Melanocortins and Pigmentation
It all began in 1916, the story not only for the melanocortins and pigmentation but also for the entire field of pituitary endocrinology. Two independent papers appeared in Science by two young biologists, Philip E. Smith in California (1) and Bennett M. Allen in Kansas (2). They described a way to ablate the pituitary glands of tadpoles without killing the animals, and they observed that the tadpoles so treated were light in color. Soon after these reports it was found that injections of pituitary extracts into tadpoles and frogs would turn them dark (3). Before this apparently simple achievement, it was thought that the pituitary gland was necessary for life. No investigator had been able to destroy or remove that gland from any animal and keep it alive. Ten years later Smith (4), in another major success, reported his procedure for the ablation of the hypophysis in rats. He opened the door for intense research on the role of the pituitary gland in mammalian systems. It should not be a surprise that a change in color of tadpoles marked the beginning of pituitary endocrinology. It was essential that one be able to see and measure a change with visible light. There were no spectrophotometers or other equipment to monitor the metabolic processes that occurred outside the visible range after the destruction or removal of a gland or the injection of extracts from glands into animals.
KeywordsPituitary Gland Primary Biliary Cirrhosis Pigment Cell Anterior Lobe Pituitary Extract
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