Prolactin

In 1929 Scientist Karl Ehrhardt of Germany published photographs of a female monkey holding a young guinea pig in a maternal manner. This foster mother had been injected with a crude extract from pituitary glands. In 1932 Dr. Oscar Riddle and his associates at the Carnegie Institution's station for experimental evolution on Long Island obtained in almost pure form the same pituitary substance which had made Ehrhardt's monkey act like a mother. Because it was a stimulant of milk secretion this substance was called prolactin.

Prolactin was found to induce mammary activity in virgin and castrated female and even in male animals; it induced parental behavior in birds and rats; it increased the basal metabolism (heat production) ; it seemed to affect carbohydrate metabolism through the adrenal glands; it caused growth of liver and intestines; it increased the blood's sugar content; and it inhibited the sex glands, causing pigeons' ovaries to stop producing ova and to reabsorb those already formed, and the testes of males to shrink. This last effect, in Dr. Riddle's opinion, was exerted indirectly--by blocking release of the pituitary substance which normally stimulates sex activity. It seemed to show that parental behavior and sex activity are antipathetic, by glandular decree.

Dr. Riddle recently pointed out that no one could be sure which hormones or how many are secreted by the pituitary gland. So long as there was a possibility that his prolactin, no matter how highly concentrated, contained traces of other hormones, he could not be sure whether he was dealing with one substance or several. Dr.

Riddle admitted that the question was open until prolactin was completely purified.

Last week at the American Chemical Society's convention in Dallas, Dr. Abraham White. 30-year-old professor of physiological chemistry at Yale University, announced that he had done the trick: extracted prolactin in the form of chemically pure crystals. His first physiological tests of the crystalline hormone seemed to show that it was simply a milk-secreting stimulus. He got no growth response of the abdominal organs, no increase of blood sugar. Other tests for the Riddle reactions were in progress when he made his report. In Cold Spring Harbor last week, Dr. Riddle said he had received some of Dr. White's crystals, but that he had not yet satisfied himself that they were pure prolactin.

Dr. White found that his crystal was a heavy protein. In a way, this was unfortunate. In no case has the structural formula, or atomic architecture, of any protein molecule been mapped out by biochemists. It has been calculated that if a typical protein consists of 30 amino acids (protein structural units), 18 of which are different, the number of possible molecular arrangements is about 1,000,000,000,000,000,000,000,000,000. Young Dr. White made the point that the mystery of protein structure must be cleared up before scientists can understand how the hormones exert their obscure, powerful control on living processes. The chemists applauded his paper heartily and he was awarded the $1,000 Eli Lilly & Co. prize for meritorious biochemical research.

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