| dc.description.abstract | The importance of cannabinoid receptors has risen in recent years due to the increasing number of states that have legalized marijuana. Previous research from our lab has explored coping with multiple instances of reward loss when exposed to large, chronic doses of the cannabinoid agonist WIN 55, 212-2 (WIN, 10 mg/kg). When chronically exposed rats received a consummatory successive negative contrast (cSNC) downshift from 32% to 4% sucrose, they were less able to cope with the subsequent autoshaping downshift of 12 pellets to 2 pellets. Additional autoshaping research from our lab has shown multiple downshifts in autoshaping to be successful in obtaining contrast effects. The present research combined this procedure with occasional acute doses of WIN (1 mg/kg) to determine if only one kind of downshift experience, autoshaping, was sufficient to produce less coping efficacy if repeated. Rats were randomly assigned to either WIN or vehicle control groups, and then trained in acquisition with discrete lever presentations where one lever was always followed by the delivery of 12 pellets, and a second lever was always followed by 2 pellets. After acquisition, rats received downshift sessions once per week, wherein the lever previously associated with 12 pellets was downshifted to 2 pellets. Prior to each of 4 downshift sessions, rats received intraperitoneal injections of either WIN or vehicle solution. Lever presses to each lever during discrete "forced choice" and simultaneous "free choice" trials, and head entries into the cup where food was delivered, or "goal entries," were both recorded to assess preference and explore downshift effects. Although acute WIN administration did not affect lever preference relative to vehicle controls, it did result in decreased lever pressing in favor of goal tracking during the downshift. Therefore, WIN seems to encourage rats to be more focused on the outcome instead of responding to signals for the outcome, which may have implications for reducing impulsive behavior despite extensive training. | |
