L-Carnitine L-Tartrate vs. PLCAR

[MAxximal]

Androgen Receptor Up-Regulation Introduction

By: MuscleTech


The influence of testosterone (T) on skeletal muscle protein synthesis is mediated by the androgen receptor (AR). T binding to the AR converts the latter to a transcription factor; the T-AR complex then translocates to the nucleus and associates with DNA to regulate androgen-specific gene expression.1
Animal and clinical studies indicate that the AR signaling pathway is required for appropriate development of skeletal muscles, since it regulates increases in lean muscle mass, muscle strength, and muscle protein synthesis. The physiological importance of AR for muscle protein accretion has been demonstrated, as muscle hypertrophy is attenuated by AR blockade.2

Effects Of Exercise On AR

Several human and animal investigations have researched the physiological importance of the AR in exercise-induced muscle hypertrophy,1-8 emphasizing the importance of exercise at increasing the AR content,1-3,5,6 seemingly in a fiber-specific manner.4


Resistance exercise (RE), for instance, elicits a significant decrease in AR content in type-I slow oxidative, and a significant increase in type-IIb fast glycolytic fibers.4
Type-IIb fibers are those white fibers, also referred to as fast twitch B or fatigable fibers, that are most beneficial in sports such as sprinting. These fibers have low myoglobin content, few-mitochondria, and few blood capillaries, but contain a large amount of glycogen - these muscles primary source for energy during short, intense bursts in activity.


In untrained men, a single bout of heavy RE has been reported to up-regulate AR mRNA 48h post-training.3,6 Repeated RE bouts (each separated by 48h) instead, have been shown to increase AR mRNA and protein expression.3
Such augmentation correlated with elevated serum testosterone levels and corresponded to significant increases in myofibrillar protein.3 Testosterone is the primary hormone that interacts with skeletal muscle tissue, and when elevated leads to increased muscle growth.

In trained individuals, high-volume high-intensity RE appears to cause a significant decrease in AR protein content (-46%) at 1h post-exercise, probably due to protein catabolism induced by exercise-related stress.5
Such a negative effect, however, seems to be somewhat mitigated by post-RE feeding, which has been shown to increase muscle AR content, resulting in increased testosterone tissue uptake and enhanced luteinizing hormone (LH) - which also has been shown to elevate testosterone levels - release via feedback mechanisms.1 These observations provide a possible mechanism for increased protein synthesis following post-RE food intake.

What Is Luteinizing Hormone?

Luteinizing hormone (LH, also known as lutropin) is a hormone synthesized and secreted by gonadotropes in the anterior lobe of the pituitary gland. In concert with the other pituitary gonadotropin follicle stimulating hormone (FSH) it is necessary for proper reproductive function.
[ wikipedia ]


Effects Of L-Carnitine-L-Tartrate Supplementation On AR:

L-Carnitine-L-Tartrate (LCLT) supplementation has been evaluated in RE-trained humans as an enhancer of the hormonal responses to RE and a recovery promoter.1,9,10
3-weeks supplementation with LCLT (equivalent to 2 g elemental carnitine/day) has been shown to reduce muscle damage produced by an acute bout of high-intensity RE in two cross-over, placebo-controlled trials.9,10 - the "gold standard" so to speak in terms of clinical trials.

According to the investigators, less muscle damage may have resulted in more hormonal receptors available for binding interactions with anabolic hormones,9 a circumstance that may explain the reduced progression of muscle damage (measured by MRI) in the recovery days following RE.9,10 With more hormonal receptors available for binding interactions with anabolic hormones, muscle growth potential is also increased.
In particular, one study has shown that 21-days LCLT supplementation (equivalent to 2 g elemental carnitine/day) in recreationally resistance-trained individuals induced a significant upregulation of pre-exercise skeletal muscle AR protein content [15.2% more compared with PL (12.9+/-5.9 vs. 11.2+/-4.0 au, respectively)] compared with placebo.1
LCLT may have worked by reducing muscle damage associated with RE,9,10 therefore attenuating the catabolism of muscle-specific proteins (including AR).1
As a consequence, LCLT may enhance testosterone uptake via less muscle damage and increased availability of AR, and not via direct stimulation of T secretion (in other words, LCLT is not a testosterone-enhancing supplement).1




Based on these considerations, and on the fact that post-RE feeding stimulates increases in AR content (see above),1 it is possible that LCLT and feeding may independently and synergistically enhance the hormonal environment following RE and promote anabolism.

Conclusions

In summary, research shows that:

Feeding after RE increased AR content, which may result in increased testosterone uptake, and thus enhanced luteinizing hormone secretion via feedback mechanisms.

L-carnitine supplementation can upregulate AR content, which may promote increased testosterone uptake and recovery from RE.
In layman's terms, such increases in anabolic hormones and with recovery being enhanced you can expect more muscle growth.


