IGF-I is synthesized in the human and rat anterior pituitary glands. The present study was designed to clarify the growth-promoting action of IGF-I on mouse pituitary cells in a primary serum-free culture system. Proliferation of pituitary cells was detected by monitoring the cellular uptake of bromodeoxyuridine (BrdU). BrdU labelling in the nucleus was found in all types of secretory cells: corticotrophs, thyrotrophs, gonadotrophs (LH cells and FSH cells), somatotrophs and mammotrophs. IGF-I (75 ng/ml) stimulated the proliferation of corticotrophs and mammotrophs among the pituitary secretory cells. IGF-I receptor mRNA was detected in the cultured pituitary cells using reverse transcription (RT)-PCR, indicating that mouse pituitary cells expressed IGF-I receptors. Insulin (100 ng/ml) or IGF-I (7.5 ng/ml) failed to increase the percentage of BrdU-labelled cells. However, treatment with insulin (100 ng/ml) plus IGF-I (7.5 ng/ml) increased the percentage of BrdU-labelled cells in a synergistic-like manner. Genistein, a tyrosine kinase specific inhibitor, decreased the IGF-I-induced cell proliferation, indicating that IGF-I acts through IGF-I receptors. IGF-I mRNA was also detected in the cultured pituitary cells by RT-PCR, and its peptides were immunocytochemically detected. The present results demonstrate that all types of pituitary secretory cells have the ability to proliferate in our serum-free culture system. IGF-I synthesized in the pituitary gland may stimulate the growth of pituitary cells, in particular corticotrophs and mammotrophs, by an autocrine or paracrine mechanism.

This article has been cited by other articles:

				R. M. Luque, G. Amargo, S. Ishii, C. Lobe, R. Franks, H. Kiyokawa, and R. D. Kineman Reporter Expression, Induced by a Growth Hormone Promoter-Driven Cre Recombinase (rGHp-Cre) Transgene, Questions the Developmental Relationship between Somatotropes and Lactotropes in the Adult Mouse Pituitary Gland Endocrinology, May 1, 2007; 148(5): 1946 - 1953. [Abstract] [Full Text] [PDF]

				A. I Arroba, A. M Lechuga-Sancho, L. M Frago, J. Argente, and J. A Chowen Cell-specific expression of X-linked inhibitor of apoptosis in the anterior pituitary of streptozotocin-induced diabetic rats J. Endocrinol., January 1, 2007; 192(1): 215 - 227. [Abstract] [Full Text] [PDF]

				M Fernandez, F Sanchez-Franco, N Palacios, I Sanchez, and L Cacicedo IGF-I and vasoactive intestinal peptide (VIP) regulate cAMP-response element-binding protein (CREB)-dependent transcription via the mitogen-activated protein kinase (MAPK) pathway in pituitary cells: requirement of Rap1 J. Mol. Endocrinol., June 1, 2005; 34(3): 699 - 712. [Abstract] [Full Text] [PDF]

				A. Rose, P. Froment, V. Perrot, M. J. Quon, D. LeRoith, and J. Dupont The Luteinizing Hormone-releasing Hormone Inhibits the Anti-apoptotic Activity of Insulin-like Growth Factor-1 in Pituitary {alpha}T3 Cells by Protein Kinase C{alpha}-mediated Negative Regulation of Akt J. Biol. Chem., December 10, 2004; 279(50): 52500 - 52516. [Abstract] [Full Text] [PDF]

				R. D. Kineman, L. T. Teixeira, G. V. Amargo, K. T. Coschigano, J. J. Kopchick, and L. A. Frohman The Effect of GHRH on Somatotrope Hyperplasia and Tumor Formation in the Presence and Absence of GH Signaling Endocrinology, September 1, 2001; 142(9): 3764 - 3773. [Abstract] [Full Text] [PDF]

				Y. Yamamuro, T. Aoki, and N. Sensui Effect of Estradiol and FBS on PRL Cells, GH Cells, and PRL/GH Cells in Primary Cultures of Pituitary Cells from Prenatal Rats Experimental Biology and Medicine, February 1, 2001; 226(2): 140 - 143. [Abstract] [Full Text]

				J. Schwartz Intercellular Communication in the Anterior Pituitary Endocr. Rev., October 1, 2000; 21(5): 488 - 513. [Abstract] [Full Text]

				D. M. Baker, B. Davies, W. W. Dickhoff, and P. Swanson Insulin-Like Growth Factor I Increases Follicle-Stimulating Hormone (FSH) Content and Gonadotropin-Releasing Hormone-Stimulated FSH Release from Coho Salmon Pituitary Cells In Vitro Biol Reprod, September 1, 2000; 63(3): 865 - 871. [Abstract] [Full Text]

				G. V. Shah, J. Chien, Y. P. Sun, S. Puri, and R. Ravindra Calcitonin Inhibits Anterior Pituitary Cell Proliferation in the Adult Female Rats Endocrinology, September 1, 1999; 140(9): 4281 - 4291. [Abstract] [Full Text]