hypocretin« Back to Glossary Index
Hypocretin, also known as orexin, is a neurotransmitter that regulates alertness, mood, and appetite. Hypocretin/orexin was discovered almost at the same time by two different groups of researchers in the late 1990s. One of the groups, headed by Dr. Masashi Yanagisawa at the University of Texas Southwestern in Dallas, was working on obesity and named the neurotransmitter orexin (orexis is Greek for appetite). The other group, based at Harvard, named it hypocretin, because it is produced in the hypothalamus and somewhat resembles secretin, a hormone found in the gut. For now, the naming controversy continues — both camps are firmly entrenched in their terminology and neither will budge. Whatever its name, high levels of this neurotransmitter are associated with increased appetite, improved mood, and enhanced wakefulness. Low or nonexistent levels of hypocretin are found in the cerebrospinal fluid of people with type 1 narcolepsy.