On the experimental production of lack of carbohydrates,and on the carbohydrate metabolism of the central nervous system.

Abstract

To gain further insight into the genesis of the hypoglycaemic symptoms and other problems of carbohydrate metabolism it appeared advisable to dispose of various methods of depriving the organism of its stores of carbohydrates. In various former publications from the Berne Physiological Institute, mention has been made of methods suitable for this purpose. We have now worked out such a method that one is able experimentally to deprive the organism almost completely of its store of carbohydrates. The method, as applied to rats, consists in the following procedure: The rats are fed for a few days with Witte's pepton, then with thyroid gland preparations, and finally phlorhizin is injected according to Coolen's methods, and the animals are then worked in a treadmill. The treatment with Witte's pepton and with thyroid gland preparations must be carefully regulated according to the condition of the animals; they are especially sensitive to feeding with Witte's pepton. With this method we succeeded in lowering the carbohydrates of the liver 96 per cent, the carbohydrates of the muscle 85 per cent, and the blood sugar to the same low value as in the hypoglycaemic state after insulin.

We were particularly interested in the carbohydrate content of the brain. We found per gram of brain an average amount of 1.23 mg. carbohydrate of which 0.75 mg. is glycogen. This socalled glycogen is the product of analysis according to the method of Pflüger.

As a result of our experimental proceedings the carbohydrates, especially the content of glycogen, had been diminished by something like 90 per cent, the glycogen content of the brain had not diminished more than about 20 per cent. Also after insulin, where we obtained in the case of the liver, the muscles and the blood, the same results as were attained by the method described above, the glycogen content of the brain was only slightly decreased. The amount of this diminution seemed to depend upon whether or not the animals showed symptoms of convulsions. Therefore we injected strychnine. Like insulin this drug only causes a type of convulsions which is not very marked. Although the decrease in glycogen content of the brain in these cases was more pronounced, the diminution of the carbohydrates of the tissues is at the same time very much less than in the former experiments.