A.k.a.  Secretagogue Peptides: an agent that promotes the secretion of hormones, neurohormones, chemical neurotransmitters, enzymes, or other molecules synthesized and secreted by cells.

They are shorter segments of proteins secreted by our different organs, i.e.  if a protein X secreted by our anterior pituitary contains 100 amino acids and leads to increased growth hormone production, the Peptide contains only 75 amino acids but results in increased growth hormone secretion as well.