Abstract
To study the ontogenic change in stress susceptibility during postnatal brain development, we have previously examined the ontogenic changes of Fos expression in the paraventricular nucleus of the hypothalamus (PVN) after intraperitoneal (i.p.) injection of cinchophen. We have obtained evidence that Fos was induced by cinchophen in PVN after postnatal day (P)10. Such differential responses to stress have led us hypothesize that such stressful stimuli at various time point during postnatal development may differentially affect motor behavior in adult rat. To test this hypothesis, we applied an open field test and a rotarod test using rats that received i.p. injection of cinchophen on P5, P7, P10 and P15. There were no significant differences of body weight and muscle strength between them. In open field test, female rats that received cinchophen injection on P10 tended to stay longer in the center of the field at P30, suggesting that they showed anxiety to a novel environment. In rotarod test, there was no significant difference among all groups. These results indicate that postnatal stress by cinchophen may affect in part their motor behavior related to anxiety in adult rat. [J Physiol Sci. 2006;56 Suppl:S98]
