Morphometric evaluation of subcellular changes induced by in vivo TRH treatment in the pituitary gland of Rana perezi: effects on prolactin and thyrotropic cells.
The effects of synthetic thyrotropin-releasing hormone on pituitary prolactin and thyrotropic cells were investigated in adult male Rana perezi (formerly Rana ridibunda) frogs. Animals were given daily injections of synthetic thyrotropin-releasing hormone into the dorsal lymph sac. Prolactin and thyrotropic cells were identified by the colloidal-gold method, using anti-human prolactin and anti-human-beta-thyrotropin hormone as primary antisera. The stereological parameters of the rough endoplasmic reticulum, Golgi complex, and secretory granules of prolactin and thyrotropic cells were evaluated by ultrastructural morphometry (point-counting method). Thyrotropin-releasing hormone caused cytological changes in both cell-types which were consistent with increased synthesis and release of both prolactin and thyrotropin. These changes were still significant after 48 h treatment in the case of thyrotropic cells, while in prolactin cells the thyrotropin-releasing hormone increased the number of secretory granules. After 6 days, the cells resembled essentially those used as controls. These results indicate that thyrotropin-releasing hormone stimulates the synthesis and release of prolactin and thyrotropin, and that the response of each cell type to this hypothalamic stimulus follows a different time-course.
Malagón
M M
MM
Department of Cell Biology, University of Córdoba, Spain.
García-Navarro
S
S
Ruiz-Navarro
A
A
Gracia-Navarro
F
F
D000818:Animals; D003594:Cytoplasmic Granules / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D008297:Male; D008854:Microscopy, Electron; D010902:Pituitary Gland / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D011388:Prolactin / Q000378:metabolism*; D011898:Ranidae; D013972:Thyrotropin / Q000378:metabolism*; D013973:Thyrotropin-Releasing Hormone / Q000494:pharmacology*; D013997:Time Factors
D013973:Thyrotropin-Releasing Hormone; D011388:Prolactin; D013972:Thyrotropin