👉 Histamine is a neurotransmitter that plays a crucial role in the immune system, particularly during inflammation. It is known as an immunomodulator because it can influence the body's response to various threats and diseases. Histamine helps the immune system to fight off infections and protect against allergic reactions. The term "histaminergic" refers to the fact that histamine acts as a neurotransmitter in the central nervous system, specifically in the brain. This means that histamine is involved in regulating the