Proactive influence of a surgical stressor on locomotor activity, exploration and anxiety-related behaviour following acute footshock in the mouse

The putative proactive influence of graded surgical stressors including int raventricular cannulation, sham surgery and no surgery on footshock-associa ted variations of locomotor activity, rearing and anxiogenic behaviour in t he light-dark paradigm was evaluated among CD-1 mice. Neither sham surgery nor cannulation of the lateral ventricle altered baseline measures of locom otor activity or rearing relative to the performance of nonoperated control animals. Cannulation exacerbated the depressant influence of acute footsho ck on locomotor activity, while sham surgery mitigated the disruptive effec t of the stressor on locomotor activity during the initial 15-min period of the test session. Footshock suppressed the vertical activity scores of mic e regardless of surgical history. Only intraventricular cannulation reduced the baseline time in light scores of mice in the light-dark paradigm with repeated testing relative to animals in the sham surgery and no-surgery con ditions. Baseline transition scores were not differentially affected by sur gical history. Typically, transition scores were reduced on day 2 relative to day 1, but additional performance decrements were precluded on day 3. Fo otshock interacted with the surgical stressor of intraventricular cannulati on in exaggerating reduced time in light relative to the performance of mic e in the remaining surgical conditions. Transition frequency was not differ entially influenced by the nature of the surgical stressor and subsequent e xposure to footshock. The implications of these data for stressor-induced p athology are discussed. (C) 1999 Elsevier Science Inc.