Pregnenolone | More Than Just An Excellent Endocrine Precursor

Pregnenolone | More Than Just An Excellent Endocrine Precursor

A Most Important Compound

Pregnenolone is perhaps one of, if not, the most important steroid hormone in our body. It was discovered by the brilliant German biochemist Adolf Butenandt and his colleagues, in 1934. Adolf Butenandt’s work on pregnenolone and other related steroid hormones eventually earned him a Nobel prize. These were incredibly important discoveries at the time, and drastically improved our understanding of hormone function throughout the human body. Pregnenolone was perhaps one of the most important discoveries, when we consider its relationship to all the other steroid hormones.

Pregnenolone | More Than Just An Excellent Endocrine Precursor

As can be seen in figure 1 pregnenolone exists at the very beginning of the process of steroidogenesis, which is the process by which all steroid hormones are synthesized. This means that without pregnenolone, we can’t have testosterone, estrogen or even cortisol!

In our bodies, pregnenolone is synthesized from cholesterol, by the cholesterol side-chain cleavage enzyme, which is also referred to as CYP11A1. This enzyme is part of the cytochrome P450 enzyme superfamily, which may sound familiar to many of you, because it is the main class of enzymes which metabolizes the majority of the compounds we supplement. For example, caffeine is metabolized by CYP3A4, which is also in the cytochrome P450 superfamily! The cholesterol side-chain cleavage enzyme is oftentimes thought to be the rate limiting step in steroid hormone synthesis, because if cholesterol isn’t being converted to pregnenolone, it shuts down all steroid hormone synthesis. However,  it appears to be a little bit trickier than this because cholesterol can’t just be converted to pregnenolone anywhere in the body. This is due to the fact that the cholesterol side-chain cleavage enzyme only exists in the inner membrane of our mitochondria.

Getting cholesterol from the outer mitochondrial membrane, to the inner mitochondrial membrane, where it can be converted into pregnenolone, is no small feat! This is facilitated by a transport protein called steroidogenic acute regulatory protein (StAR). With this in mind, perhaps StAR has an even bigger effect on the rate of steroidogenesis, because without it, cholesterol won’t be in the right location for conversion to pregnenolone. With pregnenolone supplementation however, we can bypass both the cholesterol side-chain cleavage enzyme, and StAR. Of course, this then does depend on pregnenolone being able to make it into the mitochondria of cells in order to act as a driver of steroidogenesis.

When it comes to cellular uptake of steroid hormones, passive diffusion appears to be one of the predominant mechanisms. This mechanism depends on the steroid hormones being sufficiently lipophilic. Luckily, pregnenolone is incredibly lipophilic. Perhaps more so than any of the other steroid hormones. Logically, this makes sense too. Pregnenolone is the master steroid hormone precursor, so it seems fairly pertinent that it would have the ability to easily pass into and out of cells. This means that with pregnenolone supplementation, we can easily bypass the rate limiting step of steroidogenesis, which makes supplemented pregnenolone a fantastic stimulator of steroidogenesis!

Pregnenolone | More Than Just An Excellent Endocrine Precursor

Dosed & Confused

A lot of confusion exists about the proper dosage level for pregnenolone, with most thinking that more of a good thing, should result in more positive results. However, it’s not always that easy! This of course harkens back to the famous debate of melatonin dosing, with most supplement companies opting for very high doses of melatonin, while the research indicates that very low doses of melatonin, in the microgram range, are actually the most optimal dosage level. To the uninformed, such low doses of melatonin were a tough sell in a sea of high dose melatonin products, and there was a lot of confusion around this subject. However, over the years, it has become clear that the effects of low dose melatonin, in general, are superior. We face a similar level of confusion when it comes to pregnenolone dosing. There are many pregnenolone products on the market which have dosages around the 100 mg mark. Thus, it is understandably confusing that we came out with a product dosed 20 times lower, at 5 mg! There is a very good reason for this though.

If we take a look at figure 1 again, we see that pregnenolone can convert to a large amount of steroid hormones, however, it achieves this through intermediary steroid hormones. The first two conversions are to progesterone via the enzyme 3β-hydroxysteroid dehydrogenase (3β-HSD), and 17α-hydroxypregnenolone via the enzyme 17α-hydroxylase. After this initial conversion, the path we are most interested in, is the path that 17α-hydroxypregnenolone takes. 17α-hydroxypregnenolone converts to dehydroepiandrosterone (DHEA) via the enzyme 17,20-lyase. DHEA can then convert to two different compounds, which both are direct precursors to testosterone. The first of which is androstenedione, which is generated from DHEA by the enzyme 3β-HSD. The second of which is androstenediol, which is generated from DHEA by the enzyme 17β-Hydroxysteroid dehydrogenases (17β-HSD). This is where things get exciting, because at this point, androstenedione converts to testosterone via the enzyme 17β-HSD, and androstenediol converts to testosterone via the enzyme 3β-HSD. So, it would seem logical that pumping more and more pregnenolone into these pathways would then yield increasingly more testosterone. However, that’s where things get tricky!

As the supply rate of pregnenolone increases, the synthesis of all steroid hormones goes up significantly. The problem with this, is that these steroid hormones can actually inhibit the steroidogenic enzymes as they start to increase in concentration. Thus, increasing the supply rate of pregnenolone will then lead to progressively more steroidogenic enzyme inhibition. Research has indicated that the outcome of this gradual steroidogenic enzyme inhibition gradually starts to favor progesterone synthesis from pregnenolone, rather than androgen synthesis. The further away the steroid hormone is from pregnenolone in steroidogenesis, the quicker their synthesis is going to be halted by enzyme inhibition. This means that the first steroid hormone to see its synthesis rate drop with higher supply rates of pregnenolone, is androstenedione, the direct precursor to testosterone, and likely one of the most important ones too. We’d then also see androstenediol synthesis follow a similar pattern of decreased synthesis. The next to see its synthesis levels drop, would then be DHEA, after which 17α-hydroxypregnenolone follows. This is where things really take a turn for the worse, because it appears that the conversion of pregnenolone to progesterone just keeps trucking right along, no matter what the supply rate of pregnenolone is!

