Scotophobin

Scotophobin (from Ancient Greek σκότος (skótos) 'darkness' and φόβος (phóbos) 'fear') is a peptide discovered by neuroscientist Georges Ungar in 1965[2]: 1  and reported in 1968.

The results of Ungar and his collaborators seemed to show that scotophobin induces fear of the dark in various mammals and fish.

[3] It was discovered in the brain of laboratory rats conditioned to have a fear of darkness.

After a prolonged training, an extract was prepared from their brains, which was injected into mice which were tested in the same lighted/dark setup.

By measuring time spent by the mice in the boxes, it was found that the mice injected with an extract from the treated rats could be distinguished from the ones injected with the extract from the untreated rats.