Social cues from conspecifics alter electrical activity of gonadotropin-releasing hormone neurons in the terminal nerve via visual signals

• Published in: American journal of physiology. Regulatory, integrative and comparative physiology Vol. 297; no. 1; pp. R135 - R141
• Main Authors: Ramakrishnan, Siddharth, Wayne, Nancy L
• Format: Journal Article
• Language: English
• Published: United States American Physiological Society 01.07.2009
• Subjects: Action Potentials; Animals; Animals, Genetically Modified; Behavior, Animal; Brain; Cues; Female; Fish; Fish Proteins - genetics; Fish Proteins - metabolism; Gonadotropin-Releasing Hormone - genetics; Gonadotropin-Releasing Hormone - metabolism; Green Fluorescent Proteins - genetics; Green Fluorescent Proteins - metabolism; Hormones; Male; Neural Inhibition; Neural Pathways - metabolism; Neurons; Neurons - metabolism; Olfactory Bulb - metabolism; Oryzias; Patch-Clamp Techniques; Photic Stimulation; Promoter Regions, Genetic; Pyrrolidonecarboxylic Acid - analogs & derivatives; Sensory perception; Social Behavior; Stimulation, Chemical; Studies
• ISSN: 0363-6119; 1522-1490
• DOI: 10.1152/ajpregu.00143.2009

Department of Physiology, David Geffen School of Medicine at the University of California at Los Angeles, Los Angeles, California Submitted 10 March 2009 ; accepted in final form 1 May 2009 There are multiple populations of gonadotropin-releasing hormone (GnRH) neurons in the brains of vertebrates. The population located in the hypothalamus/preoptic area is the best studied and is known to ultimately control reproduction. Teleost fish have an additional population of GnRH neurons in the terminal nerve (TN) associated with the olfactory bulbs, the physiological function of which is still unclear. Anatomical and physiological studies provide evidence that TN-GnRH neurons have extensive projections in the brain and modulate neuronal activity. Although there is anatomical evidence that the TN receives olfactory and optic sensory inputs, it is not known if sensory information is transmitted to TN-GnRH neurons to modulate their activity. In the present study, we tested the hypothesis that social cues from conspecifics modulate electrical activity of TN-GnRH neurons from the intact brain of female medaka fish ( Oryzias latipes ). We further investigated the potential roles of chemosensory and visual signals in mediating the social cue response. We used a transgenic line of medaka with TN-GnRH neurons genetically tagged with green fluorescent protein, allowing visualization of specific neurons for whole-cell current clamp electrophysiology. We demonstrated that 24-h exposure to male visual and chemosensory cues suppressed the electrical activity of female TN-GnRH neurons compared with exposure to other females. Chemosensory cues alone were insufficient to induce this social cue response. However, visual cues alone replicated the "combined" social cue response. These findings support our hypothesis that sensory signals—and specifically, visual social cues—modulate electrical activity of TN-GnRH neurons. electrophysiology; fish; medaka; neuroendocrine; sensory Address for reprint requests and other correspondence: Correspondence: Nancy L. Wayne, Dept. of Physiology, Rm. 53-231 Center for Health Sciences, David Geffen School of Medicine at the Univ. of California at Los Angeles School, Los Angeles, CA 90095-1751 (e-mail: nwayne{at}mednet.ucla.edu )