The long-term objectives of this research is to improve the present understanding of the hormonal control of male reproductive functions by elucidating the effects of prolactin (PRL) on the testes and the hypothalamic-pituitary system. Benefits from this project will include obtaining new information on the control of endocrine and reproductive functions in health and disease. One of the specific aims for the next five years will be to define hormonal control of testicular PRL receptors before and after sexual maturation and to relate the PRL-induced changes in the levels of LH and PRL receptors to the ability of the testis to respond to LH and PRL stimulation.
Other aims of this project will be to elucidate the mechanisms responsible for the effects of PRL on the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from the anterior pituitary. The proposed studies will involve measurements of binding of radioactively labelled hormones to testicular membrane preparations, measurements of blood levels of pituitary and testicular hormones, assessment of noradrenergic, dopaminergic and serotonergic transmission in the hypothalamus by measurement of levels, turnover rates and metabolites of neurotransmitters in different brain regions, determinations of luteinizing hormone releasing hormone (LHR) stores in the hypothalamus and studying the control of its release in vivo and in vitro, as well as measurements of pituitary LHRH receptors and pituitary responsiveness to LHRH stimulation. Most of the proposed studies will be conducted in golden hamsters because in this species, PRL has already been shown to exert major and physiologically important effects on male reproductive functions, and PRL release can be readily manipulated by environmental lighting conditions without pharmacologic or surgical intervention. However, in order to more readily identify cause-effect relationships between the various effects of PRL and to determine whether our findings may apply to other mammalian species, we will conduct parallel comparative studies in the rat, the mouse and the Djungarian hamster.

Agency
National Institute of Health (NIH)
Institute
Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD)
Type
Research Project (R01)
Project #
5R01HD020033-06
Application #
3317822
Study Section
Reproductive Biology Study Section (REB)
Project Start
1984-08-01
Project End
1991-07-31
Budget Start
1989-08-01
Budget End
1990-07-31
Support Year
6
Fiscal Year
1989
Total Cost
Indirect Cost
Name
Southern Illinois University Carbondale
Department
Type
Schools of Arts and Sciences
DUNS #
939007555
City
Carbondale
State
IL
Country
United States
Zip Code
62901
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Vidal, S; Stefaneanu, L; Kovacs, K et al. (1999) Pituitary estrogen receptor alpha and dopamine subtype 2 receptor gene expression in transgenic mice with overproduction of heterologous growth hormones. Histochem Cell Biol 111:235-41
Debeljuk, L; Wright, J C; Phelps, C et al. (1999) Transgenic mice overexpressing the growth-hormone-releasing hormone gene have high concentrations of tachykinins in the anterior pituitary gland. Neuroendocrinology 70:107-16
Dominici, F P; Cifone, D; Bartke, A et al. (1999) Alterations in the early steps of the insulin-signaling system in skeletal muscle of GH-transgenic mice. Am J Physiol 277:E447-54

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