References:

Kraemer, W.J., et al. Androgenic Responses to resistance exercise: Effects of feeding and L-Carnitine. Med Sci Sports Exerc 38(7): 1288-1296, 2006.
Inoue, K., et al. Androgen receptor antagonist suppresses exercise-induced hypertrophy of skeletal muscle. Eur J Appl Physiol Occup Physiol 69(1): 88-91, 1994.
Willoughby, D.S., and L. Taylor. Effects of sequential bouts of resistance exercise on androgen receptor expression. Med Sci Sports Exerc 36(9):1499-1506, 2004.
Deschenes, M.R., et al. Endurance and resistance exercise induce muscle fiber type specific responses in androgen binding capacity. J Steroid Biochem Mol Biol 50(3-4): 175-179, 1994.
Ratamess, N.A., et al. Androgen receptor content following heavy resistance exercise in men. J Steroid Biochem Mol Biol 93(1): 35-42, 2005.
Bamman, M.M., et al. Mechanical load increases muscle IGF-I and androgen receptor mRNA concentrations in humans. Am J Physiol Endocrinol Metab 280(3): E383-390, 2001.
Tchaikovsky, V.S., et al. The effect of exercises on the content and reception of the steroid hormones in rat skeletal muscles. J Steroid Biochem 24(1): 251-253, 1986.
Lee, W.J., et al. Regulation of androgen receptor expression at the onset of functional overload in rat plantaris muscle. Am J Physiol Regul Integr Comp Physiol 285(5): R1076-R1085, 2003.
Kraemer, W.J., et al. The Effects of L-Carnitine L-Tartrate supplementation on hormonal responses to resistance exercise and recovery. J Strength Cond Res 17(3): 455-462, 2003.
Volek, J.S., et al. L-Carnitine L-Tartrate supplementation favorably affects markers of recovery from exercise stress. Am J Physiol Endocrinol Metab 282(2): E474-E482, 2002.

[wheels]

I will tell you what I am using, have been using for the past 8 weeks, and which I am having tremendous success with. My other daily recommendations are up, but for Intraworkout:

in a 32 ounce gatorade bottle -

1 flat tsp LCLT
1 flat tsp PLCAR
750mg Alpha-GPC
1 gram Taurine
3 grams Beta-alanine
2 grams calcium citrate
4 scoops Xtend
250mg Agmatine
1 capsule of Sline-sane (it's a Norvaline/Banaba/Gymnemma supp)

What about a combo of ALCAR and LCTL ?

[dsade]

What about a combo of ALCAR and LCTL ?

ALCAR will help somewhat with focus. Depends what you are going for. ALCAR taken after around 5:00 keeps me awake too late.

PLCAR has a higher affinity for muscle and cardiac mitochondria - hence my recommendation of it.

The Tartarate version is recommended merely because that is the only form with a conclusive study performed on it.

[BurghHardcore]

Dsade, where do you get your Alpha-GPC. I'm looking on Nutra now and see that NOW has it, but noone else. Could you point me in any certain direction?

That intra-WO stack of yours looks SICK!!!

[dsade]

Dsade, where do you get your Alpha-GPC. I'm looking on Nutra now and see that NOW has it, but noone else. Could you point me in any certain direction?

That intra-WO stack of yours looks SICK!!!

I ordered from Beyond-a-century.com

I'm contacting the supplier to try and get Nutra to be able to offer it in bulk. It's really incredible stuff.

[rottie76]

Yes, that'd be great!! I get mine from BAC as well and it's very good, high quality material unlike BN which didn't do squat for me..

[msucurt]

dsade....is this what you are ordering?

http://www.easycart.net/BeyondACentu...mins.html#1125

I ordered from Beyond-a-century.com

I'm contacting the supplier to try and get Nutra to be able to offer it in bulk. It's really incredible stuff.

[thescience]

the plcar at 3-4g a day increases sex drive in an insane manner; in my case this is painstakingly obvious in 3 days. its noted here that a spectracell test i took has me a high blood carnitine; for anyone who doesnt know it, spectracell claims to be a vastly superior measure of a range of nutrient levels dating back 6 months, as opposed to a blood test which tells you what youve got in your stream at the moment. anyway, my dramatic responce to the plcar in so quick a manner could in part be due to my naturally high levels, whereas someone starting lower may take longer to get there. in my opinion plcar is better than alcar with regards to sex drive and muscle energy. i discontinued both products, having taken neither more than 8 days because of the resulting loss of apetite. while this is favorable to many people perhaps, all the weight i gain turns into muscle mass, so im happy with my apetite. i would like to experiment with this substance further, as the dr wright protocal has people taking 4g a day without discussion of taking a break and, frankly, id like to see if there's a saturation point we can reach where the amount is too much. the site i studied advocating dr wrights protocal was claiming people in their seventies would maintain the same vibrant sex drive as ehen they were 20; having glimpsed at plcar's awesome power, im stashing this experience in my memory bank