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.
Department of Anatomy, Faculty of Veterinary Sciences, University of Santiago de Compostela, Lugo, Spain. svidal@secuslugo.lugo.usc.es
S
S
Vidal
A
A
Román
M C
MC
Oliveira
L F
LF
De La Cruz
L
L
Moya
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