[Neuroscience] what differences we can expect using rat or mice in LTP recording and how animal age involved?

[blueocean12 from tom.com]

Hey,
I do electriphysiological recording of hippocampus slice (recording
LTP amplitude)of mice but the result I got is  different with other
published results. The differces I found between my experiment and
theirs is that they use young rats but I use mice. Anybody can tell me
if it is reasonable that  the different result from we use different
animal. Will we expect different results using rat? And what is the
likely lifespan of rat and mice? What is the define we set for
young(adolescent) or adult rats?
Thanks a lot!