Tuesday, 2 September 2014

Fat cell size regulation

Thanks to Bill for sending me this paper....

The premise of the paper is this......

Since individual cells from freshly isolated white adipose tissue (WAT) exhibit variable levels of fat accumulation, we attempted to determine which factor(s) cause this variation.

If you look at those micro-scope pictures of adipocytes from adipose tissue, youll notice that they are not all exactly the same size.  ( see here for ex ). Below is a distribution count of rodent adipocytes isolated and exposed to growth  + adipogenic media....

Cells were divided into a "high" and "low" category according to their BODIPY staining which was closely related to their size and therefore how much fat they stored.

As you can see from the top graph, you get an approximate normal distribution. But the question is why? Why arent adipocytes all the same size?

In general adipocytes from the same localized region of the body are exposed to the same concentrations of nutrients in the blood ( or there abouts ) and therefore CICO should predict for them to be roughly the same size. But they arent.....   therefore this can only mean there is a property intrinsic to the adipocyte that determines its size......

Now... if you want the TL:DR point of this post... it is this......

The extent of fat accumulation is correlated with histone acetylation of the Ppar promoter that is heritable and maintained even in dedifferentiated adipocytes.

What this means in plain english is, that if you take a bunch of adipocytes and expose them to growth media and adipogenic media, leave them to incubate for a few weeks, then examine them under a microscope, they are NOT all exactly the same size, even though they were all exposed to the exact same conditions. 

If you snoop around a bit more, youll find the thing that determines how "fat" an adipocyte gets is correlated with the histone acetylation of the PPAR-gamma gene. "histone acetylation" is how biology does gene regulation, I.E. how strongly a gene is expressed. As the paper says....

Histone acetylation is generally correlated with transcriptional activation

So a gene with a high histone acetylation will have a high transcriptional activity and be expressed strongly within the cell. Overall this is just a fancy way of saying, a fat cell has a "set point" for the amount of fat it will store that is dependent on the genetics of that cell.

To understand how I can make that statement, you need to go back all the way to this post...in which we learned that PPAR-gamma plays a huge role in determining how much fat you store.  Now we can understand a bit better why there is *some* truth to the idea of a fat/weight "set point", .

Each individual fat cell in your body has a fat/weight set point, that is determined by the histone acetylation of the PPAR-gamma gene. And your total body fat mass is just the sum of the fat mass of all your individual adipocytes...... therefore YOUR fat mass has a "set point".....unless you grow new adipocytes, in which case your fat mass "set point" goes up

This helps explain why people with more fat cells are generally fatter.

The following graphs show some of the characteristics of the fat cells before and after exposure to growth media....



Interestingly, the insulin receptor expression was not different between fat cells that ended up being small or large.....

This would suggest that it is post-receptor signalling that is involved in the "insulin sensitivity" of a fat cell.  Indeed you could say that large fat cells achieve their inflated sizes by having elevated expression levels of PPAR/GLUT4/SREBP1c.

I was especially interested in the GLUT4 graph, because I have seen previous evidence that GLUT4 is very anabolic for fat tissue. GLUT4 over-expression on adipocytes results in gross adipocyte hyperplasia, and that hyperinsulinemia selectively increases GLUT4 on adipocytes and reduces it on muscles.

Anyway, im not sure what controls GLUT4 gene transcription in adipocytes, I think PPAR-gamma is involved since Thiazolidinediones, which are PPAR-gamma agonists, increase GLUT4 on adipocytes. 

This study demonstrates that subpopulations reside within WAT and 3T3-L1 cells that vary in their capability to accumulate fat and that these differences are heritable. We have shown that the extent of the cell’s ability to accumulate fat correlated positively with expression levels of Ppar , a master regulator of adipogenesis, and with other markers of differentiated adipocytes, including Lep, Tshr, InsR, Glut4, Fasn, Srebp1c, aP2, and Pref1; exogenous expression of Ppar in 3T3-L1 cells increased fat accumulation; and the levels of histone H3 acetylation of the Ppar promoter in preadipocytes was a predictor of the extent of fat accumulation upon induction of adipogenesis.  
We thus suggest that epigenetic modification of the Ppar promoter is, in part, the mediator of the heritability of adipocyte differentiation.

