Abstract
Reactivity to novelty has been related to operant drug self-administration but does not seem involved in the conditioned place preference (CPP). To further assess this issue our aims were to investigate: (1) the importance of the initial versus delayed activity in the novel environment to predict the CPP induced by morphine; (2) the separate contribution of trait anxiety in morphine CPP. Male Sprague-Dawley rats were exposed to a circular corridor for 30 min to assess reactivity to novelty and to the elevated plus-maze and the light-dark tests as measures of anxiety and morphine CPP was then studied (three pairings with 5 mg/kg s.c. morphine and three with saline). Delayed activity in the corridor (16-30 min) correlated positively with CPP score, whereas the initial activity (0-15 min) did not. High-responders (HR), those more active during the second half of the corridor, developed morphine CPP in contrast to low-responders (LR). Also, HR and LR did not differ in anxiety nor any plus-maze or light-dark test measure correlated with CPP behaviour. Enhanced vulnerability to develop morphine CPP is predicted by a higher delayed activity in a novel environment, regardless of anxiety. © 2005 Elsevier B.V. All rights reserved.
Original language | English |
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Pages (from-to) | 72-79 |
Journal | Behavioural Brain Research |
Volume | 165 |
Issue number | 1 |
DOIs | |
Publication status | Published - 30 Nov 2005 |
Keywords
- Addiction
- Anxiety
- Individual differences
- Locomotor activity
- Place conditioning
- Response to novelty
- Reward