Simultaneous localization of Pit-1 protein and gonadotropins on the same cell type in the anterior pituitary glands of the rat.
Pit-1 is a prototypic member of the POU transcription factor family and plays a critical role in pituitary-specific action of growth hormone (GH), prolactin (PRL), and thyroid-stimulating hormone (TSH) beta-subunit genes. The purpose of the present study was to elucidate the changes in the expression of the Pit-1 product in the pituitary of pregnant rats employing an improved double-immunohistochemical method. The positive cells showed nuclear immunoreactivity and Pit-1 protein was frequently observed in the nuclei of many cells which were also immunopositive for GH, PRL, and betaTSH. Unexpectedly, a significant number of pituitary cells containing both Pit-1 and gonadotropins were also observed. These cells were usually distributed near blood vessels that supply the pituitary. While a prominent increase in the percentage of Pit-1/PRL, Pit-1/beta-luteinizing hormone and Pit-1/beta-follicle-stimulating hormone immunoreactive cells was observed in pregnant rats, the percentage of Pit-1/GH immunoreactive cells was strongly decreased. In contrast, no significant differences in the percentage of Pit-1/betaTSH doubly immunolabeled cells were noticed. Our findings strongly support the hypothesis that PRL could coexist in the Pit-1 immunopositive gonadotropes. Although Pit-1 protein was not detected in the nuclei of corticotropes, the existence of these cells in the rat pituitary cannot be excluded.
Vidal
S
S
Department of Anatomy, Faculty of Veterinary Sciences, University of Santiago de Compostela, Lugo, Spain. svidal@secuslugo.lugo.usc.es
Román
A
A
Oliveira
M C
MC
De La Cruz
L F
LF
Moya
L
L
D000818:Animals; D002452:Cell Count; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005260:Female; D005640:Follicle Stimulating Hormone / Q000378:metabolism; D037201:Follicle Stimulating Hormone, beta Subunit; D006065:Gonadotropins, Pituitary / Q000378:metabolism*; D013006:Growth Hormone / Q000378:metabolism; D007124:Immunoenzyme Techniques; D007986:Luteinizing Hormone / Q000378:metabolism; D009687:Nuclear Proteins / Q000378:metabolism; D010903:Pituitary Gland, Anterior / Q000166:cytology / Q000378:metabolism*; D011247:Pregnancy; D011388:Prolactin / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D013972:Thyrotropin / Q000378:metabolism; D050817:Transcription Factor Pit-1; D014157:Transcription Factors / Q000378:metabolism*
D004268:DNA-Binding Proteins; D037201:Follicle Stimulating Hormone, beta Subunit; D006065:Gonadotropins, Pituitary; D009687:Nuclear Proteins; C494186:Pou1f1 protein, rat; D050817:Transcription Factor Pit-1; D014157:Transcription Factors; D011388:Prolactin; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone; D013972:Thyrotropin; D013006:Growth Hormone