With respect to the bolded sentence, "exogenous expression of Ppar in 3T3-L1 cells increased fat accumulation", do you remember how to increase Ppar in vivo?......... Insulin.

I do also wonder about the implications of the epigenetic modifcation of the histone acetylation of Ppar and the coincidence of fat mothers ( parents ) giving birth to fat babies.










Monday, 25 August 2014

Metformin mechanism of action

In the last post I linked to a study proposing that insulin mainly causes triglyceride accumulation by inhibiting fat oxidation. From 2006 there is another study detailing how metformin counters the ability of insulin to inhibit fat oxidation.

How does insulin stop fat burning? Theres a few ways this happens, and one of the ways is by increasing  malonyl-CoA. Insulin activates the enzyme acetyl-CoA carboxylase ( ACC for short ) that converts acetyl-CoA to malonyl-CoA,  (link)

malonyl-CoA in turn inhibits carnitine palmitoyltransferase (CPT) I, the enzyme that controls the transfer of long-chain fatty acids  into the mitochondria where they are oxidized (link). So essentially the enzyme ACC is the cellular switch between fat burning and fat making/storing. ( there are probably other cellular switch's aswell )

Controlling the enzyme ACC is therefore probably central to cellular energy dynamics.

If we turn off the ACC enzyme, we can stop making fat and start burning it instead........so how can we turn it off? Thats where metformin and AMPK enter the picture. AMPK directly shuts down ACC, by phosphorylation at several serine sites. AMPK responds to increased cellular levels of AMP, and we can activate AMPK by doing things like fasting, exercise, low-carbing, vinegar, acetate fermentation in gut from fibre,....... and probably most importantly, KEEPING INSULIN DOWN.

While none of this stuff is particularly new to seasoned researchers, what is "new-ish" is a 2013 study  that looked at changing the serine phosphorylation sites on the ACC enzyme to alanine. This now makes ACC highly resistant to inhibition by AMPK, allowing relentless lipogenesis and lowered fat oxidation. The result is that the rodents with these alanine knockin enzymes become very insulin resistant with fatty liver, and metformin DOESNT work on them.

What this shows is that the primary way metformin improves insulin sensitivity is by curbing the activity of the ACC enzyme.

There are a few corollaries here aswell....

- the rodents in the alanine knockin study didnt become obese even though they had reduced fat oxidation. This would *seem* to contradict the idea that insulin causes fat gain by lowering fat oxidation. However keep in mind that we are dealing with 2 studies that did completely things. In study 1 excess insulin was pumped into the rodents, and in study 2 the ACC enzyme is made mutant. It should go without saying these are certainly not equivalent. There are other ways insulin inhibits fat oxidation not to mention insulin does significantly more when it binds to adipose tissue other than just lowering fat oxidation/activating ACC.

- Increased basal malonyl-CoA levels have been found in muscle from obese and T2D subjects (link). They also found that the activity of the ACC enzyme was much higher in the basal state in these subjects. This brings me back to the idea of obesity/T2D being caused by excess insulin secretion, in particular fasting hyperinsulinemia. Alot of people seem to be under the impression that insulin secretion is primarily reactive to insulin resistance, and that insulin resistance appears FIRST and increased insulin secretion is compensatory. 

If metformin improves insulin sensitivity by curbing the ACC enzyme, and increased levels of malonyl-CoA and ACC activity are found in muscles of obese/T2D subjects, doesnt this suggest the insulin resistance is caused by the increased malonyl-CoA and ACC levels?

And what causes increased malonyl-CoA and ACC? ........ insulin!

Its *unproven*, but makes sense..... increased fasting insulin secretion -> increased fasting malonyl-CoA and ACC, -> resistant to insulin.

