Hereditary Obesity of Yellow Mice

Abstract

In the course of studies on the hereditary obesity of yellow mice first described by Dan-forth, 1 , 2 the following observation was made.

A group of S obese females was permitted unlimited amounts of water and Purina dog chow pellets throughout the experiment. Their food intake was measured at 2-6-day intervals, and the caloric intake per mouse per day calculated from a value (3.50 cal./g) obtained by chemical analysis. At varying intervals they were also allowed to drink for a few days one of the following at a time: 10% and 20% solutions of dextrose, 50% sucrose, olive oil, and human plasma with a protein concentration of 17.3%. The unrestricted daily caloric intake per mouse of each of these (excepting olive oil) was calculated. Simultaneously, identical steps were taken with a group of 3 normal albino female mice.

Fig. 1 shows the results. Briefly, none of these substances caused a gain in body weight of the normal mice; within the limits of error their caloric intake remained practically constant (see below). But the obese mice gained weight in three 4-day periods: 2.2 g with 20% dextrose, 3.0 g with 50% sucrose, and 4.4 g with olive oil. The caloric intake during 2 of those periods increased by about 12 calories and 24 calories (20% and 50% sugar, respectively), enough to explain most or all of the increased body weight as fat deposition. Moreover, when the sugar or oil was withheld, body weight fell to the original level during a few days in which there was an appropriately reduced caloric intake; surprisingly, under the same conditions, there was also a transient reduction of caloric intake cf the normal mice without loss of weight.