The Effects of Estradiol and Exercise on Brain-Derived Neurotrophic Factor Levels in Untrained, Naïve Female Rats
Estradiol treatment and exercise cause alterations in the brain and cognition. As women approach menopause, cognitive ability often changes, a modification seen most robustly as a decline in verbal declarative memory. To combat this deficiency, estrogen replacement therapy (ERT) is often administered. However, due to inconsistent research findings, the effects of ERT are largely unknown. Thus, an alternative or supplement to ERT is needed. Exercise may serve as an appropriate complement to ERT, as exercise as been shown to increase brain-derived neurotrophic factor (BDNF) protein levels in the brain. This study investigated the effects of estradiol and exercise on BDNF protein levels in rats in the hippocampus, frontal cortex, olfactory bulb, cerebellum, and striatum. BDNF protein levels were analyzed with an enzyme-linked immunosorbent assay (ELISA). In addition, the corticosterone (CORT) levels of young and middle-aged rats were analyzed with an ELISA as well. It was shown that in some areas of the brain, estradiol and exercise actually inhibited BDNF production, while in other brain regions, exercise and estradiol stimulated BDNF synthesis. Also, analysis of CORT levels showed that exercise tended to increase CORT levels and estradiol lowered CORT levels in young rats. In middle-aged rats, a significant difference in CORT levels due to estradiol and exercise was not observed. The decrease in BDNF levels seen in the hippocampus may be due to an increase in CORT levels, as CORT is known to inhibit BDNF production. Consequently, more research is needed to identify exercise as a useful supplement to ERT.
School:
University of Illinois at Urbana-Champaign
Department:
Molecular and Cellular Biology
Research Advisor:
Donna Korol
Department of Research Advisor:
Psychology
Year of Publication:
2007