引言这项研究旨在破译季节性繁殖的亚热带雀科的生活史阶段之间的过渡机制,Amandavaamandava描绘了促性腺激素(LH细胞)的可塑性,包括结节旁(PT)在内的垂体中的催乳素(PRL细胞)和促甲状腺激素(TSH细胞),关于原位表达,形态特征,和血浆激素水平的改变。方法LH的免疫组织化学,PRL,TSH细胞,表达激素的形态计量学和密度测定(ImgeJ软件分析),和ELISA检测血浆激素水平。结果LH,PRL和TSH细胞在每年的季节性生殖周期中表现出明显的可塑性。在PT中,在繁殖阶段检测到所有三种细胞类型,进一步检测前育种期间的TSH免疫反应性和后育种阶段的PRL免疫反应性。在繁殖阶段,远端肌(PD)表达和血浆LH和TSH水平处于峰值,但PRL高峰是在繁殖后阶段。除了神经垂体和正中隆起的PRL,还阐明了下丘脑PRL和TSH。结论这项研究表明,PTTSH激活性腺轴,这可能会转导季节性线索,但不是特别光周期,在热带/亚热带的鸟类中。繁殖后阶段持续的高血浆TSH和峰值血浆PRL可能会协调向非繁殖阶段的过渡,包括引发父母照护的触发,作为后来的激素分配。下丘脑TSH和PRL可能通过中枢调节影响季节性事件。
BACKGROUND: This study sought to decipher the mechanism of transitions between life-history stages in a seasonally reproducing subtropical finch, Amandava amandava delineating the plasticity of the gonadotropes (LH cells), lactotropes (PRL cells), and thyrotropes (TSH cells) in the pituitary gland including the pars tuberalis, with regard to the in situ expression, morphological characteristics, and alteration in the plasma levels of hormones.
METHODS: Immunohistochemistry of LH, PRL, TSH cells, morphometry and densitometry of expressed hormones (Image J software analysis), and ELISA for plasma hormonal levels were performed.
RESULTS: LH, PRL, and TSH cells showed remarkable plasticity during the annual seasonal reproductive cycle. In the PT, all the 3 cell types were detected during the breeding phase, with additional detection of the TSH immunoreactivity during the pre-breeding and the PRL immunoreactivity during post-breeding phases. Pars distalis (PD) expressions and the plasma levels of the LH and TSH were at the peak during the breeding phase, but the PRL peak was during the post-breeding phase. In addition to PRL in the neurohypophysis and in the median eminence, hypothalamic PRL, and TSH were also elucidated.
CONCLUSIONS: This study suggests activation of the gonadal axis by the PT TSH which might transduce seasonal cues, but not specifically photoperiod, in the birds of the tropics/subtropics. Post-breeding phase sustained high plasma TSH and peak plasma PRL might coordinate the transition to the non-breeding phase including the trigger of parental care as the later hormone assigned with. Hypothalamic TSH and PRL might influence events of seasonality through central modulation.