Nutritional and environmental factors affecting plasma ghrelin and leptin levels in rats.
We examined which factors suppress the rise of ghrelin secretion under hunger in 16-h-starved rats, and compared the responses of plasma ghrelin and leptin levels to various exogenous and endogenous stimuli in intact rats. Although an acute expansion of the stomach by infusion of 6 ml air or 3 ml water in rats starved for 16 h did not change the level of plasma acyl-ghrelin 3 ml corn starch solution, corn oil, or 20% ethanol significantly decreased it. Vagotomy inhibited suppression by nutrients but not by ethanol. Chronic infusion of ethanol into the stomach for 3 weeks in free-feeding rats caused widespread injury of the stomach mucosa, and increased both plasma ghrelin levels and the number of ghrelin cells. In intact rats, low temperature did not change ghrelin levels, but increased leptin levels. On the other hand, restriction stress decreased plasma ghrelin levels, but had the reverse effect on plasma leptin levels. Although insulin decreased and 20% glucose increased plasma glucose levels, they both decreased plasma ghrelin levels. Insulin elevated plasma leptin levels, but glucose had no effect. These results indicate that 1) acyl-ghrelin secretion from the stomach under fasting condition is suppressed by nutrients but not by mechanical expansion of the stomach; 2) high and low environmental temperature, stress, or administration of insulin reciprocally affect plasma levels of ghrelin and leptin; and 3) an increase of stomach ghrelin cell number and plasma ghrelin levels after chronic ethanol treatment may be involved in restoration of gastric mucosae.
Nakahara
Keiko
K
Department of Veterinary Physiology, Faculty of Agriculture, University of Miyazaki, Miyazaki, Japan.
Okame
Rieko
R
Katayama
Tetsuro
T
Miyazato
Mikiya
M
Kangawa
Kenji
K
Murakami
Noboru
N
D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D004777:Environment; D000431:Ethanol / Q000633:toxicity; D005753:Gastric Mucosa / Q000187:drug effects / Q000293:injuries / Q000502:physiology; D054439:Ghrelin / Q000097:blood* / Q000378:metabolism; D007328:Insulin / Q000097:blood; D020738:Leptin / Q000097:blood*; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D013217:Starvation / Q000097:blood; D014628:Vagotomy; D014630:Vagus Nerve / Q000502:physiology
D001786:Blood Glucose; D054439:Ghrelin; D007328:Insulin; D020738:Leptin; D000431:Ethanol