Morphological Interactions between Glial Fibrillary Acidic Protein (GFAP)-like Immunoreactive Elements and Lutenizing Hormone Releasing Hormone (LHRH)-like Immunoreactive Nerve Endings in the Median Eminence of the Rat. Double Labeling Immunoelectron Microscopic Study.

Abstract

In the present study, interactions between lutenizing hormone releasing hormone (LHRH) -like immunoreactive (LHRH-LI) nerve endings and processes of tanycytes and/or astrocytes in the median eminence (ME) particularly its external layer were investigated by double labeling immunoelectron microscopy employing antibodies against glial fibrillary acidic protein (GFAP) and LHRH. GFAP-like immunoreactivity was observed in some tanycytes throughout the ME and/or astrocytes in the subependymal layer of the ME. In the palisade layer of the ME, GFAP-like immunoreactive (GFAP-LI) elements were frequently seen to make intimate contact with LHRH-LI nerve endings. LHRH-LI nerve endings and processes of the tanycytes and/or astrocytes were also found to direct contact with the basement membrane of the pericapillary space. And they were partially engulfed each other in the vicinity of the perivascular region. The above findings strongly suggest that the processes of tanycytes and/or astrocytes with intimate communication of cerebrospinal fluid in the third ventricle may play a role in regulation of secretion of LHRH into the portal vessels.