Regulation of endothelin-1 expression and function by nutrient stress in mouse colon epithelia.
OBJECTIVE
The endothelin (ET) system is influenced by a variety of stress conditions in many tissues. However, the effects of nutrient stress conditions on ET expression and its function are not well understood in the intestinal tract, while ET-1 gene expression and peptide were found in the intestinal tract. The aim of this study was to investigate the effect of feeding and fasting on the expression of ET-1 and short-circuit current (Isc) induced by ET-1 in mouse colon.


METHODS
Mice were fed freely, fasted for 48 h, and re-fed after fasting, respectively. ET-1 mRNA levels and peptide concentrations were analyzed using real-time polymerase chain reaction (PCR) and sandwich ELISA, respectively. Isc of epithelial tissue was measured under short-circuit conditions using a Ussing chamber.


RESULTS
ET-1 mRNA expression and peptide concentrations in epithelial colonic tissue were significantly increased 48 h after fasting, and decreased within 2 h of re-feeding after a 48-h fast. Furthermore, the addition of ET-1 to the serosal but not the mucosal side increased Isc in colonic epithelia. An increase in Isc was caused by chloride ion (Cl(-)) secretion because Isc induced by ET-1 was blocked by bumetanide and Cl(- -) free conditions. In addition, an increase in Isc induced by ET-1 in colon excised from fasted mice was much lower than that obtained from free-fed mice.


CONCLUSIONS
Gene expression, peptide concentration, and the function of ET-1 in mouse colonic epithelia are regulated by nutrient stress.
Kozakai
Takaharu
T
National Institute of Advanced Industrial Science and Technology (AIST), Institute for Biological Resources and Functions, Ibaraki, Japan.
Sakate
Mitsue
M
Saida
Kaname
K
D000818:Animals; D002034:Bumetanide / Q000494:pharmacology; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors; D002712:Chlorides / Q000037:antagonists & inhibitors / Q000378:metabolism; D003106:Colon / Q000378:metabolism* / Q000502:physiology; D004594:Electrophysiology; D019332:Endothelin-1 / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004848:Epithelium / Q000378:metabolism; D005215:Fasting; D005786:Gene Expression Regulation; D007413:Intestinal Mucosa / Q000378:metabolism* / Q000502:physiology; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D009130:Muscle, Smooth / Q000378:metabolism; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000378:metabolism; D013312:Stress, Physiological / Q000378:metabolism*; D019284:Thapsigargin / Q000494:pharmacology
D002712:Chlorides; D019332:Endothelin-1; D004791:Enzyme Inhibitors; D012333:RNA, Messenger; D002034:Bumetanide; D019284:Thapsigargin; D000252:Calcium-Transporting ATPases