Goebrecht Geraldine K E, Kowtoniuk Robert A, Kelly Brenda G, Kittelberger J Matthew
Department of Biology, Gettysburg College, 300 North Washington Street, Gettysburg, PA 17325, USA.
J Chem Neuroanat. 2014 Mar;56:13-34. doi: 10.1016/j.jchemneu.2014.01.001. Epub 2014 Jan 10.
Vocal communication has emerged as a powerful model for the study of neural mechanisms of social behavior. Modulatory neurochemicals postulated to play a central role in social behavior, related to motivation, arousal, incentive and reward, include the catecholamines, particularly dopamine and noradrenaline. Many questions remain regarding the functional mechanisms by which these modulators interact with sensory and motor systems. Here, we begin to address these questions in a model system for vocal and social behavior, the plainfin midshipman fish (Porichthys notatus). We mapped the distribution of immunoreactivity for the catecholamine-synthesizing enzyme tyrosine hydroxylase (TH) in the midshipman brain. The general pattern of TH(+) cell groups in midshipman appears to be highly conserved with other teleost fish, with a few exceptions, including the apparent absence of pretectal catecholamine cells. Many components of the midshipman vocal and auditory systems were innervated by TH(+) fibers and terminals, including portions of the subpallial area ventralis, the preoptic complex, and the anterior hypothalamus, the midbrain periaqueductal gray and torus semicircularis, several hindbrain auditory nuclei, and parts of the hindbrain vocal pattern generator. These areas thus represent potential sites for catecholamine modulation of vocal and/or auditory behavior. To begin to test functionally whether catecholamines modulate vocal social behaviors, we hypothesized that male and female midshipman, which are sexually dimorphic in both their vocal-motor repertoires and in their responses to hearing conspecific vocalizations, should exhibit sexually dimorphic expression of TH immunoreactivity in their vocal and/or auditory systems. We used quantitative immunohistochemical techniques to test this hypothesis across a number of brain areas. We found significantly higher levels of TH expression in male midshipman relative to females in the TH cell population in the paraventricular organ of the diencephalon and in the TH-innervated torus semicircularis, the main teleost midbrain auditory structure. The torus semicircularis has been implicated in sexually dimorphic behavioral responses to conspecific vocalizations. Our data thus support the general idea that catecholamines modulate vocal and auditory processing in midshipman, and the specific hypothesis that they shape sexually dimorphic auditory responses in the auditory midbrain.
声音交流已成为研究社会行为神经机制的有力模型。据推测，与动机、唤醒、激励和奖赏相关的、在社会行为中起核心作用的调节性神经化学物质包括儿茶酚胺，尤其是多巴胺和去甲肾上腺素。关于这些调节剂与感觉和运动系统相互作用的功能机制，仍有许多问题。在此，我们开始在一个声音和社会行为的模型系统——光腹角鲨（Porichthys notatus）中解决这些问题。我们绘制了角鲨脑中儿茶酚胺合成酶酪氨酸羟化酶（TH）免疫反应性的分布。角鲨中TH(+)细胞群的总体模式似乎与其他硬骨鱼高度保守，只有少数例外，包括视前区明显没有儿茶酚胺细胞。角鲨声音和听觉系统的许多组成部分都由TH(+)纤维和终末支配，包括腹侧皮质下区、视前复合体、下丘脑前部、中脑导水管周围灰质和半规管隆起、几个后脑听觉核以及后脑声音模式发生器的部分区域。因此，这些区域代表了儿茶酚胺调节声音和/或听觉行为的潜在部位。为了开始从功能上测试儿茶酚胺是否调节声音社会行为，我们假设，在声音运动行为模式和对同种声音的反应上都具有性别二态性的雄性和雌性角鲨，其声音和/或听觉系统中TH免疫反应性应表现出性别二态性表达。我们使用定量免疫组织化学技术在多个脑区测试了这一假设。我们发现，在间脑室旁器官的TH细胞群体以及TH支配的半规管隆起（硬骨鱼主要的中脑听觉结构）中，雄性角鲨的TH表达水平相对于雌性显著更高。半规管隆起与对同种声音的性别二态性行为反应有关。因此，我们的数据支持了儿茶酚胺调节角鲨声音和听觉处理的总体观点，以及它们塑造听觉中脑性别二态性听觉反应的具体假设。
