AJP - Regulatory, Integrative and Comparative Physiology, Vol 267, Issue 2 612-R615, Copyright © 1994 by American Physiological Society
L-ethionine, an amino acid analogue, stimulates eating in rats
N. E. Rawson, P. M. Ulrich and M. I. Friedman
Monell Chemical Senses Center, Philadelphia, Pennsylvania 19104.
The fructose analogue 2,5-anhydro-D-mannitol (2,5-AM) triggers feeding in
rats through its actions in liver, which include a decrease in ATP due to
trapping of phosphate. To determine whether decreasing liver ATP by a
different means would also trigger feeding, we gave rats L-ethionine (ETH),
an amino acid analogue that reduces ATP in liver by trapping adenosine as
S-adenosyl-L-ethionine. ETH-treatment increased food intake from 4 to 8 h
after administration, without affecting 24-h intake. Two hours after
treatment, liver ATP was 25% lower in rats given ETH than in
vehicle-treated controls. Circulating fuels and liver lactate and pyruvate
were not affected by ETH treatment, whereas liver glycogen was 15% lower in
ETH-treated rats. These results are the first to show that an amino acid
analogue elicits feeding in rats fed protein-sufficient diets. Because a
decrease in liver ATP is the only common effect of ETH and 2,5-AM observed
thus far, a signal related to liver ATP status may be involved in the
mechanism for initiation of feeding in rats.
