Changes in ghrelin, CCK, GLP-1, and peroxisome proliferator-activated receptors in a hypoxia-induced anorexia rat model

Abstract

Introduction: 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 timedependent changes occurring in plasma gut hormones, PPARα, PPARδ, and PGC1α, in the stomach and liver during hypoxia.

Material and 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.

Conclusion: 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. (Endokrynol Pol 2015; 66 (4): 334–341)