 However, due to trenbolone's potent progestogenic activity, gynecomastia, which is characterized by development and swelling of breast tissue, may still be possible.Stimulation of estrogenic mechanisms are enforced by progestogenic activity as trenbolone acetate and its compounds bind with high affinity to the progesterone receptor.It has been assumed that gynecomastia as a result of trenbolone use is due to a buildup of the hormone prolactin; however, a variety of studies conclude that it is the progestogenic activity of trenbolone promoting this and not prolactin.