glucocorticoid receptors

A Closer Look at Trenbolone

Not too many steroids have an air of mystique about them quite like trenbolone. It is one of those agents that you will hear talked up aggressively by some guy in the gym, to later find he has not even tried it himself yet. The bodybuilding literature is full of strong, unusual, and often-inaccurate statements about this drug, and consequently an air of misunderstanding has begun to cloud our view of trenbolone. The unusual history of this compound, including prolonged periods of very limited availability and high selling prices, has no doubt played a part in shaping the view of this steroid in the minds of athletes. It seems when anything is out of reach, overly expensive or both, people start looking at it in a different way. I therefore thought it would be a good idea to take a closer look at the physical properties of trenbolone, as well as its current state of availability and use.

Although derived from nandrolone, trenbolone is comparatively far more androgenic than this steroid. In fact it is several times stronger in this regard than our primary androgen testosterone as well. The first contributing factor to this of course is that trenbolone is a strong binder of the androgen receptor. This trait is also characteristic of its parent nandrolone, which is several times more active than testosterone in this regard. Androgen binding is in fact further enhanced by the introduction of double bonds in delta-9,11, which makes trenbolone an even more potent agonist of the androgen receptor than nandrolone. Perhaps more significant though is the fact that unlike nandrolone, the strong receptor binding potency of trenbolone is not diminished in androgen sensitive tissues by 5-alpha reductase. Trenbolone does not seem to undergo 5-alpha reduction in humans to any appreciable degree at all, which is evidenced by the fact that the major urinary metabolites of trenbolone all possess the original tri-en structure with an intact delta-4 group. So trenbolone retains its original potency as it enters cells in androgen target tissues with high 5AR concentrations, as this enzyme is not affecting it. These factors work together to allow trenbolone to be a potently androgenic steroid, instead of a primarily anabolic one in nature like nandrolone.

It has been reported in other bodybuilding literature that trenbolone does not exhibit any activity as a progestin in the body. I am not certain where this belief originated, as trenbolone does appear to exhibit the classic progesterone receptor binding ability that is characteristic of nandrolone and its derivatives. One study looking at the bovine uterine progesterone receptor for example found trenbolone to be a very potent binder, startlingly even more so than progesterone itself. Another looking at the binding of various compounds to the androgen, estrogen, progestin, mineral corticoid and glucocorticoid receptors found trenbolone to be a more potent binder of the progestin receptor than nandrolone, a steroid normally noted for its usual activity in this regard. What does this mean for trenbolone? I don’t think it really means that much. Trenbolone clearly doesn’t cause gyno, water retention or fat buildup, which one might attribute to estrogenic or progestational activity. So whatever slight action it does have as a progestin on paper doesn’t amount to all that much in the real world. The absence of estrogen may be a significant factor, as progesterone is believed to cause gyno by enhancing estrogen’s stimulation of mammary gland growth. Perhaps when trenbolone is taken with other aromatizable compounds it could affect a person’s sensitivity level to gyno and water/fat retention. This seems logical, at least in a technical sense, although admittedly I have seen no evidence to support this.

Mass or Cutting Agent
The potently androgenic and non-aromatizing nature of trenbolone makes it an extremely effective hardening and cutting agent. In fact, it is thought of as unmatched in its capacity as a body-sculpting steroid. Many competitive bodybuilders similarly find it indispensable to any good pre-contest cutting stack. For this type of purpose I doubt another steroid would serve you better. Many people do additionally find they make very good muscle gains with trenbolone. It is a potent muscle-builder, although we should probably not consider it an ideal mass-builder when used alone. The absence of estrogen is an important factor, as this trait seems integral in this type of steroid. This probably has to do not only with water retention but also interactions between estrogen and muscle glucose utilization, GH release and androgen receptor proliferation. Today we are finally starting to understand why this hormone is needed for optimal growth. Trenbolone is probably still the most potent muscle-building agent of all the non-estrogenic steroids though, and admittedly is quite unusual in its potency in this regard. But I would still think that if mass were the goal and you were choosing only one steroid, testosterone, Dianabol or Anadrol would be more productive every time in terms of overall size, weight and muscle mass gain.

