How does Estrogen Influence Attention? Impact of 17‐beta Estradiol on Performance in an Attentional Set Shifting Task

Abstract

Estrogens have been shown to affect learning and memory in female rats. ADHD is 3–9× more prevalent in males, suggesting that gonadal hormones may be in part responsible for the observed disparity between the sexes. In this disorder dopamine and norepinephrine levels in the ventromedial prefrontal cortex may be deficient, as evidenced by the use of stimulants to treat this disorder. Estrogen has been shown to inhibit dopamine reuptake in the prefrontal cortex this increasing extracellular levels of dopamine. Our previous work has suggested that in ovariectomized female rats, estradiol supplementation yielded higher levels of dopamine in the PFC than in male rats (1). The purpose of the present study was to evaluate the effect of estrogen in ovariectomized (OVX) female Long‐Evans rats in the attentional set‐shifting task (ASST)(2), a measure of attention which is strongly associated with monoamine levels in the vmPFC. Adult female rats were ovariectomized (OVX) or underwent a sham surgery. OVX rats were then randomized into two groups and given injections of 21 ug/kg 17‐B‐estradiol or vehicle every other day for the remainder of the study, while sham surgery animals were given vehicle injections. Rats were then tested in the ASST, wherein rats are trained to dig in pots for food reward. Pots are labeled with three dimensions, scent, digging material and texture of the pot and trained to dig for a food reward. Once the animal reaches criteria performance in a simple discrimination (SD) and then a complex discrimination (CD), the animal is then tested for performance in the intradimensional shift (ID), followed by a reversal (IDR). The animal is then exposed to an extradimensional shift (odor to digging material) (ED), followed by the reversal within this ED (EDR). This study found that OVX rats performed better in the ASST than sham or OVX + E animals, possibly reflecting a complicated dose‐response relationship to 17‐B‐estradiol administration. Further studies are underway to assess the levels of dopamine, norepinephrine, and serotonin in the ventromedial prefrontal cortex of these animals using in vivo microdialysis.Support or Funding InformationSC supported by a Morgane Research Fellowship from UNECOM.