Cánepa Maximiliano, Pozzi Andrea, Astola Antonio, Maggese María Cristina, Vissio Paula
Laboratorio de Embriología Animal, Departamento de Biodiversidad y Biología Experimental, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, C1428EHA, Buenos Aires, Argentina.
Cell Tissue Res. 2008 Jul;333(1):49-59. doi: 10.1007/s00441-008-0622-8. Epub 2008 May 28.
We detected a close morphological association between melanin-concentrating hormone (MCH)-immunoreactive (ir) fibers and somatolactin (SL)-ir cells in the pars intermedia of the cichlid fish Cichlasoma dimerus by double-label immunofluorescence. Male pituitaries obtained from adult C. dimerus were incubated with 0.1-10 microM salmon MCH, and the amount of SL released into the culture medium was semi-quantified by Western blot. This assay showed an increase of SL release in a dose-dependent manner (linear regression: P<0.05). A close association of GnRH-ir fibers with SL-ir cells was also detected at the pars intermedia level. Male pituitaries were also incubated with 0.1-10 microM of mammalian GnRH, and SL release was semi-quantified by Western blot, showing an increase of released SL levels in a dose-dependent manner (linear regression: P<0.05). In contrast, SL release was unaffected from female pituitaries incubated with salmon MCH; however, an increasing tendency was observed when mammalian GnRH was used. Hypothalamic close association of MCH-ir perikarya and GnRH-ir fibers was found by double-label immunofluorescence indicating a possible relationship between them. These results suggest that SL, like other pituitary hormones, is under hypothalamic control and is involved in diverse physiological processes including background adaptation and reproduction. This study has also shown that the in vitro culture of a single C. dimerus pituitary is a feasible method for studying the control of SL release and other pituitary hormones.
通过双标免疫荧光法，我们在丽鱼科鱼类Cichlasoma dimerus的垂体中间部检测到了黑色素浓缩激素（MCH）免疫反应性（ir）纤维与生长抑素（SL）ir细胞之间紧密的形态学联系。从成年C. dimerus获取的雄性垂体与0.1 - 10微摩尔的鲑鱼MCH一起孵育，通过蛋白质印迹法对释放到培养基中的SL量进行半定量分析。该分析显示SL释放量呈剂量依赖性增加（线性回归：P<0.05）。在垂体中间部水平也检测到了促性腺激素释放激素（GnRH）ir纤维与SL ir细胞的紧密联系。雄性垂体同样与0.1 - 10微摩尔的哺乳动物GnRH一起孵育，通过蛋白质印迹法对SL释放进行半定量分析，结果显示释放的SL水平呈剂量依赖性增加（线性回归：P<0.05）。相反，用鲑鱼MCH孵育雌性垂体时，SL释放不受影响；然而，使用哺乳动物GnRH时则观察到有增加的趋势。通过双标免疫荧光法发现下丘脑MCH ir核周体与GnRH ir纤维紧密联系，表明它们之间可能存在某种关系。这些结果表明，SL与其他垂体激素一样，受下丘脑控制，并参与包括背景适应和繁殖在内的多种生理过程。本研究还表明，单个C. dimerus垂体的体外培养是研究SL释放及其他垂体激素调控的一种可行方法。
