Category Nuances for enkephalin:

• nervous,
• analgesic,
• important,
• useful,
• active,
• endogenous,
• proinflammatory,
• physiological,
• psychoactive,
• natural,
• common,

Simple Categories for enkephalin:

• compound,
• system,
• substrate,
• peptide,
• substance,
• polypeptide,