Influence of Iodine Deficiency on Free Choice between Alcohol and Water in Rats

Abstract

The effect of an iodine-deficient diet on the free choice between 10% alcohol and water was studied in male Wistar albino rats given first a 10% alcohol solution as sole drinking fluid for 10 days and then a free choice for 20 days during which an ordinary laboratory diet was available ad libitum. The alcohol consumption of each rat during this period was used as a base from which the change during the following test period of 20 days was calculated. Twenty-three rats were given thereafter an iodine-deficient diet ad libitum and 13 controls, the same diet with 30 mg of iodide per kg of diet added. At the end of this period all controls and the 13 of the iodine-deficient rats which weighed the least were anesthetized and blood samples were drawn for serum protein-bound iodine and cholesterol analyses. The thyroid glands of the animals were excised and weighed. The 10 remaining rats were maintained for the following 14 days with the iodine-deficient diet to which 30 mg of iodide per kg of diet had been added and their alcohol and water consumption during this time was observed. After the change from the ordinary to the iodine-deficient diet, a decrease in alcohol consumption and an increase in water consumption were observed. There were no marked differences between groups in total fluid consumption, food consumption or increase in body weight. During the iodine-deficient period the rats which had a low initial consumption of alcohol drank more alcohol than initially. There was no marked change in the intake by the rats with a high initial consumption. Addition of iodine to the diet of the iodinedeficient rats produced a prompt decrease in alcohol consumption to levels in the initial 20-day period. The level of serum protein-bound iodine was slightly but significantly lower in the iodine-deficient group (3.44 µg per 100 ml of serum) than in the group which had received an iodine-rich diet ( 4.59 µg per 100 ml). The cholesterol values of the two groups were not significantly different. The thyroid glands of the iodine-deficient group were slightly but not significantly enlarged.