My study requires the induction of STZ in 30 Sprague-Dawley rats (either sex) to develop type 2 diabetes. My protocol was:
1) Fast the rats overnight.
2) Prepared STZ solution in ice-cold citrate buffer (0.1 M, pH 4.5) and injected i.p. within 5 minutes of dissolving it. Dose used was 50 mg/kg.
3) Fed them with 10% fructose water for 24 hours post injection and gave food ad libitum.
4) Checked for blood glucose levels (BGL) 4 days after injection. Rats were fasted for 24 hours before checking the blood glucose levels.
When compared to the normal BGL, some of my rats had their BGLs around the normal fasting BGL range (4.0 - 6.5 mmol/L) while some were above 11 mmol/L.
Could there be any explanation to this? I had my supervisor's help to inject the rats as he has mastered the i.p injection technique and thus, error in the technique could be ruled out.
While you fasted the rats overnight, individual variations in the duration of fasting may impact baseline blood glucose levels. Some SD rats might have metabolized their glucose reserves differently during the fasting period.
It is also important to note that, rats may exhibit varying degrees of insulin resistance, impacting their ability to regulate blood glucose levels. This could contribute to the observed differences in post-STZ induction BGL.
Perhaps you can conduct additional analyses, such as measuring insulin levels and histopathological examinations of pancreatic tissue. All these in combination, could help explain your findings.
Kabelo Mokgalaboni thank you for your explanation. I suppose variation could be a factor. I'll take that into consideration.
Dear Balachandran,
I collaborated on a protocol to which the diabetic induction methodology was very similar (or the same, I don't exactly remember the values of STZ injected) and the variability between animals was very large (there were approximately 90 animals) as was the problem you had. I spoke to some researchers who used the same protocol and the same problem was common among all. Interestingly, one of the researchers responded that one of the problems he found in his protocol was the temperature of the room where the animals were located. The temperature was lower than suggested in the literature. However, most responses were similar, there seems to be no common explanation for the great variability between animals. However, some suggested applying an additional dose of STZ despite the methodological impact.
I hope you can solve the problem.
Good luck and kind regards.
One paper suggested that the damage caused by STZ is reversible so you may need to give an additional dose or try high dose of STZ. You also can detect BGL after 2 weeks of diabetes induction
- Badges
- Science topic