- sometime ago I made a post on carbohydrate-sensitive obesity. In that model we saw that sensitivity to carbohydrate induced obesity was predicted by having overly suppressed fat oxidation in the postprandial state. With respect to metformin stopping insulin from lowering fat oxidation, I would like to speculate that metformin may help prevent carbohydrates from making you fat by keeping fat oxidation elevated in the postprandial state. I would also speculate there are genetic differences in the ability of insulin to inhibit fat oxidation because the sensitivity of CPT1 and ACC can be influenced by genetics.

- Lastly, muscle IR is not the only defect in obesity/T2D, there is also hepatic IR and excessive glucose output that we think is primarily driven by hyperactivity of the FOXO1 transcription factor manufacturing the PEPCK enzyme. Read this comment here to learn how this ties in with all of the above.







Saturday, 19 July 2014

*How* does insulin cause weight gain?

The question of exactly how insulin causes weight gain is not intuitively obvious enough and so it needed testing, and thats exactly what this paper did....

Adipose Weight Gain during Chronic Insulin Treatment of Mice Results from Changes in Lipid Storage without Affecting De Novo Synthesis of Palmitate

They infused mice throughout the day with mini-pumps containing extra insulin. This lasted for 7 days until the mice were sacrificed and their fat stores examined. All mice were put on a low fat chow diet.

First to note, is that there was a non-significant increase in food intake in the insulin treated mice, although there was a slight trend to the upside.

LI= low insulin group,  HI= high insulin group

Surprisingly they did not detect any increase in the de novo synthesis rate of palmitate in the insulin treated groups. So the lipogenesis pathway was essentially unaffected by the insulin treatment. This could have been because the palmitate de novo pathway was already running at maximum capacity, amoung other possible reasons they present in the discussion.

Second, the insulin treatment mice had a persistent decrease in their blood sugar levels, this may have been what caused them to eat *non-significantly* slightly more.

Did the insulin treated mice increase their fat stores? yes....



Only the increase in the high insulin group's fat stores was deemed statistically significant. The punchline however is that the newly formed fat in the high insulin group came almost exclusively from newly synthesized triglyceride ( subQ depot ).  There was a slight decrease in lipolysis as well which also contributed to the net fat gain.

 Our findings indicate that insulin treatment likely reduced whole body fat oxidation rather than increasing de novo fatty acid synthesis, and altered TG deposition and lipolytic rates in different depots, but the whole-body macronutrient energetics responsible for insulin-induced increased gain in weight and adipose fat remain to be fully explained.

So... there you have it. Atleast in this model. Insulin causes fat gain by diverting fatty acids that would otherwise have been oxidized for energy to instead be assembled as triglyceride and deposited into your adipose tissue.

The applicability of this to real life weight gain in humans is (probably ) not a straight forward translation,, but I think you can rest assured that, in situations of large amounts of insulin floating around, your likely to find excess triglyceride accumulating in your subcutaneous fat.

Is our food more insulinogenic now than it was 50 years ago? And is everyone carrying more triglyceride than we were 50 years ago?.....................






Monday, 26 May 2014

Dieting update

Ive been having quite a bit of weight loss success recently, love handles have gone down a bit and waist looks tighter, also people have been giving me complements that I look "healthy".

I still have fat to lose and it is all subcutaneous fat, which is murder to get rid of. But here's what im doing at moment

Melanotan II - Ive had to stop this completely because im very dark now and get weird looks from everyone in the street.

Clenbuterol - 20-40mcg per day, im using this because I need an edge to get rid of the stubborn subcutaneous fat and especially the love handles that have higher alpha receptors. I dont really like using Clen because the sides are pretty intolerable, MAJOR headache, shaky, anxiety,, jittery etc. But hey, it works.

CJC1295 with DAC - this is a growth hormone promoter, im just experimenting with it at the moment, been on it 4-5 weeks which is probably still a bit early to talk about results.

Nicotine Gum - 4-8mg per day, mainly to help shed the fat. I havent found nicotine gum to be addictive at all. If I go without it for a few days I feel absolutely no urge to use it. Works well as an appetite suppressant.

