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.
Cyril Norman Hugh Long
In the 1930s and 1940s Long and Abraham White worked together in the Yale Medical Center. As a result of their work in 1937 they isolated bovine prolactin, the first of the protein pituitary hormones to be obtained in pure crystalline form. Later, they isolated different hormones, and later characterized and sequenced many of them, greatly contributing to modern biochemistry. Long mainly worked with the hormones of the pituitary gland and adrenal extracts of the metabolism; his major research goal was to find a cure for diabetes.