Ampatzis Konstantinos, Dermon Catherine R
Biology Department, Laboratory of Human and Animal Physiology, University of Patras, 26500 Rion, Greece; Department of Neuroscience, Karolinska Institutet, 17177 Stockholm, Sweden.
Biology Department, Laboratory of Human and Animal Physiology, University of Patras, 26500 Rion, Greece.
Behav Brain Res. 2016 Oct 1;312:385-93. doi: 10.1016/j.bbr.2016.06.047. Epub 2016 Jun 27.
Sexually dimorphic behaviors and brain sex differences, not only restricted to reproduction, are considered to be evolutionary preserved. Specifically, anxiety related behavioral repertoire is suggested to exhibit sex-specific characteristics in rodents and primates. The present study investigated whether behavioral responses to novelty, have sex-specific characteristics in the neurogenetic model organism zebrafish (Danio rerio), lacking chromosomal sex determination. For this, aspects of anxiety-like behavior (including reduced exploration, increased freezing behavior and erratic movement) of male and female adult zebrafish were tested in a novel tank paradigm and after habituation. Male and female zebrafish showed significant differences in their swimming activity in response to novelty, with females showing less anxiety spending more time in the upper tank level. When fish have habituated, regional cerebral glucose uptake, an index of neuronal activity, and brain adrenoceptors' (ARs) expression (α2-ARs and β-ARs) were determined using in vivo 2-[(14)C]-deoxyglucose methodology and in vitro neurotransmitter receptors quantitative autoradiography, respectively. Intriguingly, females exhibited higher glucose utilization than males in hypothalamic brain areas. Adrenoceptor's expression pattern was dimorphic in zebrafish telencephalic, preoptic, hypothalamic nuclei, central gray, and cerebellum, similarly to birds and mammals. Specifically, the lateral zone of dorsal telencephalon (Dl), an area related to spatial cognition, homologous to the mammalian hippocampus, showed higher α2-AR densities in females. In contrast, male cerebellum included higher densities of β-ARs in comparison to female. Taken together, our data demonstrate a well-defined sex discriminant cerebral metabolic activity and ARs' pattern in zebrafish, possibly contributing to male-female differences in the swimming behavior.
性二态行为和大脑性别差异不仅局限于生殖方面，被认为是进化保守的。具体而言，在啮齿动物和灵长类动物中，与焦虑相关的行为表现被认为具有性别特异性特征。本研究调查了在缺乏染色体性别决定的神经遗传模式生物斑马鱼（Danio rerio）中，对新事物的行为反应是否具有性别特异性特征。为此，在新水箱范式中对成年雄性和雌性斑马鱼的焦虑样行为（包括探索减少、僵住行为增加和运动不稳定）进行了测试，并在适应后进行了检测。雄性和雌性斑马鱼对新事物的游泳活动表现出显著差异，雌性表现出较少的焦虑，在上层水箱区域停留的时间更长。当鱼适应后，分别使用体内2-[(14)C]-脱氧葡萄糖方法和体外神经递质受体定量放射自显影技术测定了区域脑葡萄糖摄取（神经元活动的指标）和脑肾上腺素能受体（ARs）的表达（α2-ARs和β-ARs）。有趣的是，雌性在下丘脑脑区的葡萄糖利用率高于雄性。肾上腺素能受体的表达模式在斑马鱼的端脑、视前区、下丘脑核、中央灰质和小脑中呈二态性，与鸟类和哺乳动物相似。具体而言，背侧端脑外侧区（Dl），一个与空间认知相关的区域，与哺乳动物海马体同源，在雌性中显示出更高的α2-AR密度。相比之下，雄性小脑的β-AR密度高于雌性。综上所述，我们的数据表明斑马鱼中存在明确的性别差异脑代谢活动和ARs模式，这可能导致了游泳行为中的雌雄差异。
