (r = -0.74, P < 0.00001) and residual ion flux (r = -0.55, P < 0.005). These results indicate that the effect of T4 is firstly to inhibit Cl-/HCO3- anion exchange thereby influencing transepithelial flux transport and secondly to affect intestinal motility. Such inhibition was not found when T4 was acutely added to rat ileum, suggesting that the effect on electrolyte transport probably requires protein synthesis. In conclusion, the phenomenon observed in vitro could explain the clinical manifestations of constipation and diarrhoea in hypo- and hyper-thyroidism respectively.

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Discrepancy between the intestinal lactase enzymatic activity and mRNA accumulation in sucklings and adults Effect of starvation and thyroxine treatment

1989

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The accumulation profile of intestinal lactase mRNA was investigated in suckling and adult rats and pigs. We found no correlation between the lactase enzymatic activity and the accumulation of the messenger at both developmental stages. Modulation of lactase activity by starvation or thyroxine treatment had no effect on lactase mRNA accumulation in the rat intestine. These results confirm that thyroxine modulates lactase expression essentially at the post-transcriptional level.

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Modulation by Thyroxine of the Amount of Lactase Protein in the Jejunum of Adult Rats

Cited by 4 publications

References 13 publications

Dietary Sucrose Enhances Intestinal Lactase Gene Expression in Euthyroid Rats

Dietary Sucrose Enhances Intestinal Lactase Gene Expression in Euthyroid Rats

Thyroxine effect on intestinal Cl−/HCO3− exchange in hypo- and hyperthyroid rats

Discrepancy between the intestinal lactase enzymatic activity and mRNA accumulation in sucklings and adults Effect of starvation and thyroxine treatment

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