Upping the ante – some fish make their cells more sensitive within minutes of a social encounter by inserting ion channels into the cell membrane. Hormones released into circulation by the pituitary evoke the effect. What has this got to do with us? Well, if you have been to one of the Explain Pain seminars lately you will be sick of Lorimer telling you that one way in which the spinal nociceptor adapts to ongoing activity (ie central sensitisation) is by inserting new chemically-driven ion channels into the cell membrane. In fish, this kind of process can clearly happen quickly and is reversible. I wonder if this has implications for our understanding of sensitisation, or, perhaps, for our understanding of social interactions or the role of hormones in central sensitisation, or…… 
Sternopygus macrurus image from the Bolton Museum
Circadian and Social Cues Regulate Ion Channel Trafficking
Michael R. Markham(a,b,c), M. Lynne McAnelly(a,b), Philip K. Stoddard(c), Harold H. Zakon(a,b)
(a) Section of Neurobiology, Patterson Laboratory, The University of Texas at Austin, Austin, Texas, United States of America,
(b) Institute for Neuroscience, Patterson Laboratory, The University of Texas at Austin, Austin, Texas, United States of America,
(c) Department of Biological Sciences, Florida International University, Miami, Florida, United States of America
Abstract
Electric fish generate and sense electric fields for navigation and communication. These signals can be energetically costly to produce and can attract electroreceptive predators. To minimize costs, some nocturnally active electric fish rapidly boost the power of their signals only at times of high social activity, either as night approaches or in response to social encounters. Here we show that the gymnotiform electric fish Sternopygus macrurus rapidly boosts signal amplitude by 40% at night and during social encounters. S. macrurus increases signal magnitude through the rapid and selective trafficking of voltage-gated sodium channels into the excitable membranes of its electrogenic cells, a process under the control of pituitary peptide hormones and intracellular second-messenger pathways. S. macrurus thus maintains a circadian rhythm in signal amplitude and adapts within minutes to environmental events by increasing signal amplitude through the rapid trafficking of ion channels, a process that directly modifies an ongoing behavior in real time.
See full article at PLoS Biology PLoS Biol 7(9): e1000203.