If I understand you correctly, you created a MIDI sequence within Protools and would like to trigger the synths in Reason to playback the parts and have the audio from Reason playback through your Protools session. Have I got it? You need to look into the Rewire capabilities of your versions of Protools and Reason. Rewire is a utility that does just what your asking, brings sounds from Reason, Rebirth etc. etc. and plays them back through your DAW. It also can be set up to send MIDI messages from your DAW to your Rewire capable software synths (Reason in this case). I don't really know Protools well enough to guide you through this but I bet if you post this question to the DAW forum, you'll find some people that are doing this all day long.

Regards,
Bob

aux return with Reason set at an insert
midi track out to a reason channel and chose the synth
drums are often on CH10

to record the reason plug to a track ... use a bus and route to a new Audio Track in record mode.