Meeting Abstract

S6-1.5  Saturday, Jan. 5  GnRH Peptides and Receptors: The Strange Twists of Evolution SHERWOOD, N.M.; TELLO, J.A.; WU, S.; ADAMS, B.A.; University of Victoria, B.C., Canada; University of Victoria, B.C., Canada; University of Victoria, B.C., Canada; University of Victoria, B.C., Canada

Gonadotropin-releasing hormone (GnRH) is a small neuropeptide that initiates a cascade of events resulting in the release of gametes and sex steroids from the gonads. Novel forms of GnRH have been identified by protein chemistry in many vertebrate species establishing a fundamental pattern for vertebrate control of reproduction. With the advent of molecular biology, the organization of GnRH genes was established for a number of GnRH peptides in vertebrates. In addition, GnRH receptors were cloned for most vertebrate classes establishing that the target organs for GnRH extend far beyond the pituitary. Now, genomics has provided the DNA database to examine reproduction in animals that evolved before the vertebrates: sea squirts and amphioxus. A new ancestral pattern is evident in which reproduction can occur without the classical pituitary hormones and in some cases without the sex steroids and their receptors, but always with GnRH and its receptors. And yet evolution has resulted in a reduction in the number of GnRH peptides and receptors from six GnRH peptides and three functioning receptors in sea squirt to two peptides and 4 receptors in zebra fish but only one of each in mouse. Post-genomic analysis of GnRH functions after knock down of the GnRH mRNAs in zebra fish or disruption of the single GnRH receptor with a gene trap method in mice show a wide range of novel functions even in a monolithic system.