Panaxatriol - Ginseng Constituent Has Protein-Anabolic Effects When It's Administered After Resistance Training

Warning: It's too early to stockpile ginseng or ginseng capsules, yet... the independent jury is still out there.

Ginseng is not exactly the agent you will think about when you hear the word "natural anabolic". And in fact, previous studies using whole ginseng or extracts that were usually standardized for ginsenosides shown to help with dementia in athletes were not exactly encouraging.

Against that background, I have to warn you right away (I will repeat my warning in the conclusion) that you should not rush to the next best supermarket or supplement store to get a bag of ginseng roots or pills.

Why's that? Well, you cannot be sure that they contain enough of Panaxatriol, which is the active ginseng saponoid that worked the muscle building magic in the latest sponsored proof-of-concept study from Japan. A rodent study (another reason not to literally buy into the hype, yet), yes, albeit one with results I consider worth reporting... if nothing else, because I expect this agent to be part of yet another kitchen-sink "natural anabolic" supplement in the near future.
So what do you have to know? Well, it has long been known that the anti-hyperglycemic mechanism of ginseng involves upregulation of Akt signaling and that it owes its nerve-regenerating effects to an upregulation of ERK1/2 signaling. Since these proteins also figure in skeletal muscle protein synthesis, it was only logical for Takamura et al. to assume that "ginseng could increase muscle protein synthesis via the Akt-mTORC1 or ERK1/2-mTORC1" (Takamura. 2016).

Since previous studies suggested that the Panaxatriol saponins are responsible for the effects on Akt and ERK1/2, it was only logical for the Japanese researchers to use isolated panaxatriol saponins, which have an excellent bioavailability, because the interaction with the gastric acid and the enzymes of intestinal bacteria cleaves the branched-chain sugars from the saponins and turns them into active Panaxatriol (PT), in their study. A study on Sprague-Dawley rats, whose legs were divided into control, PT-only, exercise-only, and exercise + PT groups. As the authors explain, "[t]he right legs were subjected to isometric resistance exercise using percutaneous electrical stimulation, while the left legs were used as controls" (Takamura. 2016).

Figure 1: Effects of PT on rpS6 phosphorylation at Ser240/244 0.5 h (A) and 3 h (B) after resistance exercise (Takamura. 2016); Con, control; EX, exercise; PT, panaxatriol; A.U., arbitrary unit

Interestingly enough, the isolated PT was administered only once and after the "workout" at a dose of 0.2 g/kg - 30 mg/kg for a human being (so ~1.8 - 3g of Panaxatriol) and yet it had the effects the scientists had expected: the treatment did not just elevate the Akt and ERK1/2 phosphorylation in the PT treated animals significantly over the exercise-only group, it also triggered highly significant elevations of the downstream controller of muscle protein synthesis, p70S6K, which was significantly increased at both 0.5 h and 3 h after exercise.

Figure 2: Effects of PT on muscle protein synthesis 3 h after resistance exercise. Representative images of western blot analysis with anti-puromycin (Takamura. 2016).

Now you may rightly be arguing that this is all nice, but irrelevant. After all, it's the actual protein synthesis that counts, not the elevation of regulatory proteins. Indeed, you're right, but by the means of the relatively new, but tested SUnSET method (Goodman. 2013), Takamura et al. were able to detect a significant increase in protein synthesis in the rodents that received the PT supplement immediately after their "workout".

The extent of the increase, however, cannot be accurately quantified by this method. Accordingly, we know that the increase in the protein synthesis gauge p70S6K actually triggered increases in protein synthesis, but we don't know if the effect size of this increase was practically relevant.
References:

• Goodman, Craig A., and Troy A. Hornberger. "Measuring protein synthesis with SUnSET: a valid alternative to traditional techniques?." Exercise and sport sciences reviews 41.2 (2013): 107.
• Takamura, Yusuke, et al. "Panaxatriol derived from ginseng augments resistance exercised–induced protein synthesis via mTORC1 signaling in rat skeletal muscle." Nutrition Research (2016).