Saturday, August 25, 2012

Protons: SCD1 knockout mice

Let's peep inside an adipocyte belonging to a mouse which has had its stearoyl-CoA desaturase gene deleted.

It's busy making lipid, being an adipocyte. Two carbons, four carbons, six, eight, ten, twelve, fourteen and hey, there's the sixteen for palmitic acid. Now, how much glucose and insulin is there around? Ah, lots. Need to signal this with palmitoleate. In goes the double bond to prove it... Oops. No SCD1. Hmmmm. We now have a ton of palmitic acid and no chance to convert any of it to palmitoleic acid. Tricky.

Is the adipocyte going to become insulin resistant? Unless it runs on glucose and never uses any lipid this seems likely. Will the adipocyte stay small? It should do, it's insulin resistant, so won't store fat. Should it export saturated fat as FFAs? Yes. Should we have a slim but insulin resistant mouse? On chow it should become hyperinsulinaemic. Well, you might expect so.

But that's not what happens. The mice stay slim alright, but have excellent insulin sensitivity. Like really, really good insulin sensitivity. You can even feed them on toffee fudge cheesecake and they stay fairly slim and very insulin sensitive.

The SCD1 deleted mice also eat more despite being slimmer than WT mice when on chow, ie they are in CICO-denial:

"On average, the SCD1−/− mice consumed 25% more food than wild-type mice (4.1 g/day vs. 5.6 g/day; n = 9, P < 0.05). Nonetheless, they were leaner and accumulated less fat in their adipose tissue"

Huh. Bloody gym sneaks again. Even while they are asleep:

"The SCD1−/− mice exhibited consistently higher rates of oxygen consumption (had higher metabolic rates) than their wild-type littermates throughout the day and night (Fig. 3A). After adjusting for allometric scaling and gender, the effect of the knockout allele was highly significant (P = 0.00019, multiple ANOVA, Fig. 3B)."

These animals have a hugely increased metabolic rate. The brown adipose tissue "looks normal". That's not the answer.

They are also ketogenic during fasting (daytime is sleep time but they don't really go to the gym while they are asleep). Fasting BHB was 4.4mg/dl. For those watching their ketone meter at home, eat your heart out. They do this even when living on toffee fudge cheesecake.

OK. Utter basics:

What is the F:N ratio within the mitochondria of these mice? Is it:

a) <0.45
b) <0.45
c) <0.45
d) <0.45
e) <0.45
f) Huh????
g) >0.48 (trick answer, don't choose this one!)

The mice are insulin sensitive. They do not have undiluted palmitic acid oxidation going on in their mitochondria. This would produce a ton of superoxide and severe insulin resistance. We know that their mitochondrial F:N ratio must be low. Their metabolism is ketogenic. What fats produce ketones on a high carbohydrate diet? Those MCTs from coconuts and breast milk do. Where do you get C8 caprylic acid from if you are an SCD1 knockout mouse on a low fat diet?

From your peroxisiomes.

Mice with palmitic acid on tap and no ability to lower the F:N ratio by desaturation simply oxidise it in peroxisiomes, FADH2 free, to C8 which is ketogenic, has a low F:N ratio and they produce a lot of heat in the process.

In the words of the paper:

"Northern blot analysis also supports changes in fatty acid oxidation and lipid biosynthesis. Probes for acyl–CoA oxidase (ACO), very long chain acyl–CoA dehydrogenase (VLCAD), and carnitine palmitoyltransferase-1 (CPT-1) indicate increases in β-oxidation"

My emphasis. VLCAD is the main one in peroxisomes, as well as being present in mitochondria. The authors do not come up with any comprehensive explanation of what is going on. The F:N ratio delivers.

I think I mentioned some time ago the explanatory ability of the F:N ratio is awesome. It just goes on.

I was going to leave it there, back to work next week so blogging will diminish, but here is some idle rambling which followed on from this post.

Now here's the question. If some guy like me set out to maintain the lowest practical insulin level (which will minimise SCD1 activation) and bases his diet on the very longest chain, most fully saturated fat practical, would you expect me to activate my peroxisomes? Might the result be that I might stay slim and be cold tolerant?

When we moved in to our current house I unpacked the scales after they had spent nearly a year in a box provided by Pickfords. I was 63.8kg after a year of not checking anything, down by about a kilo from Glasgow. But I was getting a great deal of hill walking in Scotland and probably had more muscle. I forgot about the scales for another year but dug them out recently. Down to 62.8kgs. I eat a huge amount of palmitic acid. I generate enough superoxide to maintain the needed physiological insulin resistance to eat LCHF and I suspect I might have quite active peroxisomes.

I still run a dawn phenomemon FBG of around 5.5mmol/l, if I get up early enough to check it beforehand it's about 4.3mmol/l, once 3.9mmol/l. Random BG through the day vary from 3.3mmol/l after a half day of walking to and from the beach while the car was being MOTed to 6ishmmol/l post prandial if I had parsnip chips (yum) with my high fat beef burgers. Yes, I pour the cooking fat over the chips. A big carb load will get me above 7.0mmol/l easily but only for a couple of hours. I try not to do this too often.

Posting-wise I have no idea what time will allow next week but beta cell failure in SCD1 knockout ob/ob-ve mice tells us interesting things about cells which have minimal antioxidant defences and are deprived of palmitoleic and oleic acids.



Gretchen said...

Peter, I think you mean stearoyl–CoA desaturase, not steatoryl. I first thought you were discussing a new enzyme.

Peter said...



Puddleg said...

Surely it is more efficient, not less, (at least at low ambient temperatures) to generate heat metabolically, rather than using the same molecules to generate ATP, then using the ATP to shiver or fidget?
So perhaps the metabolic advantage is not always about inefficiency; some explanation more complex than mere waste may be needed. To also explain why 300Cal MAD might be better than 300Cal exercise or -300Cal starvation.

