What are these so-called hypocretin (orexin) molecules?
Hypocretins (orexins) were discovered by two groups of researchers almost simultaneously, hence the two names “hypocretins” and “orexins”. The first group called them “hypocretin-1” and “hypocretin-2” after discovering that the molecules were found only in the hypothalamus and had some weak resemblance with the gut hormone secretin. Only 10,000-20,000 cells in the entire human brain (out of many billions) secrete these specific hypocretin molecules. The hypothalamus, a region localized deep in the base of the brain, regulates many basic functions such as the release of hormones, blood pressure, sex, food intake regulation and sleep. The subregion of the hypothalamus containing the hypocretin cells was known to be especially important for the regulation of feeding. These molecules were thus first hypothesized to be important in feeding regulation. In fact, the second group that discovered the hypocretin molecules called them “orexin A and orexin B” (from orexis=appetite in grec) and sug
