Study was done on rat teste tissues, nontheless interesting to note their observation about Finasteride. This was put out by the US Environmental Protection Agency. They likely expected Finasteride to INCREASE, not DECREASE, Testosterone.
Sliced Testis Assay Prevalidation: Multichemical Study
epa.gov/scipoly/oscpendo/pub … _17_04.pdf
“This study was designed to evaluate the sliced testis assay for the ability to screen chemicals with known mechanisms of action for anti-steroidogenic activity and/or for cytotoxicity.”
Finasteride (5-alpha reductase inhibitor)—at 10, 100, and 1000 :M finasteride, the testosterone concentrations were decreased 50, 94, and 97%, respectively, which was significant at all 3 doses. Significant linear and cubic component of trend were noted.
Also, finasteride produced significantly increased LDH levels at 1000 :M, with no concentration-related increases at 10 or 100 µM (Tables 11 and 12). A significant linear trend component was observed.
…Finasteride, a 5a-reductase inhibitor, was a potent inhibitor of testosterone levels at all 3 concentrations, down to 97% reduction at 1000:M. Again, either there is a local feedback loop or a hemostatic equilibrium between testosterone and DHT (so that reductions in DHT cause reductions in testosterone), or finasteride affects steroidogenesis in the sequence to produce testosterone.
This latter possibility is very unlikely since finasteride has been well researched, its mechanism of action identified and it is used in pharmaceutical preparations to restore hair growth in men (and women) with male pattern baldness, under DHT control. The assay response was opposite of what was expected.