When I dissect tissues for RNA isolation, I always put them directly into RNALater (fully submerged).  Sometimes we process within the hour, but we usually freeze the samples in the RNALater to be processed another day (-20C).  I've stored pituitaries and fat samples this way for months before processing them.  I'm sorry that you aren't having any luck!

We place the sample in 2 ml tubes and add 1.5 ml of RNALater and store at -80 ° C, and when we do the extraction washed 3 times with sterile double distilled water, that has worked very well, you should check your protocol, not think it's for the use of RNALater you do not have good quality RNA, the problem must be in another stage of the extraction. Best Regards!

Hi

You don't need to wash your samples from RNA later. What extraction kit/method are you using? You could also buy RNAse inhibitors from Applied Biosystems or Qiagen. 

Wishes,

Bassem

Thank's for your answers. We extract RNA with one-step isolation protocol and use TRI Reagent (Sigma). After precipitation with isopropanol RNA floats, so we need to centrifuge twice. That's why I was asking about washing samples before RNA extraction.