Other Modulator Efforts PR, MR, AR, PPAR, FXR and LXR

The theory of selective nudear receptor modulation to achieve therapeutic value by an optimized activity profile different from the natural ligand has been also experimentally studied in several other receptors. 

An example from the PR is the steroid ligand asoprisnil, which has been shown to produce antiuterotrophic effects with only minimal labor-inducing and breakthrough bleeding effects [76]. 

Eplerenone, a selective MR modulator, was discovered decades ago and has recently received approval as a treatment for hypertension [77]. This synthetic steroid derivative has a higher specificity for MR relative to other nuclear receptors and works as a partial antagonist of aldosterone [78]. 

Modulators of the AR for application in prostate cancer and possibly treating the neurological and muscular degenerative symptoms of androgen defidency form the basis of another field of intense research efforts [79,80]. LGD2226 is a recent example of a tissue-selective AR modulator, which seems to retain some anabolic effects on bone and muscle with reduced proliferative effects on the prostate [81]. 

More experimental studies will be necessary to better understand the molecular basis of modulator effects both for the steroid receptor and nonsteroid receptor modulators. 

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