The brain chemicals that control what we enjoy
Researchers are trying to understand how orexins influence our appetites, and whether we can use them to treat addiction and obesity, explains Andy Extance
Orexins differ greatly from molecules better known for their role in controlling hunger, the hormones ghrelin and leptin. While ghrelin and leptin circulate through our bodies, orexins are neuropeptides, acting only in our brains. Where ghrelin stimulates hunger and leptin suppresses it, orexins’ influences are more fundamental. Evidence suggests that orexins arouse us. They focus us on interesting opportunities around us, such as eating chocolate sweets, but also taking illegal drugs. Drugs are already harnessing the orexins’ role in arousal. And now, researchers like Brown are seeking to understand and exploit how they affect our behaviours.
Scientists discovered ghrelin, leptin and orexins in the 1990s amid growing concern about obesity. They were enabled by new molecular biological methods involving genetic modification, cloning and protein purification. Right from the orexins’ discovery in 1998, it was clear they had multiple roles.