Brain glycogen supercompensation after different conditions of induced hypoglycemia and sustained swimming in @entity5660 ( XXXX ).

@entity5660 @entity413
UNASSIGNED: Brain glycogen is depleted when used as an emergency energy substrate. In mammals, brain glycogen levels rebound to higher than normal levels after a hypoglycemic episode and a few hours after refeeding or administration of @entity413 . This phenomenon is called glycogen supercompensation. However, this mechanism has not been investigated in lower vertebrates. The aim of this study was therefore to determine whether brain glycogen supercompensation occurs in the @entity5660 brain. For this purpose, short-term brain @entity413 and glycogen contents were determined in @entity5660 after being subjected to the following experimental conditions: i) a 5-day or 10-day fasting period and refeeding; ii) a single injection of insulin (4mgkg(-1)) and refeeding; and iii) sustained swimming and injection of @entity413 (500mgkg(-1)). Food deprivation during the fasting periods and insulin administration both induced a decrease in @entity413 and glycogen levels in the brain. However, only refeeding after 10days of fasting significantly increased the brain glycogen content above control levels, in a clear short-term supercompensation response. Unlike in mammals, prolonged exercise did not alter brain @entity413 or glycogen levels. Furthermore, brain glycogen supercompensation was not observed after @entity413 administration in fish undergoing sustained swimming. To our knowledge, this is the first study providing direct experimental evidence for the existence of a short-term glycogen supercompensation response in a teleost brain, although the response was only detectable after prolonged fasting.
