Animal experiment:

Rats: Prostate and seminal vesicles are studied in 3-4-month-old 250-300-g rats after orchidectomy (ORX). Nine days after surgery, animals are injected (subcutaneously) daily with test compounds for 17 days, and the weight of the seminal vesicles (SVs) is compared with ORX rats treated with vehicle or DHT as a positive control.

MK-0773 is a selective androgen receptor modulators (SARMs) that binds to AR with an IC50 of 6.6 nM. IC50: 6.6 nM (AR)

The IC50 of MK-0773 binding to AR is increased 3.5-fold in the presence of 25% rat serum and 13-fold in the presence of 25% human serum, indicating that it binds to serum proteins. The affinity of MK-0773 for AR across species is evaluated using COS cells transfected with AR, and IC50 values are very similar in four species (rat, 0.50 nM; dog, 0.55 nM; rhesus, 0.45 nM; human, 0.65 nM)[1].

MK-0773 (6 and 80 mg/kg, s.c.) produces exposure-related stimulatory effects on cortical BFR and LBM in the OVX rat model. MK-0773 (5, 15, and 80 mg/kg, s.c.) increases seminal vesicle weights, and has reduced effects on the prostate. The partial agonism and tissue selectivity of MK-0773 does not translate into differential effects on lipid metabolism in OVX rats[1].

[1]. Schmidt A, et al. Discovery of the selective androgen receptor modulator MK-0773 using a rational development strategy based on differential transcriptional requirements for androgenic anabolism versus reproductive physiology. J Biol Chem. 2010 May 28;285