The research proposed here addresses internal and external regulators of sexual maturation in vertebrates. Specifically, development of forebrain magnocellular neurons immunoreactive to gonadotropon-releasing hormone (irGnRH) are to be studied in a teleost using cellular and molecular probes. Forebrain irGnRH neurons comprise a phylogenetically ancient system which plays a central role in modulating pituitary control of gonadal maturation in all vertebrate classes. While analysis of this system in mammals is complicated by the superimposition of neocortical functions, basal forebrain organization can be readily studied in teleosts. The irGnRh neurons and their modulation of pituitary function have important consequences to the organism and are often implicated in growth or maturation related disease (hypogonadism and juvenilized physiolgnomy). In the teleost, H. burtoni, both development of irGnRH neurons as measured by some size and complexity of neurite morphology, and gonadal maturation are influenced by social interactions. Competition form larger conspecifics suppresses maturation in young adult fish, causing both undersized irGnRH forebrain neurons and hypogonadism. Since we can control the social system, this system is highly advantageous for analysis of maturation. Two classes of experiments are proposed: One to identify the sensory modality which is responsible for mediating social signals which suppress maturation and the second to ablate two key systems, olfactory bulb and gonads, implicated in forebrain maturation. We will measure the consequences of these experiments with immunoreactivity to GnRH antibody and molecular probes to the mRNA of GnRH. We will thus be able to discover the cellular and molecular consequences of social regulation of maturation. Since the results of social interaction are quite extreme. This may set the stage for understanding a pathway for the social regulation of gene action.

Agency
National Institute of Health (NIH)
Institute
Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD)
Type
Research Project (R01)
Project #
1R01HD023799-01A1
Application #
3324075
Study Section
Neurology B Subcommittee 1 (NEUB)
Project Start
1989-08-01
Project End
1994-04-30
Budget Start
1989-08-01
Budget End
1990-04-30
Support Year
1
Fiscal Year
1989
Total Cost
Indirect Cost
Name
University of Oregon
Department
Type
Graduate Schools
DUNS #
948117312
City
Eugene
State
OR
Country
United States
Zip Code
97403
Winberg, S; Winberg, Y; Fernald, R D (1997) Effect of social rank on brain monoaminergic activity in a cichlid fish. Brain Behav Evol 49:230-6
Soma, K K; Francis, R C; Wingfield, J C et al. (1996) Androgen regulation of hypothalamic neurons containing gonadotropin-releasing hormone in a cichlid fish: integration with social cues. Horm Behav 30:216-26
Kasten, T L; White, S A; Norton, T T et al. (1996) Characterization of two new preproGnRH mRNAs in the tree shrew: first direct evidence for mesencephalic GnRH gene expression in a placental mammal. Gen Comp Endocrinol 104:7-19
White, S A; Kasten, T L; Bond, C T et al. (1995) Three gonadotropin-releasing hormone genes in one organism suggest novel roles for an ancient peptide. Proc Natl Acad Sci U S A 92:8363-7
Bushnik, T L; Fernald, R D (1995) The population of GnRH-containing neurons showing socially mediated size changes project to the pituitary in a teleost, Haplochromis burtoni. Brain Behav Evol 46:371-7
Fernald, R D (1995) Social control of cell size: males and females are different. Prog Brain Res 105:171-7
Francis, R C; Lee, H N; Fernald, R D (1994) Ontogeny of gonadotropin releasing hormone-containing neurons in the teleost brain. Brain Res Dev Brain Res 78:151-60
White, S A; Bond, C T; Francis, R C et al. (1994) A second gene for gonadotropin-releasing hormone: cDNA and expression pattern in the brain. Proc Natl Acad Sci U S A 91:1423-7
White, S A; Fernald, R D (1993) Gonadotropin-releasing hormone-containing neurons change size with reproductive state in female Haplochromis burtoni. J Neurosci 13:434-41
Francis, R C; Soma, K; Fernald, R D (1993) Social regulation of the brain-pituitary-gonadal axis. Proc Natl Acad Sci U S A 90:7794-8

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