Thyroid hormone effects on lactase expression by rat enterocytes.

Hewitt, J E; Smith, Michael W.

doi:10.1113/jphysiol.1986.sp016152

Cited by 12 publications

(18 citation statements)

References 33 publications

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“…In addition, the effect on LPH was specific, since no change was observed in the activity of ac-glucosidase (sucrase-isomaltase and maltase). This selectivity was not observed in adult rats fed ad libitum, since both LPH and sucrase activities increased 12 h after a single injection ofT3 or T4 (Hewitt & Smith, 1984 (Hewitt & Smith, 1984). …”

Section: Discussionmentioning

confidence: 97%

“…A dose 3-4 times this amount was therefore used in the present study. In addition, 150 nmol T3 kg-1 (0-1 ,ug T3 g-1) was the dose used in previous studies to investigate the effect of T3 on intestinal enzyme activity (Hewitt & Smith, 1986). Taking the potency of T3 to be 10 times as great as that of T4, the present dose is also equivalent to the 1 ,ug T4 g-1 used in earlier studies (Hewitt & Smith, 1986;.…”

Section: Methodsmentioning

confidence: 99%

“…In addition, 150 nmol T3 kg-1 (0-1 ,ug T3 g-1) was the dose used in previous studies to investigate the effect of T3 on intestinal enzyme activity (Hewitt & Smith, 1986). Taking the potency of T3 to be 10 times as great as that of T4, the present dose is also equivalent to the 1 ,ug T4 g-1 used in earlier studies (Hewitt & Smith, 1986;. A maintenance dose (43-9 nmol T3 kg-1 at each subsequent time period) was provided at 30 min intervals, at a rate equivalent to that calculated to be cleared from the system, with the halflife of T3 in the young pig being taken as 1 h (Dauncey & Ingram, 1986a).…”

Section: Methodsmentioning

confidence: 99%

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Administration of 3,5,3'‐triiodothyronine induces a rapid increase in enterocyte lactase‐phlorizin hydrolase activity of young pigs on a low energy intake

Tivey¹,

Morovat²,

Dauncey³

1993

Experimental Physiology

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SUMMARYThe rapid increase in plasma concentration of 3,5,3'-triiodothyronine (T3) which occurs after feeding may invoke changes in lactase-phlorizin hydrolase (LPH) activity of the small intestine. This hypothesis has been tested in 6-week-old pigs living at thermal neutrality (26°C) on a low level of energy intake. Littermate pairs were infused with either saline or T3 at 30 min intervals over a 6 h period, 18-24 h after the last meal. The activity of LPH in mucosal homogenates increased significantly in test compared with control animals (P < 0 05; T3 37 % > saline). This was a specific effect on LPH since there was no effect of T3 on the activity of sucrase-isomaltase. Further, it could not be attributed to changes in intestinal morphology since there were no differences in crypt depth, villus height or villus area between the two groups. Enzymecytochemical analysis indicated that administration of T3 increases LPH activity at all points along the villus axis, whereas there is no effect on a-glucosidase (combined sucrase-isomaltase and maltase) activities. These results indicate that there is unlikely to be a simple causal relation between the immediate increase in plasma T3 after feeding and the initial decline in LPH activity observed previously in young pigs living in a cold environment. By contrast, the subsequent increase in LPH activity could be under the direct control of the food-induced increase in plasma T3 concentration, and the present results suggest a potential role for T3 as an important short-term homeostatic regulator of LPH in the small intestine.

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Section: Discussionmentioning

confidence: 97%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Administration of 3,5,3'‐triiodothyronine induces a rapid increase in enterocyte lactase‐phlorizin hydrolase activity of young pigs on a low energy intake

Tivey¹,

Morovat²,

Dauncey³

1993

Experimental Physiology

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“…In a study of the influence of T4 on lactase expression in adult rats, Hewitt & Smith (1984) found that although the hormone caused a decrease in lactase after 48 h, it resulted in an increase after only 8 h. This increase in enzyme activity was particularly marked in enterocytes which had already moved up the villus and were therefore older. Young pigs kept in the cold maintain enterocytes on the villus for about 5000 more time than their litter-mates in the warm (Dauncey, Ingram, James & Smith, 1983).…”

Section: Discussionmentioning

confidence: 99%

Alteration of Lactase and Aminopeptidase N Expression in Porcine Enterocytes by Energy Intake and Environment

