Galanin Expression in the Zebrafish Brain (image) California Institute of Technology Share Print E-Mail Caption Overexpression of the neuropeptide prokineticin 2 (Prok2) results in an increase in expression of the sleep-promoting neuropeptide galanin (shown in white) when zebrafish are kept in the light, but not when they are kept in the dark, compared to wild type control animals. These images show galanin expression in the anterior hypothalamus, a brain region known to promote sleep in mammals. Credit Prober laboratory Usage Restrictions WITH IMAGE CREDITS Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.