As mentioned in the opening of this article, trenbolone has been plagued by periods of manufacturing inconsistency, high prices and scarce availability since it first hit the market in the early 80’s. There is probably little need to revisit in detail the rise and fall of Finajet in the 1980’s, or the demise of Parabolan in 1997. Clearly the colorful history of trenbolone is well discussed. But today’s situation is no less interesting, as we are in a unique situation. For the first time in four years we have a legitimate injectable trenbolone again, as the Mexican veterinary drug firm Laboratories Ttokkyo has recently started producing Trenbol, a 10 ml bottle of trenbolone acetate (TA) in the strength of 75mg/ml. This product is not cheap, and usually sells for upwards of $150 a bottle. Reportedly Denkall is working on a similar item, and there are some reliable underground generics floating about as well that sell for a better price and usually supply a comparable amount of TA. There have been some questions about raw material supply lately though, and whether or not both types of product would remain on the market. This discussion was heightened by the recent removal of Trenbol from Ttokkyo’s website, which is making a lot of people nervous that this product may be on the way out. Hopefully this is just a website problem and not a repeat of the fate that fell on Finajet and Parabolan. If these products do dry up, trenbolone will still be available, but in the form of cattle implant pellets. In Part II of this article I will take a closer look at these unusual products, as well as the various methods utilized by bodybuilders in an effort to effectively use them.

anonymous asked:

Hi, Koryos! I was wondering if you have any insight on why animals enjoy petting so much? As a person, I personally don't like the feeling of being petted. Is it just that I'm soothing little itches for them, or something else?

Good question! The answer is quite complex, actually, starting with the fact that animals don’t always like to be petted, either. Of course, everyone probably knows this, and has experienced times when their pets have acted uncomfortable with physical contact. 

Petting, as a matter of fact, is a very specific type of touch. It’s different from poking, patting, or pinching. And I do mean literally different: gentle stroking on the skin actually activates different neurons than other forms of contact do. So petting isn’t just an arbitrary category- it’s a form of contact most mammals are primed to perceive differently.

Activating the “petting neurons” (called MRGPRB4+ fibers in the scientific literature, but let’s stick with “petting neurons”) feels good. In one study, researchers let mice choose between two chambers- one they preferred, and one they didn’t- and then activated the petting neurons in the non-preferred chamber. The mice went to that chamber as soon as they learned it would activate those neurons, and showed fewer stress responses to boot, entering a state of soothing mouse bliss.

Petting neurons occur on hair-covered areas of the skin, so the general consensus is that these neurons evolved to help give positive feedback to grooming behaviors. In other words, the act of cleaning our fur or hair feels good, which motivates us to keep cleaner and healthier fur or hair.

However, there’s another, additional reason animals enjoy being petted: social grooming, or allogrooming. Allogrooming occurs when one animal grooms another. Not only does this activate “petting neurons,” it also generates the release of the hormone oxytocin in both the groomer and the groomee. Oxytocin, among other things, can foster a feeling of connectedness and closeness between two individuals and is critically important for animals that form close pair-bonds. Social grooming also results in the release of pleasure-inducing endorphins, and inhibits the release of corticosteriods  (i.e., stress hormones). 

In fact, social grooming is so important for young mammals that those that are deprived of tactile contact when very young end up with abnormal concentrations of serotonin and TSH, both of which help manage the release of corticosteroids (those stress hormones again!). These animals- and humans- go on to be unusually anxious and asocial adults.

So, to sum up: petting activates specific neurons associated with pleasure, relaxation, and bonding, which is why so many animals appear to enjoy it. However, as I mentioned before, even if you’re doing the right kind of petting (not patting or tickling), animals don’t always enjoy the experience. Context matters very much, and if an animal isn’t in the mood to be petted, or doesn’t like to be touched in a particular area, it won’t matter how well you light up those neurons: they’re still going to hate it. Pay attention to what their body language is telling you.


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Liu, Q., Vrontou, S., Rice, F. L., Zylka, M. J., Dong, X., & Anderson, D. J. (2007). Molecular genetic visualization of a rare subset of unmyelinated sensory neurons that may detect gentle touch. Nature neuroscience, 10(8), 946-948.

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