Phenotyping of congenic dipeptidyl peptidase 4 (DP4) deficient Dark Agouti (DA) rats suggests involvement of DP4 in neuro-, endocrine, and immune functions.
BACKGROUND
Treatment of diabetes type 2 using chronic pharmacological inhibition of dipeptidyl peptidase 4 (DP4) still requires an in-depth analysis of models for chronic DP4 deficiency, because adverse reactions induced by some DP4 inhibitors have been described.


METHODS
In the present study, a novel congenic rat model of DP4 deficiency on a "DP4-high" DA rat genetic background was generated (DA.F344-Dpp4(m)/ SvH rats) and comprehensively phenotyped.


RESULTS
Similar to chronic pharmacological inhibition of DP4, DP4 deficient rats exhibited a phenotype involving reduced diet-induced body weight gain and improved glucose tolerance associated with increased levels of glucagon-like peptide-1 (GLP-1) and bound leptin as well as decreased aminotransferases and triglycerides. Additionally, DA.F344-Dpp4(m)/SvH rats showed anxiolytic-like and reduced stress-like responses, a phenomenon presently not targeted by DP4 inhibitors. However, several immune alterations, such as differential leukocyte subset composition at baseline, blunted natural killer cell and T-cell functions, and altered cytokine levels were observed.


CONCLUSIONS
While this animal model confirms a critical role of DP4 in GLP-1-dependent glucose regulation, genetically induced chronic DP4 deficiency apparently also affects stress-regulatory and immuneregulatory systems, indicating that the use of chronic DP4 inhibitors might have the potential to interfere with central nervous system and immune functions in vivo.
Frerker
Nadine
N
Functional and Applied Anatomy, Hannover Medical School, Hannover, Germany.
Raber
Kerstin
K
Bode
Felix
F
Skripuletz
Thomas
T
Nave
Heike
H
Klemann
Christian
C
Pabst
Reinhard
R
Stephan
Michael
M
Schade
Jutta
J
Brabant
Georg
G
Wedekind
Dirk
D
Jacobs
Roland
R
Jörns
Anne
A
Forssmann
Ulf
U
Straub
Rainer H
RH
Johannes
Sigrid
S
Hoffmann
Torsten
T
Wagner
Leona
L
Demuth
Hans-Ulrich
HU
von Hörsten
Stephan
S