Comparing and Optimizing RNA Extraction from the Pancreas of Diabetic and Healthy Rats for Gene Expression Analyses.

Advanced differential gene expression analysis requires high-quality RNA. However, isolating intact pancreatic RNA is challenging due to abundant pancreatic ribonucleases, which limits efficient downstream gene expression analysis. RNA later treatment reduces endogenous ribonucleases effects through either pre-organ excision via organ mass or bile duct direct injection or organ mass injection post-isolation. We compared RNA extraction protocols to establish a reproducible and effective pancreatic RNA extraction method to obtain high RNA integrity number (RIN) values from healthy and streptozotocin (STZ)-induced diabetic rats for gene expression analyses. Different methods were tested focusing on RNase activity inhibition using RNA later (Qiagen) pre-harvest of the pancreatic tissue, and extracted RNA quality and concentration were analyzed using NanoDrop spectrophotometer, Agilent Bioanalyzer, and RT-PCR. Inclusion of several pre- and post-excision modifications in the RNeasy Mini Kit (Qiagen) protocol resulted in RIN values more than two-fold higher compared to those using the standard protocol. Additionally, RT-PCR amplification of the housekeeping gene, β-actin , revealed no differences in extracted RNA quality from healthy and STZ-induced diabetic rats. We compared and developed a more effective and reproducible pancreatic RNA extraction method from healthy and diabetic rats, which resulted in RNA of superior quality and integrity and is suitable for complex molecular investigations.