The TL;DR version of the above, is that when we escalate pregnenolone doses, we don’t appear to see a linear increase in all of the steroid hormones. Instead, increasing pregnenolone doses actually just results in more progesterone being synthesized, with the synthesis of androgens gradually leveling out. This is pretty much the exact opposite of what we want to achieve, and thus, lower doses seem to make more sense. While the exact perfect dose is unknown, 5 mg seems fairly ideal to us. One of the reasons for this, is the high lipophilicity of pregnenolone, meaning that even low doses should have a high impact on the cellular levels of pregnenolone. The other reason for this dose, is a little bit more unscientific.

On various forums online, individuals have noted over the years that low doses of pregnenolone produced a slew of classic androgenic effects, such as increased libido, confidence and physical strength, whereas higher doses actually appeared to produce opposite results. I (ND product specialist), experienced this myself too. In fact, I experienced this totally by accident! I had been taking 5 mg pregnenolone tablets for a few months with fantastic results, and it was once again time to re-order. For some reason, I completely missed that this time, I had accidentally ordered 50 mg tablets instead of 5 mg tablets. I also didn’t notice this when I started taking the pregnenolone from this bottle, because it looked exactly the same as my 5 mg bottle. After a week, I really started to feel off and sluggish, and couldn’t really figure out what was going on. Then one morning, I took a closer look at my pregnenolone bottle, and realized I had been taking 50 mg instead of 5 mg! I stopped taking the 50 mg tablets, and gradually started to feel better. Then after about a week, my bottle of 5 mg tablets arrived, and I started taking this dose again, which yielded the same wonderful results again. During beta-testing, we paid attention to this interesting biphasic effect of pregnenolone, and we once again noticed that 5 mg just seemed to provide the all around best effect.

Thus, even if the urge arises to go for a higher dose of pregnenolone, keep in mind that this may not achieve exactly what you want. Just like with melatonin, some things simply are just better when they are dosed lower!

A Delightful Brain Modulator

The unique thing about pregnenolone, is that it is also a neurosteroid, meaning that it has significant effects in the brain. This is very interesting, when we consider the high lipophilicity of pregnenolone, which means that it can very easily pass into the brain via the blood brain barrier (BBB). Once in the brain, it pulls off a very special trick that not a whole lot of compounds have the ability to do, it activates the sigma-1 receptor! This is a bit of a holy grail target within the nootropics community, so finding a good sigma-1 agonist is always very exciting. However, what exactly sigma-1 is doing, is still a little bit unknown but recent research has started to show a relatively clearer picture of its various functions. One of the biggest effects nootropics enthusiasts are going to be after with sigma-1 agonism, is its beneficial effects on neuroplasticity by enhancing both nerve growth factor (NGF) and brain derived neurotrophic factor (BDNF) activity. This likely also underlies sigma-1’s ability to modulate mood. However, this could also be due to the fact that sigma-1 appears to modulate the activity of lots of neurotransmitters, such as dopamine, serotonin, GABA, glutamate and even norepinephrine. In fact, it almost seems like sigma-1 acts as a bit of thermostat control, allowing fine tuned control over various different neurotransmitter systems!

Pregnenolone also has another trick up its sleeve, by acting as a precursor for another potent neurosteroid called allopregnanolone. Pregnenolone converts to allopregnanolone via an intermediary step which involves progesterone. Going back to figure 1 again, pregnenolone converts to progesterone via 3β-hydroxysteroid dehydrogenase (3β-HSD). Progesterone then converts to 5α-dihydroprogesterone, via an enzyme that may be familiar to a lot of you, called 5α-Reductase (5-AR). This is the same enzyme that converts testosterone to dihydrotestosterone (DHT)! Finally, 5α-dihydroprogesterone is converted to allopregnanolone via 3α-Hydroxysteroid dehydrogenase (3α-HSD).

Allopregnanolone is a very unique compound, because it acts as a relatively potent positive allosteric modulator of the GABAA receptor. What this means is that allopregnanolone can make GABAA receptors more sensitive to the neurotransmitter GABA. The overall result of this is a fantastic calming effect. Similar to pregnenolone, allopregnanolone also appears to have beneficial effects on neuroplasticity. Combine this with the unique sigma-1 agonist and hormone support effects of  pregnenolone, and you end up with a very unique mood boosting nootropic effect!

Stacking With Pregnenolone

Pregnenolone is also a very versatile compound to stack with, and can help glue together lots of different stacks. The most obvious stacks of course involve supplements that have effects on our hormones, such as tongkat ali, cistanche tubulosa, and tribulus terrestris. However, pregnenolone works just as well in mood boosting and nootropic stacks. For example, pregnenolone via its conversion to allopregnanolone, can help bolster the effects of GABAergic supplements such as lemon balm or GABA. Pregnenolone, via its sigma-1 agonism, can also help round out stacks which involve monoaminergic supplements, such as saffron, or sabroxy. 

Overall, there certainly is no shortage of stacking potential with pregnenolone, so to get the ball rolling, here are some stacks we put together with pregnenolone! These stacks are fantastic picks if you want a ready made stack, however, they can also serve as a source of inspiration, if you want to design your own personalized stack.

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