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Development of glucose active transport in embryonic chick intestine. Influence of thyroxine and hydrocortisone
1Department of Zoology, North Carolina State University, Raleigh 27695-7617.
Insights
Embryonic chick duodenum exhibits glucose active transport, which significantly increases post-hatching. Hormones like thyroxine and hydrocortisone enhance this transport via distinct mechanisms.
Area of Science:
- Developmental biology
- Endocrinology
- Gastrointestinal physiology
Background:
- Glucose active transport is crucial for nutrient absorption in the developing gut.
- The embryonic chick duodenum is a model for studying intestinal development.
- Hormonal regulation of intestinal transport mechanisms is not fully understood.
Purpose of the Study:
- To investigate the developmental profile of glucose active transport in embryonic chick duodenum.
- To determine the effects of thyroxine and hydrocortisone on glucose active transport in vitro.
- To elucidate the distinct mechanisms by which these hormones influence glucose transport.
Main Methods:
- Measurement of glucose active transport in embryonic and post-hatch chick duodenal tissues.
- In vitro culture of embryonic duodenum with hormonal treatments.
- Analysis of hormonal mechanisms including protein synthesis and calcium modulation.
Main Results:
- Glucose active transport is present in 12-day embryonic chick duodenum and increases 11-fold postnatally.
- In vitro cultures of 14-day embryonic duodenum achieve in vivo rates of glucose transport.
- Thyroxine and hydrocortisone significantly increase glucose active transport in vitro, acting through different pathways.
Conclusions:
- Glucose active transport in the chick duodenum develops significantly during late embryonic and early postnatal stages.
- Thyroxine and hydrocortisone are potent enhancers of glucose active transport, suggesting critical roles in intestinal maturation.
- The distinct mechanisms of action for thyroxine and hydrocortisone highlight complex hormonal regulation of nutrient transport.
Abstract:
1. Glucose active transport is detectable in 12-day-old embryonic chick duodenum and increases at least 11-fold after 4 days of postnatal life. 2. Glucose active transport develops at the in vivo rate in 72-hr cultures of 14-day embryonic duodenum. 3. In the presence of either 1 nM thyroxine or 1 microM hydrocortisone in vitro, glucose active transport reaches levels approximately 200% of control values (equivalent to 18-19 day levels in vivo). 4. Thyroxine and hydrocortisone act by different mechanisms based on their antagonistic interaction and differences in time course of action, requirement for protein synthesis and modulation by extracellular calcium.