Evaluation of the cardiac autonomic nervous system in spontaneously non-insulin-dependent diabetic rats by 123I-metaiodobenzylguanidine imaging.
OBJECTIVE
To evaluate the sensitivity of 123I-labeled metaiodobenzylguanidine (123I-MIBG) scintigraphy in detecting diabetic autonomic nervous system disorders.


METHODS
Thirty-one-week-old male Otsuka Long-Evans Tokushima Fatty (OLETF) rats, an animal model of spontaneous non-insulin-dependent diabetes mellitus, were maintained for 8 weeks with or without 30% sucrose solution as a drinking water (n = 3 each). Long-Evans Tokushima Otsuka (LETO) rats (n = 3), served as controls. Plasma glucose and insulin levels were measured, and 123I-MIBG scintigraphy was performed with a gamma camera equipped with a pinhole collimator for animals. Plasma and cardiac tissue cathecolamine levels were also determined.


RESULTS
Plasma glucose levels of OLETF rats with and without sucrose loading (554+/-106 and 141+/-1.5 mg/dl respectively) were significantly higher than those of LETO rats (116+/-3.7 mg/dl). Norepinephrine concentrations in heart and plasma tended to be lower in diabetic rats. The washout rate of 123I-MIBG in diabetic rats was significantly higher than the rate in control rats. Cardiac uptake of 123I-MIBG, calculated as % dose/g of tissue, was significantly lower in diabetic rats than in control rats.


CONCLUSIONS
These results suggest that myocardial 123I-MIBG scintigraphy is suitable for assessing cardiac sympathetic activity noninvasively in diabetic states, even in the early stages.
Togane
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First Department of Internal Medicine, Toho University School of Medicine, Japan. skatayama@Saitama.med.ac.jp
D019797:3-Iodobenzylguanidine; D000818:Animals; D001786:Blood Glucose / Q000032:analysis; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000150:complications* / Q000000981:diagnostic imaging; D003929:Diabetic Neuropathies / Q000097:blood / Q000000981:diagnostic imaging*; D004837:Epinephrine / Q000097:blood; D006321:Heart / Q000000981:diagnostic imaging*; D007328:Insulin / Q000097:blood; D007457:Iodine Radioisotopes; D008297:Male; D009638:Norepinephrine / Q000097:blood; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals; D051381:Rats; D020334:Rats, Inbred OLETF
D001786:Blood Glucose; D007328:Insulin; D007457:Iodine Radioisotopes; D019275:Radiopharmaceuticals; D019797:3-Iodobenzylguanidine; D009638:Norepinephrine; D004837:Epinephrine