The origin and destiny of cholesterol in the animal organism. Part I. -On the so-called hippocoprosterol

Abstract

Since the discovery of cholesterol by Conradi in 1755, and its analysis by Chevreul in 1815, it has been found to be very widely distributed in the animal and in isomeric forms in the vegetable kingdom. It is found in small oily excretions of the skin, and is an especially abundant constituent of the white substance of brain and of the medullary sheath of nerve. But, although a considerable amount of work has been done, we have little or no definite knowledge of its physiological functions, and it is only in very recent times that a small glimmering of light has been thrown on its chemical constitution. In 1862, Austin Flint published a series of experiments by which he attempted to show that cholesterol is always more abundant in the blood coming from the brain than in the blood of the general arterial system, or in the venous blood from other parts; that its quantity is hardly appreciable in venous blood from the paralysed side in hemiplegia, and that it is separated from the blood by the liver. He also stated that in cases of serious structural disease of the liver, accompanied by symptoms pointing to blood poisoning, cholesterol accumulates in the blood, constituting a condition which he named cholesteræmia. From his experiments he came to the conclusion that cholesterol is a product of the metabolism of nervous tissues, that it carried from the brain by means of the blood and excreted by the liver through the bile, and, finally, that “we know of no function which it has to perform in the economy, any more than urea or any other of the excrementitious principles of the urine.” Flint’s methods of analysis were, however, open to grave objection, and he draws sweeping conclusions from of considerable accuracy, we should have hesitated to attribute much significance to the figures. Flint also observed that the cholesterol of the bile undergoes a modification in the intestine, and is found in the fæces as “stercorine”. Some support was lent to Flint’s views by the experiments of Picot in 1872 and Koloman Müller in 1873. Picot reported a fatal case of “grave jaundice”, in which he found a great increase in the proportion of cholesterol in the blood; and Müller injected into the veins of dogs 2.16 fluid ounces of s solution containing 69 grains of cholesterol, made by rubbing cholesterol with glycerine and mixing the mass with soap and water. In five experiments of this kind, he produced a complete representation of the phenomena of “grave jaundice”.