The effect of proteins in the prevention of dietary fatty livers

Abstract

RATS fed on low protein diets of high fat content with or without small amounts of cholesterol develop intensely fatty livers; when caseinogen is used as the dietary protein, the degree of fat infiltration diminishes on increasing the amount of this protein present in the diet, irrespective of any action of choline [Channon & Wilkinson, 1935; Beeston et al. 1935]. Further work has shown that a daily intake of 1 g. caseinogen has an effect equivalent to that of 7-8 mg. choline [Beeston & Channon, 1935; Beeston et al. 1936]. Best et al. [1936] obtained similar results regarding this extensive action of caseinogen on liver fat deposition in preventive experiments. While we are continuing our studies of the action of pure amino-acids as one method of elucidating the mechanism of this action of caseinogen [Beeston & Channon, 1936; Channon et al. 1938], information as to the relative lipotropic actions of other proteins is desirable for two reasons. Firstly, it would enable the intensity of action of different proteins to be studied in relation to their amino-acid composition, and perhaps provide evidence of value from this point of view; secondly, it is important to determine which proteins are most satisfactory from the experimental point of view. Diets low in protein tend to cause weight losses even in the short term studies often used in this type of work, and a balance has to be struck between the desirable high fat percentage in the liver and ensuing weight losses. The work described in this paper is, therefore, a study of the actions of a number of plant and animal proteins in preventing fat deposition in the liver, caseinogen being used as the standard. EXPERIMENTAL Preparation of the proteins Edestin was crystallized from 5 % NaCl extracts of hempseed, washed twice with water, twice with alcohol and with ether; the dried powder was extracted twice with hot alcobol and with ether. Yield 75-80 g./kg. hempseed. Fibrin obtained from the slaughterhouse was water-washed until colourless, and dried in alcohol; the powdered product was extracted with water, cold alcohol, hot alcohol and finally with ether. Gliadin. Repeated extraction with 73 % alcohol (3, 3 and 2 1.) of wheat gluten flour (1 kg.), concentration in vacuo of the extracts and cooling in the refrigerator gave a jelly of gliadin, which was dehydrated by successive treatments with acetone; the finely ground product was extracted with cold absolute alcohol and with ether. Yield 275-290 g./kg. gluten flour. Zein. Maize gluten meal (1 kg.) was extracted repeatedly with hot 80 % alcohol (4, 2 and 2 1.), the extract concentrated to 2-5 1., and mixed with 2-5 1. of ether. The gelatinous precipitate was dissolved in warm 90 % alcohol and (976)

Choline as a Dietary Factor

“…Channon and his collaborators (38) have studied the lipotropic activities of a number of plant and animal proteins on the "fat" and "cholesterol" fatty liver using casein as a standard. They found that commercial albumin increased the fat content of liver more than casein when fed at levels of 14 per cent or less, but when increased above this level a marked lipotropic action similar to that of casein was noted.…”

The action of amino-acids and proteins on liver-fat deposition

“…The basal diets used to produce fator cholesterol-fatty livers varied in detail in the different experiments and are mentioned as each is described. Bloodfibrin was prepared according to the method of Channon, Loach, Loizides, Manifold & Soliman [1938a].…”

“…An additional group received 10 % gelatin also supplemented to bring the intake of the 'active' amino-acids to the same level as that of the caseinogen group. A further group received blood fibrin, since it was desirable to obtain more information regarding the action of this protein than had previously been obtained [Channon et al 1938a].…”

47. Kwashiorkor Type of Fatty Liver in Primates

“…Shortly after the lipotropic action of choline and betaine had been established (5), an effect of dietary protein on this phenomenon was noted (6)(7)(8)(9). This led to the discovery that methionine possesses a strong lipotropic activity (i0), which appeared at first to account for the effects of dietary protein (11,12).…”