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Mood and memory function in ovariectomised rats exposed to social instability stress
Badriya Al-Rahbi1, Rahimah Zakaria, Zahiruddin Othman
1Department of Physiology, School of Medical Sciences, Universiti Sains Malaysia, 16150 Kubang Kerian, Kelantan, Malaysia.
Biomed Research International
|July 11, 2013
Summary
Social instability stress impairs memory and mood in ovariectomized (OVX) rats by increasing corticosterone and decreasing estradiol. These effects were not observed in sham-operated controls, highlighting the role of ovarian hormones.
Area of Science:
- Neuroscience
- Endocrinology
- Behavioral Science
Background:
- Ovariectomy (OVX) in female rats leads to decreased estradiol levels.
- Social instability stress is a known model for inducing anxiety and depressive-like behaviors.
- The interplay between stress hormones and ovarian hormones in modulating cognitive and affective functions requires further investigation.
Purpose of the Study:
- To compare the impact of social instability stress on memory, anxiety- and depressive-like behaviors in sham-operated control rats versus ovariectomized (OVX) rats.
- To investigate the hormonal correlates, including estradiol, ACTH, and corticosterone, associated with stress responses in both groups.
Main Methods:
- Forty adult female Sprague-Dawley rats were divided into four groups: non-stressed sham-operated controls, stressed sham-operated controls, non-stressed OVX rats, and stressed OVX rats.
- Rats were subjected to a 15-day social instability stress protocol.
- Behavioral tests (novel object recognition, open field, forced swim) and serum hormone level measurements (estradiol, ACTH, corticosterone) were performed.
Main Results:
- OVX rats exhibited lower serum estradiol and uterine weight, and higher weight gain compared to sham-operated controls.
- Stressed rats showed significantly higher serum ACTH and corticosterone levels than non-stressed rats.
- Stressed OVX rats displayed significant memory deficits and increased anxiety- and depressive-like behaviors, unlike stressed sham-operated controls.
Conclusions:
- Ovariectomy exacerbates the negative effects of social instability stress on memory and mood.
- Elevated circulating corticosterone acts synergistically with low circulating estradiol to impair cognitive and affective functions.
- These findings underscore the critical role of estradiol in mitigating stress-induced behavioral and cognitive deficits.
