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

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.