Direct Intra-Accumbens 17 Beta-Estradiol Administration Increases Voluntary Wheel Running in Ovariectomized Rats

Metabolic dysfunction and the associated diseases (e.g., diabetes) are globally on the rise, and a sedentary lifestyle directly contributes to this issue. In fact, postmenopausal women are at increased risk for obesity and metabolic disease due to the loss of metabolically protective 17β-estradiol (E2). Exercise is vital for overall health, greatly reducing disease risk, but the central brain regions involved in drive for physical activity remain unclear.

Female Sprague-Dawley rats were ovariectomized (OVX) and concurrently bilaterally implanted with cannulae targeting the nucleus accumbens brain region, traditionally associated with reward and addiction. Daily voluntary wheel running (VWR) was tracked before and after OVX. One month after surgery, rats were treated with intra-accumbens microinjections (0.5 μL total volume) of one of three doses of E2: 0.6 μg/μL (low), 1.5 μg/μL (moderate), or 10 μg/μL (high).

Daily VWR was significantly increased by intra-accumbens E2 microinjections in a non-rapid manner that persisted 48 h following microinjections.

Findings demonstrate for the first time that intra-accumbens E2 partially rescues OVX-induced decreases in daily wheel running.