C-peptide prevents hippocampal apoptosis in type 1 diabetes.
To explore mechanisms underlying central nervous system (CNS) complications in diabetes, we examined hippocampal neuronal apoptosis and loss, and the effect of C-peptide replacement in type 1 diabetic BB/W rats. Apoptosis was demonstrated after 8 months of diabetes, by DNA fragmentation, increased number of apoptotic cells, and an elevated ratio of Bax/Bcl-xL, accompanied by reduced neuronal density in the hippocampus. No apoptotic activity was detected and neuronal density was unchanged in 2-month diabetic hippocampus, whereas insulin-like growth factor (IGF) activities were impaired. In type 1 diabetic BB/W rats replaced with C-peptide, no TdT-mediated dUTP nick-end labeling (TUNEL)-positive cells were shown and DNA laddering was not evident in hippocampus at either 2 or 8 months. C-peptide administration prevented the preceding perturbation of IGF expression and reduced the elevated ratio of Bax/Bcl-xL. Our data suggest that type 1 diabetes causes a duration-dependent programmed cell death of the hippocampus, which is partially prevented by C-peptide.
Li
Zhen-guo
ZG
Department of Pathology, Morris J. Hood Jr. Comprehensive Diabetes Center, Wayne State University School of Medicine, Detroit, Michigan 48201, USA.
Zhang
Weixian
W
Sima
Anders A F
AA
D000818:Animals; D002096:C-Peptide / Q000494:pharmacology*; D053938:DNA Fragmentation; D003922:Diabetes Mellitus, Type 1 / Q000473:pathology*; D006624:Hippocampus / Q000187:drug effects / Q000473:pathology*; D008297:Male; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D051381:Rats; D011913:Rats, Inbred BB; D051028:bcl-2-Associated X Protein; D051020:bcl-X Protein
C494828:Bax protein, rat; C494813:Bcl2l1 protein, rat; D002096:C-Peptide; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D051028:bcl-2-Associated X Protein; D051020:bcl-X Protein