To date, the supposed hypothesis of AR downregulation caused by AAS use is a mere anecdote that cannot be translated into the real-world scenario of muscle hypertrophy because, to the best of our knowledge, only a former study published nearly three decades ago suggests T-induced downregulation of ARs using rat cavernosum smooth muscle, in which finasteride was used to increase T levels instead of T administration [
37].
Nevertheless, taking into account the relationship between ARs and skeletal muscle receptors, it is unsubstantiated to claim that there is downregulation of ARs in response to AAS administration. There is an undeniable lack of evidence to support AAS use downregulating ARs, even when considering animal studies. Amid the paucity of direct evidence, a single, older study using cells from the corpus cavernosum of rats reported that T led to downregulation of ARs [
37]; however, instead of administrating T, finasteride was used as a means of increasing T concentration because of its actions in inhibiting 5-alpha reductase—then converting T to dihydrotestosterone [
37]. In contrast to this study, another in vitro experiment showed that T administration upregulates AR in cultured the skeletal muscle satellite cells and myotubes of a porcine [
38]. Thus, the latter study [
38] portrays the biological nexus between AASs and AR regulation with more specificity in an attempt to understand the mechanisms inherent in the muscle-building plateau than the former one [
37]. Furthermore, a couple of human studies show that T and oxandrolone upregulate myocyte AR [
39,
40]
Many animal and human studies support that T administration leads to satellite cell proliferation and increases the number of myonuclei [
58,
59,
60]. More importantly, supraphysiological doses of T increase the number of satellite cells and myonuclei in healthy men [
60]. After 20 wk of 125, 300, or 600 mg weekly doses of T enanthate, Sinha-Hikim et al., detected significant increases in myonuclear number for those subjects who received 300 (2.5 ± 0.8 to 5.0 ± 0.8%, n = 8) and 600 mg (2.5 ± 0.5 to 15.0 ± 1.5%, n = 5) [
60]. Equally important, the increase in satellite cell number correlated with changes in total (r = 0.548) and free T concentrations (r = 0.468) [
60].
Given the well-established effects of AASs on orchestrating satellite cells, one can contemplate crosstalk between ARs and signaling pathways involved in activating satellite cells from quiescence to proliferation, as the binding of AASs to ARs is imperative to afford satellite cell-mediated hypertrophy [
61].
Hence, based on the available literature, the hypothesis that the use of T and other AASs promote AR downregulation in skeletal muscle is an unwarranted assumption, as their effects on muscle mass accretion are evident.