Changes in ghrelin, CCK, GLP-1, and peroxisome proliferator-activated receptors in a hypoxia-induced anorexia rat model.
BACKGROUND
A high-altitude environment causes appetite loss in unacclimatised humans, leading to weight reduction. Ghrelin, cholecystokinin (CCK), and glucagon like peptide-1 (GLP-1), are gut hormones involved in the regulation of food intake and energy metabolism. The liver is an important site of metabolic regulation, and together with the gut it plays a role in food intake regulation. This study intends to study the time-dependent changes occurring in plasma gut hormones, PPARα, PPARδ, and PGC1α, in the stomach and liver during hypoxia.


METHODS
Male Sprague Dawley rats were exposed to hypobaric hypoxia in a decompression chamber at 7620 m for different durations up to seven days.


RESULTS
Hypoxia increased circulating ghrelin from the third day onwards while CCK and GLP-1 decreased immediately. An increase in ghrelin, ghrelin receptor protein levels, and GOAT mRNA levels in the stomach was observed. Stomach cholecystokinin receptor (CCKAR), PPARα, and PPARδ decreased. Liver CCKAR decreased during the first day of hypoxia and returned to normal levels from the third day onwards. PPARα and PGC1α expression increased while PPARδ protein levels reduced in the liver on third day.


CONCLUSIONS
Hypoxia alters the expression of ghrelin and ghrelin receptor in the stomach, CCKAR in the liver, and PPAR and its cofactors, which might be possible role players in the contribution of gut and liver to anorexia at high altitude.
Arul Joseph
AJ
Duraisamy
Susovan
S
Bayen
Supriya
S
Saini
Alpesh Kumar
AK
Sharma
Endocrinology & Metabolism Division, Defence Institute of Physiology and Allied Sciences, Lucknow Road, Timarpur, Delhi - 110054, India. vatsp2001@rediffmail.com.
Praveen
P
Vats
Shashi Bala
SB
Singh
D000818:Animals; D000855:Anorexia / Q000209:etiology* / Q000378:metabolism; D002766:Cholecystokinin / Q000032:analysis / Q000235:genetics*; D004195:Disease Models, Animal; D005753:Gastric Mucosa / Q000378:metabolism; D005786:Gene Expression Regulation; D054439:Ghrelin / Q000032:analysis / Q000235:genetics*; D052216:Glucagon-Like Peptide 1 / Q000032:analysis / Q000235:genetics*; D000860:Hypoxia / Q000150:complications* / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D008297:Male; D047492:Peroxisome Proliferator-Activated Receptors / Q000032:analysis / Q000235:genetics*; D051381:Rats; D017207:Rats, Sprague-Dawley
D054439:Ghrelin; D047492:Peroxisome Proliferator-Activated Receptors; D052216:Glucagon-Like Peptide 1; D002766:Cholecystokinin