神经肽Y和β-内啡肽样免疫阳性物质在文昌鱼神经系统和哈氏窝的分布

DISTRIBUTION OF NEUROPEPTIDE Y-LIKE AND β-ENDORPHIN-LIKE IMMUNOREACTIVITY IN THE NERVOUS SYSTEM AND HATSCHEK'S PIT OF AMPHIOXUS, BRANCHIOSTOMA BELCHERI

用免疫组织化学方法首次发现,神经肽Y(NPY)和β-内啡肽(β-Ep)样免疫阳性物质分布在文昌鱼神经系统和哈氏窝。NPY样免疫阳性神经元出现在端脑前部和中部、中脑前部和中部以及后脑,NPY样免疫阳性神经纤维在文昌鱼脑的各部分与神经元交错呈网状密集分布。神经管的背面与中部均可观察到NPY样免疫阳性神经元及其阳性纤维。β-Ep样免疫阳性神经元及其神经纤维定位在中脑前部和中部以及神经管,且分布范围明显小于NPY。文昌鱼哈氏窝也有NPY和β-Ep样免疫阳性物质分布。这些结果表明,NPY和β-Ep可能作为脑内的一种神经递质,像鱼类那样,参与调节文昌鱼哈氏窝促性腺激素分泌细胞的分泌活动,这为文昌鱼脑-哈氏窝复合体的密切关系提供新的形态学证据。

Using immunohischemical method, we have localized for the first time in the amphioxus, Bran-chiostama belcheri, neuropeptide Y (NPY)-like and β-endorphin (β-Ep)-like immunoreactivity in nervous system and Hatschek's pit. NPY-immunoreactive (-ir) perikarya appeared in the front and middle areas of the telencephalon and midbrain, as well as in the hindbrain. Dense plexuses of NPY-ir fibers coursed with NPY-ir neurons and formed fine networks. NPY-ir perikarya and fibers were observed in the dorsal and middle areas of spinal cord. β-Ep-like immunoreactive perikarya and fibers were located in the front and middle areas of the midbrain, as well as in the spinal cord, but not in the telencephalon and hindbrain. The regions showing β-Ep immunoreactivity were less than that of NPY. NPY-like and β-Ep-like immunoreactivity were also found in the Hatschek's pit of amphioxus. These results suggest that NPY and β-Ep, as an neurotransmitter as in fish, may be involved in the regulation of Hatschek's pit gonadotrophic cells secretory activity in amphioxus, and provide a new morphological evidence for the close relationship between brain and Hatschek s pit in amphioxus.