The Role of Serotonin in the Estradiol-dependent Selectivity of Auditory Regions in Songbirds
Abstract
Breeding-typical levels of estradiol in songbirds has been shown to lead to selective auditory processing and induce a release of serotonin in auditory regions of the forebrain. These findings triggered the question of whether auditory discrimination is driven by estradiol directly, or by the associated release of serotonin. I treated non-breeding female white-throated sparrows (Zonotrichia albicollis) with either blank implants, 17β-estradiol, serotonin enhancer and blank implants, or serotonin antagonist and 17β-estradiol implants. Birds then heard male conspecific songs or control tones, and ZENK-immunoreactivity was quantified in the caudomedial nidopallium (NCM) and caudomedial mesopallium (CMM). While I did not find that breeding-typical levels of estradiol drives auditory selectivity in the brain, I did find a significant interaction between treatment and stimulus in the serotonin-enhancer group in the CMM, and clear trends in the same direction in the NCM. This suggests that the previously found effects of estradiol may be mediated by serotonin.