Prothoracicotropic hormone
Prothoracicotropic hormone (PTTH) was the first insect hormone to be discovered. It was originally described simply as "brain hormone" by early workers such as Stefan Kopeć (1922) and Vincent Wigglesworth (1934), who realized that ligation of the head of immature insects could prevent molting or pupation of the body region excluded from the head if the ligation was performed before a critical age in the lifestage was reached. After a certain point the ligation had no effect and both sections of the insect would molt or pupate. However, implantation of a conspecific brain to a sessile ligated abdomen or an abdomen under diapause would induce molting or pupation. Thus, the brain was originally thought to be the source of the hormone that induces molting in insects.
Donald F. Steiner
Donald F. Steiner is known for his discoveries on proinsulin, the precursor of insulin which is a hormone that helps the body control the use of sugar. He found that insulin is synthesized from a larger precursor protein in the beta cells of the pancreas and this led the way to elucidation of how the islet cells function, and how peptide hormones are synthesized and metabolized. He and his colleagues discovered some of the enzymes that convert proinsulin into insulin, and also devised methods for measuring insulin and its precursors in human serum.