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Horm Behav. 2006 Jun;50(1):70-6. Epub 2006 Mar 9.

Reproductive experience alters anxiety-like behavior in the female rat.

Author information

1
Department of Biomedical Sciences, Tufts University, Cummings School of Veterinary Medicine, 200 Westboro Road, North Grafton, MA 01536, USA. elizabeth.byrnes@tufts.edu

Abstract

Reproductive experience (i.e. pregnancy and lactation) results in significant alterations in subsequent hormone levels in female rats. Several studies have demonstrated that circulating hormones can significantly affect anxiety-like behavior. Thus, the purpose of the present study was to determine whether reproductive experience induces alterations in anxiety-like behaviors in cycling female rats and in older, reproductively senescent rats. In Experiment 1, the elevated plus maze (EPM) was used to test young cycling (6-8 weeks post-weaning) and middle-aged (32-36 weeks post-weaning) primiparous rats and their age-matched nulliparous counterparts for anxiety-like responses. In Experiment 2, activity in the open field was used as an additional measure of anxiety-like behavior in young (proestrus) and middle-aged (constant estrus) primiparous and nulliparous rats. For Experiment 3, EPM testing was conducted in separate groups of young and middle-aged animals tested two weeks after ovariectomy. The results revealed that during proestrus, primiparous animals exhibited fewer anxiety-like behaviors on the EPM compared to nulliparous controls. In middle-aged animals, however, parity was associated with increased anxiety-like behavior. In the open field, young, non-lactating primiparous animals again exhibited fewer anxiety-like behaviors compared to nulliparous controls, an effect that was reversed in middle-aged animals. Effects of reproductive experience on the EPM in both age groups were eliminated by ovariectomy. Overall, the findings indicate that reproductive experience significantly alters anxiety-like behavior, effects that are influenced by the endocrine status and/or age of the female.

PMID:
16524576
DOI:
10.1016/j.yhbeh.2006.01.006
[Indexed for MEDLINE]

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