Resumen de Characterization of GFAP expression and cell proliferation in the rat median eminence following hypophysectomy
Ricardo Vázquez, Enrique J. Blanco Barco, Fernando Sánchez Hernández, Juan Antonio Juanes Méndez, Manuel Rubio Sánchez, Miguel Santos del Rey, G. Vázquez, E. Hernández, José Manuel Riesco Santos, José Carretero González
To analyze whether the reorganization of the rat median eminence after hypo physecto my might be re la ted to cha nges in glia l fibrilla ry acidic pro te in (GFAP)-and ce llular proliferation, the distributio n of cells immunoreactive fo r GFAP and the proliferation rate of such cells were analyzed at 20, 40 and 60 days post-hypophysecto my. For this study, fo ur rost ra -cauda l regions of the median eminence were differentiated: the re trochiasmatic, p reinfundibula r, infundibul a r a nd postinfundibular r egions. In each of these regio ns, three layers were studied: the ependymal, the internal and the external. A t 20 and 40 days afte r hypo physecto my, significant increases in ce llular proliferation affecting all three layers studie d in th e preinfundib ul a r a nd infund ibula r regio ns were found. At th e sa me time po ints, in c reases in G FA P expressio n were also observed. However, afte r 60 days, GFAP a nd proliferative ce llular nuclea r antigen (PCNA) expression decreased . Altho ug h variatio ns of PC NA a nd GFAP leve ls were evident, no colocalisatio n of PC NA and GFAP was found in the cells of the median eminence in untreated o r hypophysec tomized rats when sections were analyzed by double immunohistochemica l staining. Our results suggest that reorganizatio n of median eminence in volves a lt e r a ti o ns (or modula ti o n) of GFAP-immuno reactive cells togethe r with a pro life ratio n of cells that are not GFAP-immuno reactive. This study also demonstrates that this reorganizatio n is completed within the first t wo months after hypophysectomy.
