Effects of chronic restraint stress and estradiol on open field activity, spatial memory, and monoaminergic neurotransmitters in ovariectomized rats
Section snippets
Subjects
Thirty-two female Sprague–Dawley rats (Harlan Sprague–Dawley, Indianapolis, IN, USA) aged 55–60 days old (upon arrival) served as subjects. All animals were maintained on a 14/10-h light/dark cycle (lights on at 05:00 h) and in accordance with the NIH Guide for Care and Use of Animals. Animals were allowed to acclimate to the housing environment for two weeks. During the acclimation period and the 21-day stress period, all subjects were double housed in plastic tubs. All animals were weighed
Weight
Animal weight gain was affected by stress (F1,92=16.72, P<0.0001), estradiol (F1,92=188.40, P<0.0001), and time (F1,92=34.98, P<0.0001). Weight gain across the daily restraint period was also influenced by the stress×time interaction (F4,92=2.88, P<0.03) and the estradiol×time interaction (F4,92=9.23, P<0.0001). As seen in Fig. 1, stressed animals weighed less than the non-stress and estradiol-treated females weighed less than their cholesterol controls across the stress period.
Open field
Open field
Body weight
All animals used in this study gained weight across time; however, the weight gain differed among the treatment groups. Stressed females gained less weight than non-stress females across the 21 days and this is consistent with previous studies in which both stress and CORT administration led to decreases in body weight (McLay et al., 1998, Beck and Luine, 1999, Akana et al., 1999, Bowman et al., 2001). Additionally, all estradiol-treated females weighed less than their cholesterol counterparts,
Acknowledgements
Financial support for this work was provided by NRSA 1F31MH12515 to R.E.B. and Hunter College MARC, RISE, and RCMI grants (NIGMS). We extend our appreciation to Dr. Sosimo Fabian for critical review of the manuscript and Dr. Mark Zrull for statistical consultation.
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