Endocrinology, Vol 119, 629-637, Copyright © 1986 by Endocrine Society

ARTICLES

Morphometric studies of rat anterior pituitary cells after gonadectomy: correlation of changes in gonadotropes with the serum levels of gonadotropins

SN Ibrahim, SM Moussa and GV Childs

Anterior pituitary cells were studied with immunocytochemical methods 1- 6 months after gonadectomy in male and female rats. One month after surgery, stained gonadotropes contained small scattered cisternae of rough endoplasmic reticulum, while others showed larger cisternae. The signet ring cells were observed 3 months after gonadectomy, and their numbers increased markedly by 6 months. Counts of freshly dispersed stained cells showed that in intact rats, the only significant sex differences were seen in the percentages of FSH and PRL cells. The females had higher percentages of both cell types. One month after castration, there were 2- and 3-fold increases in the percentages of LH and FSH cells, respectively. In females, ovariectomy resulted in a 2- fold increase in the percentage of LH cells and a slight but not significant increase in that of FSH cells. Three months after surgery, the percentages of LH or FSH gonadotropes increased from 8-12% to about 30% in both sexes. In the 6-month group, the percentages of stained gonadotropes were decreased to about 20% in both males and females. Counts of other pituitary cell types showed that the percentage of PRL cells in females declined to levels similar to those in the male within 1 month after ovariectomy. There was also a significant increase in the percentage of GH cells 1-3 months after ovariectomy. In contrast, the percentages of GH-producing cells decreased in the castrated males 3-6 months after surgery. The other pituitary cell types (ACTH and TSH) did not show significant changes after gonadectomy in either sex. The average area of gonadotropes was increased gradually, reaching a maximum 3 months after gonadectomy, after which it was decreased in the 6-month group. After ovariectomy, serum levels of gonadotropins correlated well with changes in areas of gonadotropes, showing a continuous increase until the third month, followed by a decrease after 6 months. Serum LH levels increased and then decreased after castration following the same pattern as that of the average areas. However, serum FSH levels continued to increase gradually throughout the entire 6 months. These studies are the first to quantify changes in all six pituitary cell types after gonadectomy. The counts confirm qualitative data reported previously that show changes in GH and PRL cells after gonadectomy (including sex differences). We extend previous studies that show that the expansion in gonadotropic cell area is correlated with a rise in both serum LH and FSH.

This article has been cited by other articles:

				Z. Naor, H. N. Jabbour, M. Naidich, A. J. Pawson, K. Morgan, S. Battersby, M. R. Millar, P. Brown, and R. P. Millar Reciprocal Cross Talk between Gonadotropin-Releasing Hormone (GnRH) and Prostaglandin Receptors Regulates GnRH Receptor Expression and Differential Gonadotropin Secretion Mol. Endocrinol., February 1, 2007; 21(2): 524 - 537. [Abstract] [Full Text] [PDF]

				D. W. Waring and J. L. Turgeon Estradiol Inhibition of Voltage-Activated and Gonadotropin-Releasing Hormone-Induced Currents in Mouse Gonadotrophs Endocrinology, December 1, 2006; 147(12): 5798 - 5805. [Abstract] [Full Text] [PDF]

				V. G. Thackray, S. M. McGillivray, and P. L. Mellon Androgens, Progestins, and Glucocorticoids Induce Follicle-Stimulating Hormone {beta}-Subunit Gene Expression at the Level of the Gonadotrope Mol. Endocrinol., September 1, 2006; 20(9): 2062 - 2079. [Abstract] [Full Text] [PDF]

				H. Zhou, X. Wang, W. K. W. Ko, and A. O. L. Wong Evidence for a Novel Intrapituitary Autocrine/Paracrine Feedback Loop Regulating Growth Hormone Synthesis and Secretion in Grass Carp Pituitary Cells by Functional Interactions between Gonadotrophs and Somatotrophs Endocrinology, December 1, 2004; 145(12): 5548 - 5559. [Abstract] [Full Text] [PDF]

				J. W. Hill, J. H. Urban, M. Xu, and J. E. Levine Estrogen Induces Neuropeptide Y (NPY) Y1 Receptor Gene Expression and Responsiveness to NPY in Gonadotrope-Enriched Pituitary Cell Cultures Endocrinology, May 1, 2004; 145(5): 2283 - 2290. [Abstract] [Full Text] [PDF]

