Abstract

The search for the control of feeding behavior has long been an object of intensive study. While some researchers have focused on neural control possibilities, others have studied the possible chemical basis behind feeding mechanismsr and still other researchers have combined ideas from both of these areas. One such mechanism might be the levels of reserve adenosine-s-triphosphate (ATP) in body tissues. Perhaps animals might increase their food intake when ATP stores decrease and decrease their intake when ATP stores increase. Evidence from experiments on adult rats indicate that this hypothesis has merit. In this study, we investigated this possible cue for ingestive-behavior control by preweanling rats.

We studied 20- and 12-day-old rat pups using two chemicals, 2,5-anhydro-D-mannitol (AM) (a fructose analogue) and L-ethionine (LE). Administration of AM and LE in adult rats decreases hepatic ATP levels and increases food intake. AM also decreases blood glucose levels. AM accomplishes this by sequestering free phosphate within the system while LE sequesters free adenosine within the system to lower ATP levels. Since these results occur with AM and LE treatment in adult rats, it is possible that AM and LE treatment might have similar effects in rat pups. In our studies on 20- and 12-day-old rat pups, we measured the blood glucose levels one hour after injection and measured the amount of food intake at 60 and 120 minutes after injection.

AM iniections decreased blood glucose levels significantly as the concentration of AM injections increased. However, rather than increasing food intake, AM injections had no significant effect on feeding. Furthermore, LE injections had no significant effect on either blood glucose or feeding in 20-day-old pups. These results indicate that either ATP stores have no effect on ingestion in preweanling rats or that pups do not respond to AM and LE in the same manner as adults. These alternatives are being investigated in further studies on changes in ATP stores.