This proposed research will continue the studies of subsets of pituitary gonadotropes that secrete luteinizing hormone (LH) and follicle stimulating hormone (FSH). Gonadotropes are diverse when tests of their storage or secretory functions are made and the purpose of the ongoing research is to learn if such diversity can be correlated with a particular functional or maturational state during the estrous cycle. The experiments will be gin by separating small, medium and large gonadotropes with counterflow centrifugation in a new elutriation chamber. The cells will be taken from homogeneous groups of female rats at specific stages of the cycle. The first set of studies will determine if subsets of small gonadotropes release more gonadotropins prior to peak proestrous or estrous secretory activity than large gonadotropes. Secretion (LH or FSH) will be detected by radioimmunoassay or the reverse hemolytic plaque assay (RHPA). The results will be correlated with changes in storage patterns of LHbeta and FSHbeta antigens detected by immunoperoxidase or immunogold protocols, and LHbeta and FSHbeta mRNA detected by in situ hybridization and measured by Northern Blot assays. The second set of studies will determine if and when the small gonadotropes bind a biotinylated analog of gonadotropin releasing hormone (GnRH) and if estradiol enhances GnRH binding. If enhancement is evident, the data would indicate that some small gonadotropes may be precursors to the large gonadotropes. The third set of studies will compare the responses of small and large gonadotropes to activation of second messengers, to learn if small gonadotropes change their capacity to respond during the estrous cycle. Responses to be analyzed include LH and FSH secretion, LHbeta or FSHbeta subunit antigen storage, mRNA expression, and GnRH binding. GnRH receptors,beta subunit antigens or mRNAs will be detected by labeled avidin protocols. Changes in the amount of label will be quantified with image analysis systems that measure color or density. The studies will provide information about individual subsets of gonadotropes that will broaden our understanding of their responses to GnRH and steroids and better define the different cycles of activity expressed by the small and large gonadotropes..

Agency
National Institute of Health (NIH)
Institute
Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD)
Type
Research Project (R01)
Project #
5R01HD015472-10
Application #
3313117
Study Section
Endocrinology Study Section (END)
Project Start
1981-05-01
Project End
1994-08-31
Budget Start
1991-09-01
Budget End
1992-08-31
Support Year
10
Fiscal Year
1991
Total Cost
Indirect Cost
Name
University of Texas Medical Br Galveston
Department
Type
Schools of Medicine
DUNS #
041367053
City
Galveston
State
TX
Country
United States
Zip Code
77555
Childs, G V (2000) Growth hormone cells as co-gonadotropes: partners in the regulation of the reproductive system. Trends Endocrinol Metab 11:168-75
Childs, G V; Unabia, G; Miller, B T et al. (1999) Differential expression of gonadotropin and prolactin antigens by GHRH target cells from male and female rats. J Endocrinol 162:177-87
Childs, G V (1997) Cytochemical studies of multifunctional gonadotropes. Microsc Res Tech 39:114-30
Childs, G V; Miller, B T; Miller, W L (1997) Differential effects of inhibin on gonadotropin stores and gonadotropin-releasing hormone binding to pituitary cells from cycling female rats. Endocrinology 138:1577-84
Armstrong, J; Childs, G V (1997) Changes in expression of epidermal growth factor receptors by anterior pituitary cells during the estrous cycle: cyclic expression by gonadotropes. Endocrinology 138:1903-8
Armstrong, J; Childs, G V (1997) Differential expression of c-fos in vitro by all anterior pituitary cell types during the estrous cycle: enhanced expression by luteinizing hormone but not by follicle-stimulating hormone cells. J Histochem Cytochem 45:785-94
Ghosh, B R; Wu, J C; Strahl, B D et al. (1996) Inhibin and estradiol alter gonadotropes differentially in ovine pituitary cultures: changing gonadotrope numbers and calcium responses to gonadotropin-releasing hormone. Endocrinology 137:5144-54
Childs, G V (1995) Division of labor among gonadotropes. Vitam Horm 50:215-86
Childs, G V; Unabia, G; Miller, B T (1994) Cytochemical detection of gonadotropin-releasing hormone-binding sites on rat pituitary cells with luteinizing hormone, follicle-stimulating hormone, and growth hormone antigens during diestrous up-regulation. Endocrinology 134:1943-51
Childs, G V; Unabia, G; Rougeau, D (1994) Cells that express luteinizing hormone (LH) and follicle-stimulating hormone (FSH) beta-subunit messenger ribonucleic acids during the estrous cycle: the major contributors contain LH beta, FSH beta, and/or growth hormone. Endocrinology 134:990-7

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