				T. J. Spady, R. Shayya, V. G. Thackray, L. Ehrensberger, J. S. Bailey, and P. L. Mellon Androgen Regulates Follicle-Stimulating Hormone {beta} Gene Expression in an Activin-Dependent Manner in Immortalized Gonadotropes Mol. Endocrinol., April 1, 2004; 18(4): 925 - 940. [Abstract] [Full Text] [PDF]

				Y. Yamada, H. Yamamoto, T. Yonehara, H. Kanasaki, H. Nakanishi, E. Miyamoto, and K. Miyazaki Differential Activation of the Luteinizing Hormone {beta}-Subunit Promoter by Activin and Gonadotropin-Releasing Hormone: A Role for the Mitogen-Activated Protein Kinase Signaling Pathway in L{beta}T2 Gonadotrophs Biol Reprod, January 1, 2004; 70(1): 236 - 243. [Abstract] [Full Text] [PDF]

				J. L. Turgeon, G. Shyamala, and D. W. Waring PR Localization and Anterior Pituitary Cell Populations in Vitro in Ovariectomized Wild-Type and PR-Knockout Mice Endocrinology, October 1, 2001; 142(10): 4479 - 4485. [Abstract] [Full Text] [PDF]

				G. V. Childs, G. Unabia, and P. Wu Differential Expression of Growth Hormone Messenger Ribonucleic Acid by Somatotropes and Gonadotropes in Male and Cycling Female Rats Endocrinology, April 1, 2000; 141(4): 1560 - 1570. [Abstract] [Full Text] [PDF]

				J. L. Turgeon, S. M. Van Patten, G. Shyamala, and D. W. Waring Steroid Regulation of Progesterone Receptor Expression in Cultured Rat Gonadotropes Endocrinology, May 1, 1999; 140(5): 2318 - 2325. [Abstract] [Full Text]

				J. H. Stahl, S. K. Kendall, M. L. Brinkmeier, T. L. Greco, D. E. Watkins-Chow, A. Campos-Barros, R. V. Lloyd, and S. A. Camper Thyroid Hormone Is Essential for Pituitary Somatotropes and Lactotropes Endocrinology, April 1, 1999; 140(4): 1884 - 1892. [Abstract] [Full Text]

				T. Watanabe, T. Banno, T. Jeziorowski, Y. Ohsawa, S. Waguri, D. Grube, and Y. Uchiyama Effects of Sex Steroids on Secretory Granule Formation in Gonadotropes of Castrated Male Rats with Respect to Granin Expression Endocrinology, June 1, 1998; 139(6): 2765 - 2773. [Abstract] [Full Text] [PDF]

				B. D. Saunders, E. Sabbagh, W. W. Chin, and U. B. Kaiser Differential Use of Signal Transduction Pathways in the Gonadotropin-Releasing Hormone-Mediated Regulation of Gonadotropin Subunit Gene Expression Endocrinology, April 1, 1998; 139(4): 1835 - 1843. [Abstract] [Full Text] [PDF]

				J. D. Kirby, N. Arambepola, T. Porkka-Heiskanen, Y. K. Kirby, M. L. Rhoads, H. Nitta, A. E. Jetton, G. Iwamoto, G. L. Jackson, F. W. Turek, et al. Neonatal Hypothyroidism Permanently Alters Follicle-Stimulating Hormone and Luteinizing Hormone Production in the Male Rat Endocrinology, July 1, 1997; 138(7): 2713 - 2721. [Abstract] [Full Text] [PDF]

				U. B. Kaiser, P. M. Conn, and W. W. Chin Studies of Gonadotropin-Releasing Hormone (GnRH) Action Using GnRH Receptor-Expressing Pituitary Cell Lines Endocr. Rev., February 1, 1997; 18(1): 46 - 70. [Abstract] [Full Text]

				S K Kendall, L C Samuelson, T L Saunders, R I Wood, and S A Camper Targeted disruption of the pituitary glycoprotein hormone alpha-subunit produces hypogonadal and hypothyroid mice. Genes & Dev., August 15, 1995; 9(16): 2007 - 2019. [Abstract] [PDF]