Nicotine does not produce state-dependent effects on learning in a Pavlovian appetitive goal-tracking task with rats

摘要

Past research has shown that when rats received 0.4 mg base/kg nicotine paired reliably with intermittent sucrose delivery that anticipatory sucrose-seeking behavior (i.e., goal tracking) was differentially displayed in the nicotine state relative to intermixed saline sessions in which no sucrose was delivered. The present research extended this observation to a lower dose of nicotine (i.e., 0.2 mg base/kg) and tested a state-dependent learning account of differential conditioned responding. According to this account, the increase in goal tracking on nicotine sessions reflects a chamber-sucrose association that is only recalled when in the nicotine state. We used a 2 × 2 factorial design in which rats received sucrose deliveries in one drug state (nicotine or saline) and were then tested in the same state (Nic→Nic or Sal→Sal) or a different state (Nic→Sal or Sal→Nic) after acquiring the conditioned response. A state-dependency account predicts disruption in conditioned goal tracking for rats that receive a shift in drug state on the test day. This disruption did not occur suggesting that differential control of conditioned responding by nicotine is more likely due to a direct excitatory association between the interoceptive cueing effects of nicotine and the appetitive qualities of sucrose.