Developmental Profile of Access Induced Sucrose Consumption and Response to Access Change in Male Rats

The Intermittent Access Sweets (IAS) protocol shows enhanced consumption by adult rats when they are given once every third day access (E3DA) to 4% sucrose solution (Hewitt & Eikelboom, 2008). With this access protocol non-food-deprived E3DA rats consume ∼100% more sweet solution per day than rats with every day access (EDA).When all rats are switched to an equivalent alternate day access (E2DA) schedule the consumption difference is maintained and can last for more than 50 days. Experiment's 1 and 2 assess the IAS protocol consumption difference with older and younger rats respectively, testing if the effect is stable across the rat lifespan. Results from these developmental profile experiments show the IAS effect is evident across the rat lifespan although prior to puberty the consumption difference is not as pronounced. Experiment's 3 and 4 examine the longer-term consequences of access conditions (EDA, E3DA) typically used with the IAS protocol. Experiment 3 shows that a period of EDA to sucrose does not protect rats from immediately escalating intake when access is shifted to E3DA. Experiment 4 shows intermittent access (E3DA) may lead to robust enhanced consumption that is maintained for some time with a changed access schedule; when rats are shifted from E3DA to EDA it appears consumption declines slowly though the variance in sucrose consumption tempers this conclusion. These findings imply that access conditions are a factor in enhanced consumption patterns and this enhancement may be a key component in the development of addiction. Interestingly the access effect may not be as powerful pre-puberty, but becomes pronounced in adolescence, a time period associated with initiation of drug use and vulnerability to addiction.