I have seen a couple of sources where folks say they have called Taurus and been told the pistols were not +P rated. I take that for what it it worth, which is not much.
I will say two things about +P ammo and use -- my opinion, nothing more. First, I see little real need for +P loadings. Yes, they give better performance by many measures, but at the cost of greater recoil and faster gun wear, regardless of what gun you are talking about. Still, life is a series of trade-offs, and trading a bit of those things for better performance, even if more theoretical than real, is not necessarily a bad choice.
Second, as to the PT145 or any other reasonably well-made modern semiauto, I would have no qualms whatsoever in doing a moderate amount of +P shooting if a +P load showed me outstanding accuracy. Probably the critical item in terms of the gun would be the recoil spring, and if you choose to shoot more than a few +Ps every once in a while, I would obtain spares and swap them out pretty regularly.
My personal .45 carry load is the Winchester 230 gr. JHP stuff you can get at WalMart because it shoots wonderfully well in my Glock 36. I am sure my gun would handle +P 185s with no sweat, but I choose to avoid the bother and expense when I already have a load capable of better accuracy than I can muster. In no way are a few FPS less going to cause that big ol' slug with a cavernous hollowpoint to be harmless...