Decreased VIP content in peripheral nerve from streptozocin-induced diabetic rats.
After induction of diabetes with streptozocin (STZ-D) in rats, we measured vasoactive intestinal polypeptide (VIP) content in sciatic nerve and spinal cord obtained from nondiabetic, untreated STZ-D, and insulin-treated STZ-D rats. Eight weeks after the onset of diabetes, caudal nerve conduction velocity (NCV) in the untreated STZ-D rats (n = 13) was slower than in the controls (n = 11; mean +/- SE 30.9 +/- 0.6 vs. 41.4 +/- 1.8 m/s, P less than 0.001). The decrease in NCV was less marked in the insulin-treated STZ-D rats (n = 11; 36.3 +/- 0.9 m/s, P less than 0.05 vs. control). VIP content in sciatic nerve decreased in the untreated STZ-D rats (1.33 +/- 0.23 ng/g wet wt) compared with the other groups (control, 3.10 +/- 0.44, P less than 0.01; insulin-treated STZ-D, 2.44 +/- 0.55, P less than 0.05). However, in spinal cord, VIP content was not significantly different among the three groups. The VIP levels in sciatic nerve showed a positive correlation with NCV (r = 0.430, P less than 0.01). In addition, an inverse correlation between VIP levels and blood glucose levels was observed (r = -0.5624, P less than 0.001). NCV was also inversely correlated with blood glucose levels (r = -0.7662, P less than 0.001). Together with a previous morphological study, these findings suggest a possible causal relationship between reduced VIP content and diabetic neuropathy.
Third Department of Internal Medicine, Faculty of Medicine, Kyushu University, Fukuoka, Japan.
K
K
Noda
F
F
Umeda
H
H
Ono
A
A
Hisatomi
Y
Y
Chijiiwa
H
H
Nawata
H
H
Ibayashi
D000818:Animals; D001786:Blood Glucose / Q000032:analysis; D001835:Body Weight; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism*; D003929:Diabetic Neuropathies / Q000378:metabolism*; D007328:Insulin / Q000627:therapeutic use; D008297:Male; D009431:Neural Conduction; D011863:Radioimmunoassay; D051381:Rats; D011919:Rats, Inbred Strains; D012584:Sciatic Nerve / Q000378:metabolism*; D013116:Spinal Cord / Q000378:metabolism*; D014660:Vasoactive Intestinal Peptide / Q000032:analysis*
D001786:Blood Glucose; D007328:Insulin; D014660:Vasoactive Intestinal Peptide