Presence of escalation effect in short access and long access exposure to non-drug reinforcer

Ahmed and Koob (1998) demonstrated an increase in self-administration of cocaine during long-term exposure as opposed to short-term exposure. This increase is described as an increase in the hedonic set point which dictates the amount of drug needed to have an effect. One argument against this increase appearing as a result purely of increase in hedonic set point, is that the increase seen is due to a habituation to negative effects of cocaine. The study presented here attempted support this theory of habituation using an analogous non-drug reinforcer. Water restricted rats were given short-access or long-access to quinine water similar to that of Ahmed and Koob (1998). Total water consumption was used as measurement of habituation. Results show that short-access actually produced an effect similar to escalation rather than long-access. Habituation occurred quickly for long-access rat resulting in a non-significant increase. Short-access allowed for gradual habituation over time.