C-peptide prevents and improves chronic Type I diabetic polyneuropathy in the BB/Wor rat.
OBJECTIVE
Insulin and C-peptide exert neuroprotective effects and are deficient in Type I (insulin-dependent) diabetes mellitus but not in Type II (non-insulin-dependent) diabetes mellitus. These studies were designed to test the preventive and interventional effects of C-peptide replacement on diabetic polyneuropathy in the Type I diabetic BB/Wor rat.


METHODS
Diabetic BB/Wor rats were replaced with rat C-peptide from onset of diabetes and between 5 and 8 months of diabetes. They were examined at 2 and 8 months and compared to non-C-peptide replaced BB/Wor rats, Type II diabetic (non-C-peptide deficient) BB/Z rats and non-diabetic control rats. Animals were monitored as to hyperglycaemia and nerve conduction velocity (NCV). Acute changes such as neural Na+/K+-ATPase and paranodal swelling were examined at 2 months, morphometric and teased fiber analyses were done at 8 months.


RESULTS
C-peptide replacement for 2 months in Type I diabetic rats prevented the acute NCV defect by 59% (p < 0.005), the neural Na+/K+-ATPase defect by 55% (p < 0.001) and acute paranodal swelling by 61% (p < 0.001). Eight months of C-peptide replacement prevented the chronic nerve conduction defect by 71% (p < 0.001) and totally prevented axoglial dysjunction (p < 0.001) and paranodal demyelination (p < 0.001). C-peptide treatment from 5 to 8 months showed a 13% (p < 0.05) improvement in NCV, a 33% (p < 0.05) improvement in axoglial dysjunction, normalization (p < 0.001) of paranodal demyelination, repair of axonal degeneration (p < 0.01), and a fourfold (p < 0.001) increase in nerve fibre regeneration.


CONCLUSIONS
C-peptide replacement of Type I BB/Wor-rats partially prevents acute and chronic metabolic, functional and structural changes that separate Type I diabetic polyneuropathy from its Type II counterpart suggesting that C-peptide deficiency plays a pathogenetic role in Type I diabetic polyneuropathy.
Sima
A A
AA
Department of Pathology, Wayne State University, Detroit, Michigan 48201, USA. asima@med.wayne.edu
Zhang
W
W
Sugimoto
K
K
Henry
D
D
Li
Z
Z
Wahren
J
J
Grunberger
G
G
D000818:Animals; D001369:Axons / Q000187:drug effects; D002096:C-Peptide / Q000627:therapeutic use*; D003922:Diabetes Mellitus, Type 1 / Q000503:physiopathology*; D003929:Diabetic Neuropathies / Q000188:drug therapy* / Q000503:physiopathology; D004195:Disease Models, Animal; D008297:Male; D009186:Myelin Sheath / Q000187:drug effects; D009416:Nerve Regeneration / Q000187:drug effects; D009431:Neural Conduction / Q000187:drug effects / Q000502:physiology; D051381:Rats; D011913:Rats, Inbred BB; D013997:Time Factors
D002096:C-Peptide