Hormonal regulation of vasotocin receptor mRNA in a seasonally breeding songbird

Abstract

Behaviors associated with breeding are seasonally modulated in a variety of species. These changes in behavior are mediated by sex 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 nonapeptides vasopressin (VP) and oxytocin (OT) in mammals, and vasotocin (VT) in birds. The effects of testosterone (T) on production of these neuropeptides have been well-studied; however, the regulation of VT receptors by T is not well understood. In this study, we investigated steroid-dependent regulation of VT receptor (VTR) mRNA in a seasonally breeding songbird, the white-throated sparrow (Zonotrichia albicollis). We focused on VTR subtypes that have been most strongly implicated in social behavior: V1a and oxytocin-like receptor (OTR). Using in situ hybridization, we show that T-treatment of non-breeding males altered V1a and OTR mRNA expression in several regions associated with seasonal reproductive behaviors. For example, T-treatment increased V1a mRNA expression in the medial preoptic area, bed nucleus of the stria terminalis, and ventromedial hypothalamus. T-treatment also affected both V1a and OTR mRNA expression in nuclei of the song system; some of these effects depended on the presence or absence of a chromosomal rearrangement that affects singing behavior, plasma T, and VT immunolabeling in this species. Overall, our results strengthen evidence that VT helps mediate the behavioral effects of T in songbirds, and suggest that the chromosomal rearrangement in this species may affect the sensitivity of the VT system to seasonal changes in T.

Expression of oxytocin receptors in the zebra finch brain during vocal development

“…*p < 0.05. during the non-breeding season (Smith et al, 1997); in seasonally breeding sparrows, treatment with testosterone reduced song variability in non-breeding adults (Meitzen et al, 2007) and hastened song crystallization in juveniles (Whaling et al, 1995). Treatment of male white-throated sparrows with testosterone reduced OTR mRNA in the arcopallium (Grozhik et al, 2014), suggesting that OTR in this region may be associated with song variability. Our current results are consistent with this idea in that OTR in the capsular region, as well as in the arcopallium overall, appeared to decrease in males after the auditory learning phase.…”

Genoarchitecture of the extended amygdala in zebra finch, and expression of FoxP2 in cell corridors of different genetic profile

“…In birds, the AVT cells are distributed in two separate cell corridors (galliformes: Aste et al 1998; passerines: Panzica et al 1999), one medial (with magnocellular and parvocellular cells) which appears to partly overlap and/or neighbor caudally our preoptic BSTM, and another one lateral (with magnocellular cells) which appears to correspond to our hypothalamic BSTM. These two cell corridors are also visible by expression of vasotocin receptors in zebra finches and other songbirds (Leung et al 2011; Grozhik et al 2014). In these studies, only the medial corridor is called BSTM, but the lateral one has been suggested to be part of this nucleus (Fig.…”

Vasopressin and oxytocin receptor systems in the brain: Sex differences and sex-specific regulation of social behavior

“…However, short photoperiod-induced anestrus female Syrian hamsters have lower V1aR binding in the medial preoptic nucleus, MPOA, LH, CeA, and BNST compared to females on a long photoperiod (Caldwell and Albers, 2004b), suggesting gonadal hormonal control of V1aR in various brain regions of both male and female hamsters. Furthermore, testosterone treatment increased vasotocin V1aR binding in nuclei of the song system in female canaries (Voorhuis et al, 1988) and male white-throated sparrows (Grozhik et al, 2014). …”