Proviron is a non-anabolic androgen, so therefore theoretically, it should not do anythign to your HPTA. Also, proviron is commonly used at the end of a cycle with clomid because it's an estrogen antagonist.
"Proviron strongly suppresses the forming of estrogens no re-bound effect occurs after discontinuation of use of the compound as is the case with, for example, Nolvadex where an aromatization of the steroids is not prevented. One can say that Nolvadex cures the problem of aromatization at its root while Nolvadex simply cures the symptoms.....With Proviron the athlete obtains more muscle hard-ness since the androgen level is increased and the estrogen concen-tration remains low. This, in particular, is noted positively during the preparation for a competition when used in combination with a diet. " (I didn't write this, that's why I quoted it.)
This should answer your questions.
...bd