Abstract

The neuroendocrine regulation of ovarian cyclicity in a seasonally breeding species is the theme of this project. Studies will be performed to identify signals pertinent to photoperiodic, pineal, hypothalamic and steroidal regulation of pulsatile LH secretion and response to estradiol negative feedback in the female sheep. Particularl emphasis will be placed on the importance of patterning of these signals to generation of responses. The patterns of hypothalamic GnRH and pineal melatonin signals will be of special interest and will be studied using a portable back-pack infusion system. Stereotaxically placed knife-cuts in the hypothalamus and immunocytochemical localization of GnRH in neurons of the sheep brain will be used to examine the neural processing of photoperiodic and steroidal signals which regulate pulsatile LH secretion. Radioimmunoassays will be used to measure serum LH, FSH, GnRH, melatonin, estradiol and progesterone. It is expected that these findings will lead to new insight concerning ovarian cyclicity and seasonal breeding, an natural process of reversable fertility.

  Funding Agency

Agency
National Institute of Health (NIH)
Institute
Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD)
Type
Research Project (R01)
Project #
5R01HD018337-09
Application #
3315378
Study Section
Biochemical Endocrinology Study Section (BCE)
Project Start
1984-03-01
Project End
1994-06-30
Budget Start
1992-07-01
Budget End
1993-06-30
Support Year
9
Fiscal Year
1992
Total Cost
Indirect Cost

  Institution

Name
University of Michigan Ann Arbor
Department
Type
Organized Research Units
DUNS #
791277940
City
Ann Arbor
State
MI
Country
United States
Zip Code
48109

  Publications

Battaglia, D F; Beaver, A B; Harris, T G et al. (1999) Endotoxin disrupts the estradiol-induced luteinizing hormone surge: interference with estradiol signal reading, not surge release. Endocrinology 140:2471-9
Bowen, J M; Dahl, G E; Evans, N P et al. (1998) Importance of the gonadotropin-releasing hormone (GnRH) surge for induction of the preovulatory luteinizing hormone surge of the ewe: dose-response relationship and excess of GnRH. Endocrinology 139:588-95
Battaglia, D F; Brown, M E; Krasa, H B et al. (1998) Systemic challenge with endotoxin stimulates corticotropin-releasing hormone and arginine vasopressin secretion into hypophyseal portal blood: coincidence with gonadotropin-releasing hormone suppression. Endocrinology 139:4175-81
Xiong, J J; Karsch, F J; Lehman, M N (1997) Evidence for seasonal plasticity in the gonadotropin-releasing hormone (GnRH) system of the ewe: changes in synaptic inputs onto GnRH neurons. Endocrinology 138:1240-50
Battaglia, D F; Bowen, J M; Krasa, H B et al. (1997) Endotoxin inhibits the reproductive neuroendocrine axis while stimulating adrenal steroids: a simultaneous view from hypophyseal portal and peripheral blood. Endocrinology 138:4273-81
Karsch, F J; Bowen, J M; Caraty, A et al. (1997) Gonadotropin-releasing hormone requirements for ovulation. Biol Reprod 56:303-9
Evans, N P; Dahl, G E; Padmanabhan, V et al. (1997) Estradiol requirements for induction and maintenance of the gonadotropin-releasing hormone surge: implications for neuroendocrine processing of the estradiol signal. Endocrinology 138:5408-14
Lehman, M N; Goodman, R L; Karsch, F J et al. (1997) The GnRH system of seasonal breeders: anatomy and plasticity. Brain Res Bull 44:445-57
Evans, N P; Dahl, G E; Caraty, A et al. (1996) How much of the gonadotropin-releasing hormone (GnRH) surge is required for generation of the luteinizing hormone surge in the ewe? Duration of the endogenous GnRH signal. Endocrinology 137:4730-7
Karsch, F J; Evans, N P (1996) Feedback actions of estradiol on GnRH secretion during the follicular phase of the estrous cycle. Acta Neurobiol Exp (Wars) 56:715-25

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