Diet - this is the thing that has made the biggest change. Ive made up my mind to stick with a cyclic keto diet. 6 days per week will be ultra low carb, only cheese,cream, meat, seafood, vegetables, avocado,  nuts, eggs. whey, butter. Some strawberries or raspberries if im feeling a slight sugar craving.

1 day per week I do ultra high-carb BUT low fat. My carb sources have been mainly banana, honey, beans, potatoes.   Infact I do about 12 banana's during my carb re-feeds, dipped in honey.   I try to keep the carb sources clean and stay away from the dirty carb's like bread, pizza, doughnuts etc. As I said, I think its key to keep fat low during the carb refeed, So its just whey, lean meats, and carbs.

If we look at the graph below, we see that the co-ingestion of carbs with fat causes a huge spike in the intestinal hormone GIP which is known adipocyte insulin sensitizer.



So ideally, you dont want to spike your GIP through the roof and insulin sensitize all your fat cells so much. Although there is no comparison to protein + carb in this study graph so im making a bit of a guess that its not as high as with fat, but fat is known to be the strongest promoter of GIP secretion.

During my low carb days I usually make breakfast 50g whey, 50g coconut oil, 4 tablespoon vinegar.  All these have been shown to reduce waist circumference and if there's one thing everyone should take on board its that getting a tiny waist is paramount to your physical attractiveness.

Another thing I want to comment on is that LC, or rather low insulin, seems to upreglate beta-receptors. I noticed after a few days of almost zero carb im extremely sensitive to clen, also side effects of clen seem to vanish as soon as you eat something that spikes insulin. Indeed there is a study floating around out there showing that beta-receptors become phosphorylated only 30mins after insulin exposure.



Wednesday, 7 May 2014

The problem with introverts

Having recently come from a holiday with my family where most of them are highly extroverted ( my cousin and his gf are super extroverts ) it kind of occurred to me what the main difference between the two is.

I have noticed when I am in a large group or in particular, with a strong extrovert, my brain shuts down. Ive seen alot of other introverts report this aswell. If you google search this topic you will also find similar testimonials, of introverts being unable to speak/think in the presence of ( strong ) extroverts. On these googled websites they will tell you some pseudoscience rubbish that introverts are "sensitive" to dopamine. And that too much dopamine "shuts" your brain down.

Here's what I think is happening......

If we remember from sapolsky's texts, dopamine is involved in the "pursuit of reward". Even better, I think its fairer to say that dopamine is a "do it" and "action/reaction" driving neurotransmitter.

When an organism receives a stimulus from the environment, the magnitude of the dopamine spike in response to that stimulus determines the magnitude of the reaction that the organism makes to that stimulus.

So, the problem with introverts is that the random small talk bullshit that extroverts like to spew forth doesn't cause a dopamine spike in an introverts brain, and thus the response from the introvert is either very short/breif/dull/boring.

Its not that your introverted brain is "shutdown". Its that the pointless banter of the extrovert doesn't stimulant it.

Its not that introverts are "boring", but rather Introverts like to talk about stuff that interests them, stuff that is meaningful, has logical purpose, is relevant to our survival, or conducive to success and improved quality of life.  That is what they dopamine spike to.

If you as an extrovert ask me a question to which I return a vacant blank stare and dull short response, its because im too polite to say "stfu , im not interested in that irrelevant shit"

There is no willpower, or conscious thought, involved in dopamine spikes, they are completely involuntary responses, and so your instinctual urge of how to respond is also pre-programmed and involuntary.  "boring" or "dull" has nothing to do with it.

Another problem with introverts is there brains are less likely to retain information that is not helpful for their survival or future success. This is an additional reason why small talk with introverts is hard because they dont care to remember WORTHLESS fucking details.





Saturday, 26 April 2014

Fat Digestion explained

Here is a lovely text detailing how fat digestion is handled.

Its worth reading the entire text but in summary ....

1 )  Eaten fat ( triglycerides ) is acted on by lipases in the GI-tract which split it into free fatty acids.

