Bombesin is a neuropeptide that is commonly found in the human brain and gastrointestinal tract. It plays an important role in regulating a variety of physiological functions, including appetite and energy metabolism. There are several synonyms for bombesin, including gastrin-releasing peptide, neuromedin B, and ranatensin. Gastrin-releasing peptide is a related hormone that is structurally similar to bombesin and is also involved in regulating appetite and energy metabolism. Neuromedin B is another peptide that is closely related to bombesin and has been shown to have similar biological effects. Ranatensin is a peptide that is often used in research as a substitute for bombesin due to its similar structure and function.