Gonadotropin-releasing hormone signaling in behavioral plasticity.

Sex and reproduction sculpt brain and behavior throughout life and evolution. In vertebrates, gonadotropin-releasing hormone (GnRH) is essential to these processes. Recent advances have uncovered novel regulatory mechanisms in GnRH signaling, such as the initiation of sexual maturation by kisspeptins. Yet despite our increasing molecular knowledge, we know very little about environmental influences on GnRH signaling and reproductive behavior. Alternative model systems have been crucial for understanding the plasticity of GnRH effects within an organismal context. For instance, GnRH signaling is under the control of seasonal cues in songbirds, whereas social signals regulate GnRH in cichlid fishes, with crucial consequences for reproduction and behavior. Analyzing cellular signaling cascades within an organismic context is essential for an integrative understanding of GnRH function.