Vol. 276, Issue 4, E762-E765, April 1999
The obese gene is expressed in lean littermates of the
genetically obese mouse (C57BL/6J
ob/ob)
Edwin W.
Haller1,
Lorentz E.
Wittmers Jr.1,
Irina V.
Haller1, and
Ronald R.
Regal2
Departments of 1 Medical and
Molecular Physiology and of
2 Mathematics and Applied
Statistics, University of Minnesota, Duluth, Minnesota 55812
Some individuals of
the mixed group of "lean" littermates
(+/ob and +/+) of (C57BL/6J
ob/ob) often suggest phenotypic
characteristics of ob/ob animals.
Therefore, it was of interest to determine whether expression of the
ob gene had physiological significance
in +/ob animals. Body weight (BW),
fasting blood glucose (FBG), and body core temperature
(Tr) were monitored between 62 and 364 days of age in +/+ and +/ob
mice. Among females but not males,
+/ob mice were heavier
(P = 0.003) and FBG levels were
greater (P = 0.04) than in +/+
animals. Comparison of Tr
indicated differences suggesting falling
Tr in
+/ob but rising
Tr in +/+ mice with age in males but not females. Multivariate analysis of variance yielded genotype effects for both males (P = 0.002) and
females (P = 0.02). BW, FBG, and
Tr alone were sufficient at the
75% level for genotypic characterization and separation of +/? animals
as +/ob or +/+; clearly, expression of the
ob gene in heterozygotes of the
+/ob animal may make the mixed +/?
group inappropriate as lean controls.
genetic obesity; ob gene product; phenotypic differentiation; ob/ob
experimental controls
