- Either of two hormones ( orexin-A or orexin-B) produced by the mammalian hypothalamus and functional in the regulation of appetite and sleep. Also called hypocretin.More example sentences
- For example, physical activity increased in rats when injected with orexin, a brain chemical associated with sexual arousal.
- The lateral hypothalamus contains cells that secrete a protein neurotransmitter called ‘orexin’ or ‘hypocretin.’
- Human narcolepsy generally stems from a shortage of the neurons, which produce the excitatory neurotransmitter known both as hypocretin and orexin.