| dc.description.abstract |
<p>The song system of the zebra finch (Taeniopygia guttata) is highly sexually dimorphic,
where only males develop the neural structures necessary to learn and produce learned
vocalizations in adulthood. During early development, both males and females begin
to develop their song system in a monomorphic manner, which diverges shortly after
the onset of a critical sensory learning phase and results in reduced cell survival
and proliferation in females, and accelerated cell proliferation in males. Estrogen
has long been known to be involved in coordinating sexual development of the perinatal
brain and nestling female zebra finches treated with estrogen do not exhibit this
female-specific atrophy of the song system. How estrogen influences the development
of the song system, and what it is doing at the molecular level has not been examined
utilizing current generation sequencing technology.</p><p>In this dissertation, I
tested whether estrogen manipulation impacts the transcriptomic profiles of telencephalic
song learning nuclei in males and females. I treated animals with either vehicle,
exemestane (an estrogen synthesis inhibitor), or 17-β-estradiol from the moment of
hatching until time of sacrifice. I collected the song learning nuclei and their surrounding
brain regions during the onset of sensory motor learning for transcriptomic analysis
or during adulthood after collecting behavior. I found that of the 4 telencephalic
song nuclei examined during the onset of the sensorimotor learning period at post
hatch day 30, Area X was the most sexually dimorphic and the most impacted by estrogen
administration. HVC was less sexually dimorphic and less impacted by estrogen manipulation.
RA and LMAN had limited sexually dimorphic features, with little impact on their transcriptomes
with estrogen manipulation. Additionally, I found that chronic estrogen depletion
in males delayed male specific plumage development and resulted in impaired song learning.
This supports the notion that while estrogen is sufficient in preventing atrophy of
the song system in female zebra finches, it is not necessary for the gross development
in males and may instead refine normal song development.</p>
|
|
