Pattern of daily water consumption in relation to intake of saccharin solution
Twelve nondeprived rats were presented with a bottle (B2) containing.25% saccharin solution for 1 h each day in addition to the maintenance water bottle (Bl). After 18 days (preshift), the contents of B2 were changed to plain tap water for 6 days (postshift). Intake from B1 in the 2 h preceding the time of B2 presentation increases during preshift while overnight intake decreased, suggesting the emergence of a B1 drinking schedule as intake from B2 increased. However, detailed aspects of the results were not consonant with this possibility. During postshift, intake from B1 returned to the initial preshift level while intake from B2 settled at a much higher level, suggesting the operation of secondary reinforcement.
Effects of periodic withdrawal on ethanol and saccharin selection in rats
Abstract When rats with continuous access to water are given periodic access to ethanol solutions, selection of the ethanol solutions is considerably higher than if the solutions of ethanol are continuously available. In Experiment 1 the same effect was demonstrated with solutions of sodium saccharin, thus showing that the basis of the effect is not related to the particular metabolic, intoxicating, or addictive properties of ethanol. In Experiment 2 the effects of periodic withdrawal on the selection of ethanol and sodium saccharin solutions were directly compared and several manipulations of the schedule of availability had the same effect in both the ethanol and sodium saccharin conditions. The results of Experiments 2 indicated that the basis for the facilitatory effects of periodic withdrawal on the selection of sapid solutions is a taste-related inhibitory factor which develops with consumption of a flavored substance and dissipates over periods when the substance is not consumed. Thus, selection is greater under conditions of periodic availability because of the lack of inhibition. This working hypothesis can not only account for the effects of periodic withdrawal but is also applicable to the alcohol-deprivation effect and the saccharin-elation effect, 2 phenomena which appear to be specific instances of the effects of periodic availability.
Altered nociception and morphine tolerance in neuropeptide FF receptor type 2 over‐expressing mice
The neuropeptide FF system is thought to act as an anti‐opioid modulator and plays a role in nociception, morphine antinociception and dependence. Two receptor subtypes, NPFFR1 and NPFFR2, have been identified, but their respective roles in these processes remain uncertain.