We use recommended dose to treat our STZ-induced hyperglycemic rodents, but most have gone hypoglycemic and some die?
Unlike natural diabetes, STZ induction gives varying severity in hyperglycemia. The recommended dose is for severly diabetic (defined as off the meter scale, >400 mg/dL or > 20 mmol/L) animals. Hyperglycemia less than as just defined, requires less than the recommended doses. To get reproducibly severe diabetes in mouse, the STZ must be prepared just before injection at pH 4 (up to 4 injections at 65 mg/kg may be required). For rats, practise tail vein sampling of 0.2 mL of blood using a 30G needle with success rate of 7 out of 10 trials. Then use 50 mg/kg freshly prepared STZ at pH 4 (not 65 mg) IV into the tail vein. All rats will become severly diabetic in 3 days. Implant after 7 days.
