Hey guys, long-time lurker, first time poster. I’ve never used Propecia, but was on TRT for 4 years, and gradually became tolerant to the effects of Testosterone, eventually ending up with complete loss of libido. This was despite all labwork returning normal (TT, Free T, E2, androgens, etc). I realize my situation may appear different from those on this board, but I am starting to believe that though the origin of my libido loss may be different, the underlying issue is the same–a mismatch of Dopamine levels and Dopamine receptors in the brain.
This is pure speculation of course, but reading this thread, a few personal observations seem to support the dopamine receptor downregulation hypothesis. I have been tolerant to the effects of supplemental Testosterone for a few years now. Not only libido, but even secondary sexual characteristics like muscle wasting, dry skin, etc. 2 years ago, I was taking 100mg/wk Testosterone injections as part of my TRT, and developed a temporary but strong coffee habit, consuming upwards of 15-20 cups a day for a month. I had a full caffeine tolerance at this point as well–I could drink as much coffee as I wanted and fall asleep right after.
When I returned home, I went cold turkey. That resulted in 4 days of the worst migraines of my life, as my dopamine levels crashed (speculation). I also stopped Testosterone replacement at this time in order to do a reset of my HPA, as per my physician. I resumed Testosterone replacement with Androderm instead of injectable, to see if another form of delivery would affect libido. Well my libido skyrocketed higher than it had been in years. This lasted a month before dropping off.
Now this could easily be theorized that the libido increase resulted from the transdermal Testosterone delivery, which increases DHT much more than injectable form. But I had been on doses of injectable Testosterone as high as 300mg/wk, which should have resulted in higher DHT, yet never increased my libido at all. I had a full tolerance to supplemental Testosterone. It was only when I went through severe caffeine withdrawals that I had a sudden surge in libido.
I speculate that the caffeine withdrawal increased Dopamine receptor levels, which re-sensitized my brain to Testosterone, restoring libido temporarily. After a month, the surge in Dopamine levels from Testosterone may have once again downregulated the amount of Dopamine receptors, bringing me back to the old state of loss of libido. Again, this is pure speculation, as I didn’t do the proper blood testing to back up my anecdote with data, but it does offer a better explanation than has ever been offered to me by any Endocrinologist or physician.
Former, have you, or do you plan on experimenting with Xyrem or any other dopamine antagonist? I thought of Seroquel as well, since it is a Dopamine antogonist but which has a few benefits, including possibly not raising Prolactin levels too much. From Wikipedia:
Seroquel also has a short half-life of only 6 hours, making it perfect to take before bed (it is commonly used as a sleeping pill). I’m hypothesizing that if someone were to take a Dopamine antagonist during sleep repeatedly, it may increase Dopamine receptor levels and resensitize the brain to Dopamine, allowing Testosterone to have the proper effect on libido. I’m not suggesting anyone be the guinea pig on this idea, but maybe there have been studies done on this effect that we could look to for further confirmation.