2 ) free fatty acids are absorbed by the enterocytes  ( cells of the GI tract )

3) enterocytes partition the fatty acids into different fate's, one of which is package onto a chylomicron

4 ) the chylomicron's are released into the systemic circulation where they float around and eventually interact with lipo-protein lipase in the endothelium of the various organs, one of which is adipose tissue. LPL then begins to break down the triglyceride from the chylomicron's into free fatty acids.

5 ) the presence of chylomicron's in the adipose tissue blood vessels also stimulates the release of ASP, acylation-stimulating protein  from adipocytes, which helps shuttle free-fatty acids liberated from chylomicrons by LPL into the adipocyte.

6 ) free-fatty acids that not are shuttled into the adipocyte escape and enter the systemic circulation, where they become part of the serum FFA pool. This contribution can be anything from 5-35% of the total serum FFA concentration.

7 ) once inside the adipocyte, free-fatty acids are once again packaged up into triglycerides, and are assembled into small lipid droplets in the endoplasmic reticulum.

8 ) the smaller lipid droplets are then acted on by lipid droplet proteins like FSP27 which fuse smaller lipid droplets into larger ones, eventually combining them with the large central lipid droplet present in the adpiocyte, at which point the fat can now be considered "body fat".

You should of noticed by now that there was no mention of insulin anywhere. So yes, dietary fat can be stored as body fat "without" involving insulin. But its worth noting that the stimulation of ASP by chylomicron's is enhanced in the presence of insulin ( link )

I expect that in the absence of high insulin levels, more of the fatty acids liberated from chylomicron's "spills" over, escaping adipocyte trapping and entering the systemic serum FFA pool. I remember from one of peter's post he mentions that high serum FFA = high energy expenditure, provided ofcourse again we keep insulin low since insulin inhibits fat oxidation.

So at this point one must be wondering, does this mean eating lots of fat and calories even without insulin stimulating carbs, we can get obese? I have doubts about this. The fact that chylomicron's stimulate ASP ofcourse is the ultimate evidence that we dont need ( elevated ) insulin to store dietary fat as body fat. The problem is this..... obesity is so much more than just "excess" triglyceride stored in adipocytes. I think all we can say is that eating alot of fat and calories will likely result in a *bit* of weight gain, as sam feltham proved.

Indeed I do not know of any studies of over-feeding keto in normal lean humans, only to follow them up several years later and find they maintained the elevated fat mass and are resistant to weight loss, both key features of the "obesity " phenotype.

Also of mention is that, although chylomicron's directly stimulate fat storage via ASP induction, researchers do not use chylomicron's in culture when attempting to cause preadipocytes to differentiate into mature adipocytes. They do however, use insulin and glucose.








Monday, 21 April 2014

GLUT4 over-expression in muscle = ????

Quick post.

What happens if you over-express GLUT4 in fast twitch muscle?

( for the record, the over-expressing mice appeared to have about 150% increased basal and insulin-stimulated GLUT4 expression )



Answer: You get a mouse that eats 45% more food than controls but weighs slightly less than them aswell!   Not only that, the over-expressing mice seemed to be quite fond of exercise, with a reported fourfold increase in voluntary wheel running..  So........... theres something about disposing of alot of glucose into muscle that makes you want to move.

This really makes me wonder about the association of obesity and laziness. Reduced GLUT4 on muscle partitions calories towards FAT.   We could hypothesize here that the reduced GLUT4 on muscle not only makes you lazy, but fat aswell. Its a double whammy.

I recently posted how, some weeks ago when I re-started melanotan-II injections, I seemed to recover a surge and urge to move, and even found the motivation to start going to the gym again. And well, we saw in the last post that melanotan-II / MC4R signalling in the brain dramatically increases GLUT4 on muscle. It all seems to fit together. ........atleast in theory.

Another correlation here is obese people have reduced secretion of GLP-1 in response to carb ingestion, and GLP-1 potently facilitates glucose disposal in muscle.