Increased lipid oxidation heralds diabetes onset in DR.lyp/lyp rats.
OBJECTIVE
The BB rat model of type 1 diabetes exhibits altered body weight gain and body temperature regulation prior to hyperglycemia onset, implying the existence of as yet unidentified biomarkers of autoimmune processes that destroy pancreatic beta cells. To investigate this hypothesis, we compared the metabolic profile of diabetes-resistant DR.lyp/+ rats and their diabetes-prone, congenic DR.lyp/lyp littermates in the days leading up to diabetes onset.


METHODS
Except for the Gimap5 mutation on chromosome 4, congenic DR.lyp/lyp rats are genetically identical to DR.lyp/+ littermates. They invariably develop hyperglycemia at 46-81 days of age, whereas DR.lyp/+ rats do not develop diabetes. In addition to daily food intake and body weight, indirect calorimetry was performed continuously on male DR.lyp/lyp and DR.lyp/+ rats (n=6/group) for 6-18 days to measure locomotor activity, VO (2), VCO (2) and RQ.


RESULTS
DR.lyp/lyp rats exhibited a progressive decrease of RQ compared to DR.lyp/+ rats 0.005+/-0.001 units/day (p<0.005). Limiting the analysis to the six days prior to diabetes onset revealed a larger decrease of 0.007+/-0.002 units/day (p<0.001) in DR.lyp/lyp animals, whereas RQ of the DR.lyp/+ rats remained unchanged. This metabolic change occurred prior to hyperglycemia onset and was not associated with changes of any other parameter.


CONCLUSIONS
Diabetes onset in DR.lyp/lyp rats is heralded by a progressive shift towards lipid oxidation relative to carbohydrate metabolism.
Akesson
L
L
Department of Clinical Sciences, Clinical Research Center, Lund University, Malmö, Sweden. Lina.akesson@med.lu.se
Gelling
R W
RW
Jensen
R
R
Ogimoto
K
K
Fuller
J M
JM
Pefley
R
R
Manavi
S
S
Lernmark
A
A
Schwartz
M W
MW
D000818:Animals; D002151:Calorimetry; D003922:Diabetes Mellitus, Type 1 / Q000378:metabolism*; D004327:Drinking Behavior; D005247:Feeding Behavior; D005838:Genotype; D006799:Housing, Animal; D007515:Islets of Langerhans / Q000503:physiopathology; D015227:Lipid Peroxidation; D008297:Male; D009043:Motor Activity; D051381:Rats; D011913:Rats, Inbred BB; D011919:Rats, Inbred Strains; D014867:Water
D014867:Water