Of course you can. Actually,reading glasses often come in prescription lenses. But the strength of its prescription is usually weaker than the regular one.So ask your doctor what strength you need for reading glasses .
Maybe you can't. You mean your reading glasses are bought from over the counter. If so, you can't put prescription lenses in your reading glasses because reading glasses over the counter are ready-made. The lenses of these reading glasses cannot be replaced with new lenses. I think you should get a new pair of prescription reading glasses.