International Mammalian Genome Society

The 16th International Mouse Genome Conference (2002)


Oral Presentation

Wednesday 20 November

16:00 - 16:15 HRS

A NOVEL MOUSE MODEL OF HYPOGONADISM

RR Behringer
M. D. Anderson Cancer Center

Co-Authors: 1) Pask AJ, 1) Wang Y, 2) Salinger AP, 2) Justice MJ
Institutions: 1) MD Anderson Cancer Center, 2) Baylor College of Medicine

An autosomal recessive mutation that affects sexual differentiation and fertility was isolated in an ENU mutagenesis screen for developmental defects. Affected males were initially identified at weaning because they had a small genital papilla and shortened genito-anal distance relative to controls. In addition, affected males had small, cryptorchid testes, poor Wolffian duct differentiation, and an arrest at the early to mid-pachytene stage of spermatogenesis. Female mutants had a thin uterus and small ovaries with fewer follicles that were arrested at the 2o follicle stage of oogenesis. These hypogonadal mutant mice had dramatically reduced levels of circulating follicle stimulating hormone (FSH) and luteinizing hormone (LH). In addition, the number of immunopositive FSH and LH cells in mutant pituitaries was significantly reduced. The hypogonadal (hpg) mutation located on mouse chromosome 14 (39 cM) causes recessive hypogonadism. The mutated gene encodes the gonadotropin-releasing hormone (GnRH) that is expressed in hypothalamic neurons to stimulate pituitary FSH and LH secretion. This signal is mediated by the GnRH receptor, a G-protein coupled seven-transmembrane receptor encoded by the gnrhr gene located on mouse chromosome 5 (44 cM). GnRHR mutations in humans cause hypogonadism. However, there are no mouse mutants for gnrhr. Using a pooled mapping strategy, we have mapped our ENU-induced mutation to chromosome 5 (44 cM), indicating that we have isolated a mutation in gnrhr. These mice should serve as a novel resource for studying developmental defects in sexual differentiation and fertility.


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