雌、雄激素受体在文昌鱼神经系统和哈氏窝的免疫识别

IMMUNORECOGNITION OF ESTROGEN AND ANDROGEN RECEPTORS IN THE NERVOUS SYSTEM AND HATSCHEK'S PIT OF AMPHIOXOUS (BRANCHIOSTOMA BELCHERI)

用雌、雄激素受体的多克隆抗体对不同发育时期的文昌鱼神经系统和哈氏窝进行免疫识别。结果显示 ,雌、雄激素受体免疫阳性识别发生在文昌鱼端脑和中脑的中部与后部 ,以及神经管的背面和中央 ,后脑则为免疫阴性反应。两种激素受体免疫阳性物多数分布在神经细胞核内及其神经纤维 ,少数在胞质。雌、雄激素受体免疫阳性识别还出现在文昌鱼哈氏窝基部的上皮细胞核内或胞质中。雌、雄激素受体在文昌鱼神经系统和哈氏窝的免疫识别部位与脊椎动物相类似。研究表明 ,性类固醇激素像在脊椎动物中那样 。

Previous studies discovered that Amphioxus ( Branchiostoma bekheri ) had primitive reproductive endocrine regulation axis (brain Hatschek's pit gonads) which synthesizes and secretes sex steriod hormones (estrogen, androgen and progestergone). However, the feedback regulation of sex steroid hormones on brain and Hatschek's pit (homologous with the pituitary gland) of Amphioxus had not been reported so far. Thus, we used polyclonal antibodies against estrogen and androgen receptors to investigate the immuno recognition of estrogen and androgen receptors in nervous system and Hatschek's pit of Amphioxus at different development stages. Amphioxus were collected from the Tong'an Qiongtou sea area near Xiamen. Each fish was divided into three segments, head (from tentaculum peristomial to the first pair of gonads), medial (from the first pair of gonads to the amus) and tail. Samples were fixed in Bouin's solution without acetic acid for 8～12 h, then embedded in paraplast. Sections with the structure of brain and Hatschek's pit were identified under a light microscope and selected for immunostaining with the SABC technique. The results showed that the immuno recognition of estrogen and androgen receptors existed in the telencephalon and the middle and posterior part of midbrain. Immunopositive substances mostly located in the nucleus of nerve cells, with a few in the cytoplasm. The dorsal side and middle region of nerve tube also showed immunopositive reaction, and the immunopositive substances of estrogen and androgen receptors distributed in the nucleus, cytoplasm and nerve fibers of nerve cells. But immunonegative reaction was showed in the hindbrain. On the other hand, immuno recognition of estrogen and androgen receptors existed in the nucleus or the cytoplasm of epithelial cells (primitive gonadotrophic cells in Amphioxus) in the base part of Hatschek's pit at different stages of development. The other two cells in Hatschek's pit showed immunonegative reaction. The results demonstrate for the first time that estrogen and androgen receptors exist in cephalochordata Amphioxus, and the immunorecognitive regions of the estrogen and androgen receptors in the brain and Hatschek's pit are similar to those of vertebrates. It suggests that sex steroid hormones exert feedback regulation on brain and Hatschek's pit, and stimulate the development and maturity of the reproductive endocrine regulation axis function in Amphioxus. These facts further demonstrate a system of reproductive endocrine regulation in Amphioxus similar to, or with close relationship with that in vertebrate. On the other hand, we suggest that the regulatory role of sex steroid hormones on gonads function and reproduction behavior may be direct or indirect through sex steroid hormones receptors in brain.