I recently made some experiments about effects of pesticide on miRNA expression. Many databases I went through give large numbers of target mRNA based on predictation. As miRNA function may be context-dependent, I'm confused. How to know the validated exact target of miRNA via internet or database?

If you can give a little more details I might have some suggestions.
Specifically which organism are you studying and what target prediction site are you using?

Most target predictions algorithms are concentrated on finding seed matches between the miRNA and the 3' UTR of the mRNA. Some sites attempt to overlay functional data (reporter construct assays etc.). A lot of the time I find I need to combine data from different resources to be able to answer my specific questions.

If you do not want to post more details here feel free to PM me.