SEX-DIFFERENCES IN AGE DEVELOPMENT OF A MOUSE INBRED STRAIN - BODY-COMPOSITION, ADIPOCYTE SIZE AND ORGAN WEIGHTS OF LIVER, HEART AND MUSCLES

The mouse inbred strain HLG has only recently been submitted for inter national registration. It has been widely used in radiological studies . Since these mice tend to become obese, they may be of interest for s tudies concerning fat metabolism. Therefore, the present ageing study examines the sex-specific development of body weight, body composition , adipocyte size as well as the organ weight of liver, heart and thigh muscles of the inbred strain HLG (54 males/53 virgin females) between day 40 and 360 of life. The body weight development showed a distinct sexual dimorphism, quickly increasing in the case of males but compar atively protracted in females until maturity. Significantly higher val ues for body and fat-free dry weight as well as body water were found in males of all ages. Body fat and adipocyte diameter were only higher in the 80 and 120 day-old males. Thus, the increase in female body we ight resulted largely through a rise in body fat as additionally evide nced by the sex-specific correlation of characteristics. A 2-fold anal ysis of variance showed sex differences in the relative weights of liv er and muscle, but not of the heart. A sex-specific close correlation was observed between body and liver weights in males until day 180. Co rrelations between body fat and other characteristics were only rarely found. Differences in coefficients of variation largely depended on t he characteristics. A higher variability was also found for some chara cteristics in the youngest groups (40 days). A sex-specific difference was only seen in the case of body fat content for 60 day-old mice (fe male>male).