Steroidal regulation of vasotocin receptor mRNA in a seasonally breeding songbird Pubblico

Grozhik, Anna Vladimirovna (2012)

Permanent URL: https://etd.library.emory.edu/concern/etds/xp68kg791?locale=it
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Abstract


Abstract
Steroidal regulation of vasotocin receptor mRNA in a seasonally breeding songbird
Behaviors associated with breeding are often seasonally modulated in a variety of species.
These seasonal changes in behavior are mediated by gonadal steroids, levels of which likewise
vary with season. The effects of androgens on behaviors associated with breeding may in turn
be partly mediated by the neurohypophyseal nonapeptides vasopressin (VP) and oxytocin (OT)
in mammals, and vasotocin (VT) in birds. The effects of testosterone (T) on production of these
neuropeptides has been well-investigated; however, the regulation of VT receptors
well understood. In this study, I investigated steroidal regulation of VT receptor (VTR) mRNA in
a seasonally breeding songbird, the white-throated sparrow ( Zonotrichia albicollis). VTRs and
their mammalian homologues occur as several subtypes, and I focused on subtypes that have
been most strongly implicated in social behavior: V1a, which bears the same name as its
mammalian homologue, and OT-like receptor, which is homologous to mammalian OT receptor
(OTR). Using in situ hybridization, I showed that in response to T treatment, V1a and OT-like
receptor expression was altered in several regions associated with seasonal reproductive
behaviors such as song. In some regions, the effects of T treatment depended on the presence
or absence of a chromosomal rearrangement that affects singing behavior, plasma
testosterone, and VT immunolabeling in this species. Overall, the results of this study
strengthen evidence that VT may mediate T's behavioral effects in songbirds, and suggest that
the chromosomal rearrangement in this species may affect the sensitivity of the vasotocin
system to seasonal changes in T.

Table of Contents

Table of Contents
Introduction 1
Methods 4
Results 10
Discussion 12
References 19
Tables 28
Figures 29


















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