Male Sprague-Dawley rats weighing between 240 and 280 g
were randomly assigned to diabetic or control groups, and
diabetes was induced by a single intraperitoneal injection of
streptozotocin (65 mg/kg body weight) in 0.1 M citrate buffer
pH 4.6 (Sigma Poole, Dorset, UK). The diabetic state was
characterized by cessation of growth, polyuria/polydipsia > 200
mL/d and persistent blood glucose levels > 15 mM/L. After 2-
and 4-month durations of diabetes, diabetic animals and control
rats were killed by an overdose of sodium pentobarbital.