Colocalization of immediate early genes in catecholamine cells after song exposure in female zebra finches (Taeniopygia guttata)

Abstract

The physiological state of animals in many taxonomic groups can be modified via social interactions including simply receiving communication signals from conspecifics. Here, we explore whether the catecholaminergic system of female songbirds responds during social interactions that are limited to song reception. We measured the protein product of an immediate early gene (ZENK) within three catecholaminergic brain regions in song-exposed (n = 11) and silence-exposed (n = 6) female zebra finches (Taeniopygia guttata). ZENK-ir induction was quantified in catecholamine cells as well as within cells of unknown phenotypes in three brain regions that synthesize catecholamines, the ventral tegmental area, the periaqueductal gray and the locus coeruleus (LoC). Our results reveal that there are no significant differences in the overall number of cells expressing ZENK between song- and silence-exposed females. However, when we limited our measurements to catecholamine-containing cells, we noticed a greater number of catecholamine-containing cells expressing ZENK within the LoC in the song-exposed females compared to silence-exposed females. Furthermore, we measured five behaviors during the song- and silence-exposed period, as behavioral differences between these groups may account for differences in the coinduction of ZENK and TH-ir. Our results reveal that there were no statistically significant differences in the five measured behaviors between song- and silence-exposed females. Our study demonstrates that noradrenergic cells within the LoC are involved in the neural architecture underlying sound perception and that cells within the catecholaminergic system are modulated by social interactions, particularly the reception of signals used in animal communication.

Fig. 1

a, b Three catecholaminergic brain regions investigated in this study. a VTA and PAG in a coronal plane of section. b LoC in a coronal plane of section. Scale bar = 1 mm.

Fig. 2

a VTA cells stained for TH. Scale bar = 10 µm. b TH cells with no ZENK-ir induction within the nucleus. Scale bar = 1 µm. c, d Cells with ZENK-ir within the nucleus of a TH cell. Scale bars = 1 µm.

Fig. 3

a Mean number of ZENK-ir cells within three catecholaminergic nuclei of song-exposed (n = 11) and silence-exposed female zebra finches (n = 6). b Mean number of cells with colocalized TH and ZENK-ir within three catecholaminergic nuclei of song- and silence-exposed female zebra finches. All means are reported ± SEM. Asterisk denotes significant differences between groups.

Fig. 4

a Comparison between the amount of time spent near the speaker and the time spent feeding or drinking between song-exposed (n = 11) and silence-exposed (n = 5) female zebra finches. A bird was considered to be spending time near the speaker if she moved to the same side and corner as the speaker and within approximately 15 cm. b Comparison of the number of flights (either to a new perch or to the ground), grooming behaviors (bill wipes, preening) and movements across the perch between song- and silence-exposed female zebra finches.