Departamento de Biodiversidad y Biología Experimental, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, (C1428EHA), Buenos Aires, Argentina.
Physiol Behav. 2012 May 15;106(2):193-200. doi: 10.1016/j.physbeh.2012.02.002. Epub 2012 Feb 9.
The South American cichlid fish Cichlasoma dimerus is a freshwater species that presents social hierarchies, a highly organized breeding activity, biparental care and a high frequency of spawning. Spawning is followed by a period of parental care (about 20 days in aquaria conditions) during which the cooperative pair takes care of the eggs, both by fanning them and by removing dead ones. The different spawning events in the reproductive period were classified as female reproductive stages which can be subdivided in four phases, according to their offspring degree of development: (1) female with prespawning activity (day 0), (2) female with eggs (day 1 after fertilization), (3) female with hatched larvae (day 3 after fertilization) and (4) female with swimming larvae (FSL, day 8 after fertilization). In Perciform species gonadotropin-releasing hormone type-3 (GnRH3) neurons are associated with the olfactory bulbs acting as a potent neuromodulator of reproductive behaviors in males. The aim of this study is to characterize the GnRH3 neuronal system in females of C. dimerus in relation with aggressive behavior and reproductive physiology during different phases of the reproductive period. Females with prespawning activity were the most aggressive ones showing GnRH-3 neurons with bigger nuclear and somatic area and higher optical density than the others. They also presented the highest levels of plasma androgen and estradiol and maximum gonadosomatic indexes. These results provide information about the regulation and functioning of hypothalamus-pituitary-gonads axis during reproduction in a species with highly organized breeding activity.
南美慈鲷鱼 Cichlasoma dimerus 是一种淡水物种，具有社会等级制度、高度组织化的繁殖活动、双亲照顾和高频率的产卵。产卵后，会有一段亲代照顾期（在水族箱条件下约 20 天），在此期间，合作的雌雄鱼会照顾卵，包括扇动它们和清除死卵。繁殖期的不同产卵事件被归类为雌性生殖阶段，根据其后代的发育程度可进一步细分为四个阶段：（1）有产卵活动的雌性（第 0 天），（2）有卵的雌性（受精后第 1 天），（3）有孵化幼虫的雌性（受精后第 3 天）和（4）有游动幼虫的雌性（FSL，受精后第 8 天）。在鲈形目物种中，促性腺激素释放激素 3 型（GnRH3）神经元与嗅球有关，作为雄鱼生殖行为的有效神经调节剂。本研究旨在描述 C. dimerus 雌性中的 GnRH3 神经元系统与不同繁殖阶段的攻击性行为和生殖生理的关系。有产卵活动的雌性最具攻击性，其 GnRH-3 神经元的核和体面积以及光密度均大于其他雌性。它们还表现出最高水平的血浆雄激素和雌二醇以及最大的性腺指数。这些结果提供了有关在具有高度组织化繁殖活动的物种中，下丘脑-垂体-性腺轴在繁殖过程中的调节和功能的信息。