Dauncey

Ingram

1986

Exp Physiol

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SUMMARYThe influence of nutrition, environmental temperature and time of feeding on lactase and aminopeptidase N activities in enterocytes of young pigs has been investigated. Animals were kept in the cold (10°C) or warm (35°C) and given either a high or low energy intake. In animals from the cold, lactase activity as determined by scanning microdensitometry was significantly lower at 4 h after a meal than it was in animals from the warm. At 6 h, the activities were similar in all groups, while at 20-24 h after feeding, lactase activity was much greater in those kept at 10°C than in those at 35 'C. Level of energy intake had no statistically significant effect and no differences were found with respect to aminopeptidase N. The possibility that these differences in lactase activity are related to thyroid hormone metabolism and energy supply in relation to demand is discussed.

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“…Frozen jejunal sections prepared from suckling (15-day-old) and post-weaning rats (23 days old, Tsuboi et al 1985;46 days old, Jonas et al 1985) were incubated under initial rate conditions with 5-bromo-4-chloro-3-indolyl fl-D-glucopyranoside as substrate for lactase, the amount of substrate hydrolysed then being determined using a Vickers M84 scanning microdensitometer (Hewitt & Smith, 1986). Enterocyte migration rates determined in these same animals by [3H]thymidine injection were 2-6+004 for 15-day-old.and 11-7+009 mh-1 for 23-plus 46-day-old rats (means+s.E.M.…”

Section: Pmentioning

confidence: 99%

Proceedings of the Physiological Society, 18‐19 September 1987, Cambridge Meeting: Communications

1988

The Journal of Physiology

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M13 9PTInteractions have been described between glucose metabolism and gastric function. For example, Davenport (1950) first reported that increased glucose concentration in stomach perfusate caused an increase in gastric acid secretion. Conversely, gastrin affects glucose metabolism (Unger, Ketterer, Duprez & Eisentraut, 1967;Hansky, Soveny & Korman, 1973;Ibu, Amure & Watson, 1975;Ibu, 1985). However, the effects of the hyperglyeaemia of diabetes mellitus on gastric acid secretion have not yet been elucidated.Male Sprague-Dawley albino rats (250-300 g) were made diabetic by a single intraperitoneal (i.P.) injection of 60 mg kg-' body weight streptozotocin (STZ) freshly prepared in citrate buffer. Control rats were injected with citrate buffer alone. Diabetes was detected 24 h after STZ injection by glycosuria and confirmed by raised plasma glucose 2 weeks after STZ injection. On this day the rats were anaesthetized with 110 mg kg-1 body weight Inactin injected i.P. and surgically prepared for stomach perfusion by the modified method of Ghosh & Schild (1958). Normal saline (0-9 % NaCl) was infused at 75 ,I min-' for 30 min followed by randomized 1 h infusion periods of pentagastrin (Sigma) either 0 4 ,jg, 0-8 jug or 1 6 ,ug h-1 100 gb ody weight, with 30 min control collections between the doses. Gastric effluent samples were collected in 10 min aliquots and titrated to a phenolphthalein endpoint.Plasma glucose levels (mM) were 5-6 + 0-5 and 33.9 + 3.5 for control and diabetic rats respectively. Basal acid output (mM h-1) was lower in diabetic rats (1I0+0-05) than in control rats (1-36+0-06). However, pentagastrin evoked a greater secretory effect (mM h-') in the diabetic rats (2-79 + 0-26, 3-89 + 0 45, 6-99 + 0-36 at the three doses of pentagastrin used as compared with 2-02 + 0 13, 2-41 + 0-18 and 3.77 + 0 33 in the control rats), P < 0-01, n = 6, paired t test.It is inferred that the lower basal acid output in STZ diabetic rats may be due to the chronic hyperglycaemic state, but that the sensitivity of these diabetic rats to pentagastrin is enhanced.

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Thyroid hormone effects on lactase expression by rat enterocytes.

Cited by 12 publications

References 33 publications

Administration of 3,5,3'‐triiodothyronine induces a rapid increase in enterocyte lactase‐phlorizin hydrolase activity of young pigs on a low energy intake

Administration of 3,5,3'‐triiodothyronine induces a rapid increase in enterocyte lactase‐phlorizin hydrolase activity of young pigs on a low energy intake

Alteration of Lactase and Aminopeptidase N Expression in Porcine Enterocytes by Energy Intake and Environment

Proceedings of the Physiological Society, 18‐19 September 1987, Cambridge Meeting: Communications

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