The Utilization of Fatty Oils Given Parenterally

Abstract

Cod Liver Oil Injections.—Both vitamins A and D in cod liver oil can be utilized by young rats when the oil is administered parenterally. That the oil when so given has toxic properties is evident from the marked deterioration of the physical condition of all animals used, and from the definite increases in nitrogen losses resulting in the dog. The body cells treat the injected oil or its emulsion as they would any irritating foreign substance,—through the protective reticulo-endothelial system. Not all of the oil administered parenterally to rats could be recovered by the extraction method used,—whether the animals were killed in a comparatively good state of nutrition or died of starvation. Some of the oil may have been transported by way of the lymph and excreted in urine or feces or it may have been used as a source of energy; or the extraction method may have been inadequate. The evidence seems generally to indicate that this oil is probably of little or no value nutritively when so given. There was always an abundance of deep yellow encapsulated cod liver oil present in the bodies of the rats at death. Sudan III separates from cod liver oil in which it is dissolved very soon after the mixture is injected. The dye is rapidly excreted by way of the sebaceous glands and the oil particles are promptly engulfed by the endothelial or giant cells and stored in this encapsulated form in the lymphatic system. Butter Oil Injections.—Unquestionably young rats deprived of vitamin A receive protection against the effects of this dietary deficiency or can be cured of existing symptoms by the parenteral administration of butter oil. None of the animals used showed any local or general physical reaction to the injected oil. In most of the autopsies of animals that had received intraperitoneal injections of butter oil there was considerable free oil present at death, with only a relatively small proportion encapsulated. It is apparently only mildly irritating. When Sudan III is dissolved in the oil before injection into adult rats, the dye remains in solution and is only very gradually excreted by way of the sebaceous glands. In these animals free oil could always be recovered from the body after death and this oil had a deep red color, while the encapsulated oil was orange in color. Very little butter oil could be extracted from the bodies of the young rats used in series A experiments, but there was little or no evidence of its utilization by adult rats in the experiments of series C and D. Starvation seemed to have little influence in forcing the utilization of butter oil in mature animals. Butter oil, in the amounts used and under the experimental conditions described, had no effect as a nitrogen-sparing agent. All of the oil injected subcutaneously into the dog had disappeared however, before autopsy, which indicates that perhaps it has been gradually metabolized. Cocoanut Oil Injections.—Practically all the cocoanut oil that was injected into adult rats in series D experiments in which the animals were subsequently starved, had disappeared by the time the animals were autopsied. If, however, the rats were kept in a good state of nutrition following the injections a great deal of oil could be recovered (Series C experiments). Sudan III remained in solution in this oil as long as the oil remained in the body. As in the other experiments this dye is finally excreted through the sebaceous glands. Cocoanut oil injections never caused any local or general reaction in the animals used. This oil is the only oil experimented with which, on parenteral administration, seemed to have a definite though slight sparing effect on protein catabolism. Furthermore, the oil given subcutaneously to dogs had completely disappeared by the time the animals were autopsied. Peanut Oil Injections.—That the adult rats may be able to utilize some of the peanut oil administered parenterally is indicated by experiments in Series C, D, and E. It seems to make little difference in the utilization of this oil whether the animals are starved or not after its injection. Sudan III behaves, when administered with this oil, just as it does when given in solution in cocoanut oil. All evidence seems to indicate that the dog is probably unable to make any nutritive use of peanut oil administered parenterally.