I recently had the same frequent reboot problem on a newer macbook pro running the latest El Capitan. The screen would just go black then a white apple logo would appear. Log back into the system and a kernel panic message would be presented.
It turns out that the Spotlight index database had been corrupted. Not certain as to how the database got corrupted, perhaps software installs with large file and directory numbers.
The corruption was corrected by using System Preferences > Spotlight > Privacy to remove the existing spotlight database. When you get into the Spotlight Privacy window no existing directory or drive will be present.
Create one by adding the Macintosh HD by selecting the "+" and then reboot the system.
Once the system is up, open System Preferences > Spotlight > Privacy again and remove the added Macintosh HD.
Reboot the system once again
This should solve the corrupted Spotlight database and the reboot/kernel panic should not occur.
Best Answer
I would suggest visiting a Apple Authorized Service Provider to troubleshoot this (what i suspect is a hardware issue) https://www.apple.com/support/macbookpro-videoissues/
Unfortunately MacBook Pro (15-inch, Mid 2010) intermittent black screen or loss of video Quality Program has ended https://support.apple.com/en-us/HT203554