Is there any limit for the actuation of the dslr's especilly with Nikon D5000?

Cheers!

Not really.

The shutter is a mechanical piece which will eventually fail, but it is good for at least 100, 000 actuations. That's 30 actuations every day for ten years. And even then that's just the minimum to which it has been tested, it doesn't mean that it will fail then. Several times that many actuations are not unheard of.

So you'll probably long since have upgraded to the successor of the now brand new D7000 long before you come even close to shutter failure.

In short, yes there's a limit, but it's so very high that it has no practical relevance whatsoever.

Not as such. It won't get to 100, 000 and stop working.

Shutters are generally rated to a minimum standard. So say they are rated for 100, 000 actuations, that means that it is expected to survive a minimum of 100, 000 clicks before it stops firing at the correct speeds.