scotophobin

[skoh-tuh-foh-bin]
noun
  1. a peptide isolated from the brains of rats conditioned to avoid darkness, alleged to induce a dark-avoidance response in untrained rats, mice, and other animals.
Related formssco·to·pho·bic, adjective
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018