Effects of reversed light-dark cycles on physical parameters of pregnant rats

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  • 明暗サイクルの変化が母胎に及ぼす影響

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Abstract

The purpose of this study was to investigate the effects of changes in daily light-dark cycles on physical parameters, hormone secretion and embryo growth in pregnant rats.<BR>Forty-three 8 weeks old female Wistar rats were randomly divided into four groups; non-pregnant control group (n=10), pregnant control group (n=10), non-pregnant shift group (n=12), and pregnant shift group (n=11) . The control group bred in daily common light-dark cycle (light period 9: 00-21: 00, dark period 21: 00-9: 00) . The shift group bred in shifting of daily reversed light-dark cycle (light period 21: 00-9: 00, dark period 9: 00-21: 00) and common cycle. The common cycle was set in the first day (day 0), and the reversed cycle was set in the second day (day 1) . And then the common cycle was set in the third day (day 2), and similarly, shifting of the cycles was repeated in the following days.<BR>The blood sugar in the pregnant shift group was higher than in the other groups. On the contrary, the body weight of embryo in the shift group was less than that of the control group. Furthermore, although corticosterone concentration showed no difference between shift and control groups, noradrenaline concentration of the shift group tended to be higher than those of the control group.<BR>We conclude that growth retardation of embryos may result from increased noradrenaline secretion. It is strongly suggested that the reversed light-dark cycle acts as the stressor especially for pregnant mothers.

Journal

  • Structure and Function

    Structure and Function 5 (1), 9-16, 2006

    Co-medical Research Society of Structure and Function

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