Merullo Devin P, Spool Jeremy A, Zhao Changjiu, Riters Lauren V
Department of Integrative Biology, University of Wisconsin-Madison, Madison, WI, 53706, USA.
Department of Integrative Biology, University of Wisconsin-Madison, Madison, WI, 53706, USA.
J Chem Neuroanat. 2018 Apr;89:1-10. doi: 10.1016/j.jchemneu.2018.01.002. Epub 2018 Jan 31.
Animals communicate in distinct social contexts to convey information specific to those contexts, such as sexual or agonistic motivation. In seasonally-breeding male songbirds, seasonal changes in day length and increases in testosterone stimulate sexually-motivated song directed at females for courtship and reproduction. Dopamine and testosterone may act in the same brain regions to stimulate sexually-motivated singing. The neuropeptide neurotensin, acting at the neurotensin receptor 1 (NTR1), can strongly influence dopamine transmission. The goal of this study was to gain insight into the degree to which seasonal changes in physiology modify interactions between neurotensin and dopamine to adjust context-appropriate communication. Male European starlings were examined in physiological conditions that stimulate season-typical forms of communication: late summer/early fall non-breeding condition (low testosterone; birds sing infrequently), late fall non-breeding condition (low testosterone; birds produce non-sexually motivated song), and spring breeding condition (high testosterone; males produce sexually-motivated song). Double fluorescent immunolabeling was performed to detect co-localization patterns between tyrosine hydroxylase (TH; the rate-limiting enzyme in dopamine synthesis) and NTR1 in brain regions implicated in motivation and song production (the ventral tegmental area, medial preoptic nucleus, periaqueductal gray, and lateral septum). Co-localization between TH and NTR1 was present in the ventral tegmental area for all physiological conditions, and the number of co-localized cells did not differ across conditions. Immunolabeling for TH and NTR1 was also present in the other examined regions, although no co-localization was seen. These results support the hypothesis that interactions between NTR1 and dopamine in the ventral tegmental area may modulate vocalizations, but suggest that testosterone- or photoperiod-induced changes in NTR1/TH co-localization do not underlie seasonally-appropriate adjustment of communication.
动物在不同的社会环境中进行交流，以传达特定于这些环境的信息，比如性动机或争斗动机。在季节性繁殖的雄性鸣禽中，日照长度的季节性变化和睾酮水平的升高会刺激雄性为求偶和繁殖而向雌性发出具有性动机的歌声。多巴胺和睾酮可能在相同的脑区发挥作用，以刺激具有性动机的鸣叫。神经肽神经降压素作用于神经降压素受体1（NTR1），可强烈影响多巴胺传递。本研究的目的是深入了解生理上的季节性变化在多大程度上改变神经降压素和多巴胺之间的相互作用，从而调节与环境相适应的交流。对雄性欧洲椋鸟在刺激典型季节性交流形式的生理条件下进行了研究：夏末/秋初非繁殖状态（睾酮水平低；鸟类很少鸣叫）、秋末非繁殖状态（睾酮水平低；鸟类发出非性动机的歌声）和春季繁殖状态（睾酮水平高；雄性发出具有性动机的歌声）。进行了双重荧光免疫标记，以检测在与动机和歌声产生相关的脑区（腹侧被盖区、内侧视前核、导水管周围灰质和外侧隔）中酪氨酸羟化酶（TH；多巴胺合成中的限速酶）和NTR1之间的共定位模式。在所有生理条件下，腹侧被盖区均存在TH和NTR1的共定位，且共定位细胞的数量在不同条件下并无差异。在其他检测区域也存在TH和NTR1的免疫标记，不过未观察到共定位现象。这些结果支持了以下假说：腹侧被盖区中NTR1和多巴胺之间的相互作用可能调节发声，但表明睾酮或光周期诱导的NTR1/TH共定位变化并非季节性适当交流调节的基础。