SS Biker said...


I have often wondered that - although more in the "why, if we're loaded with fat can't we just generate heat instead of being cold and miserable"....

Of course the answer is we can and if you were to ask Dr Kruse he'd prescribe CT.

I tell you what interests me, will Peter's children retain their innate Non-shivering thermogenesis capacity through not being exposed to excessive year-round dietary carbohydrate?

I have tried CT - spent 6 weeks doing it daily in the spring (when it was unseasonably cold) and it was miserable. Although during winter I very rarely put the heating on and consider myself fairly "cold tolerant". Since going pretty much zero carb though I frequently notice the tell-tale radiant heat in my upper back and general sensation of feeling "hot to the touch" all over. Roll on winter ;-)

Unknown said...

Why is this O numnos? Most likely you're free T3 is low......get it checked and replete it and watch how easy CTing becomes. You want it to be in the top ten % of the reference range for the lab. Modern life is what limits free T3 production in the brain because of the lowered melatonin in the pineal, When T3 is low your LDL rises and you cant make hormones. This is why so many who go paleo get a flu when they change and they don't realize why. It is because of pregnenolone steal syndrome. I wrote about it over a year ago in a blog post called the Hormone 101 blog post

Eva said...

Jack, I suspect part of the lowcarb 'flu' is often caused by wheat withdrawal. Wheat acts like an opiate and withdrawal after long term exposure causes druglike withdrawal symptoms in many. I didn't know about that until I started reading more about Wheat from the celiac community. According to many celiacs, all wheat eaters experience either some withdrawal or a lot of withdrawal when giving it up. Wheat is amazingly creepy in all the many problems it can cause! I wonder how many probs are centered just around wheat.

Kitavans eat a lot of carb and they seem rather healthy! It may not be the ideal diet in the entire universe but apparently humans can do rather decently on a ton of carb in some situations. Could it be lack of wheat, excitotoxins, etc that makes some of the diff? If excitotoxins damage the nervous system, and nervous system is responsible for telling fat cells when to stop making fat, you could see a potential prob brewing there! Might be why some people can't heal on just low carb. MSG, aspartame, rancid grain oils, high fructose corn syrup, etc. There are a lot of potential suspects in this crime!

SS Biker said...

@Dr K

It wasn't the CT per se but the post CT warm-up in 50°F air temps that was miserable. For one week the weather improved (70°F) and it was actually very pleasant.

karl said...

I started a page looking at all the types of fats 3 years ago after thinking that the "fats are bad" mantra might apply only to a subset of fats. ( I had not realized how many bad papers were about at the time and I don't know if the ones I have linked here are of quality )
- but I was looking for fats effects on oxLDL ( which may well be at least in part due to BG ) and found that the subject would turn into a full time job so the page sits unfinished. ( edits quite welcome )

My hunch is that in normal non e4/e4 people with out hyper-cholesterolerima LDL is harmless unless it gets turned into oxLDL.

Now reading your posts has me interested again - The only thing I have confidence in so far is the the medical community 'experts' don't know much yet..

RE Palmitic acid - This article bothers me -

The uptake of oxLDL is central to atherosclerosis - LOX-1 is blocked by statins AND I think that is the real way they do some good - ( rather than lowering LDL) .

Edward Edmonds said...

I was wondering when you were going to bring the peroxisomes in.

I'm feeling unusually satisfied.

Edward Edmonds said...

At < 50g CHO I was burning up. I was eating/drinking a LOT of butter. Which seems suitable for dancing naked on an ice cap.

Nigel Kinbrum said...

Peter, you wrote:-

"These animals have a hugely increased metabolic rate. The brown adipose tissue "looks normal". That's not the answer."

In what way does a rodent's BAT "look abnormal" when it up-regulates its heat production?

Cheers, Nige.

SS Biker said...


One of Peter's previous posts looks at the wisdom of drawing dietary conclusions from treating isolated cells with particular fatty acids (Palmitic again).

Don't know if that helps allay any fears though.

Puddleg said...

@ Karl,

This might help:

I have long had a hunch about air conditioning and obesity.
If peroxisomal oxidation is more protective against adposity than ATP generation/expense, or is synergistic, calories not being calories, this would explain why Colorado is the least obese state of the great US of A.
Further, there is some loose talk about lab animals being fatter today, even those on the same rations.
"Rats, mice and primates (four types were analyzed in this study) in laboratories are fed a highly controlled, known diet that has remained relatively constant over time. Why are these animals getting fatter?

Perhaps for some reason they're choosing to eat more of what they are offered or are somehow changing how they metabolize it, he said.

Allison pointed out at least three potential contributions to this and the other observations: endocrine disrupting chemicals, pathogens such as a virus, and/or changes in temperature where the animals are kept."

I might also add, improved hygiene practices.

Eva said...

"Rats, mice and primates (four types were analyzed in this study) in laboratories are fed a highly controlled, known diet that has remained relatively constant over time. Why are these animals getting fatter?"

This is interesting, but are you SOOO sure their diet hasn't changed? Even if it's still corn and wheat and whatever, corn is now GMO corn, wheat is now frankenwheat with double chromosomes, novel proteins, etc. Most food is GMO with new built in lectins and pesticides made by the plant itself. It is grown in more depleted soil with more chemicals. This same crap is in the rat chow. The water is often full of fluoride and other chemicals. Animal products not only are eating that same thing before they die but also are also treated with chemicals, antibiotics, and hormones and then the meat is dipped in more chemicals to preserve it before packaging. Are you so so sure that the rat chow is EXACTLY the same as before? None of our food is the same, from rennet in cheese (now made by GMO bacteria) to soy sauce (usually no longer fermented) to milk to yeast, it's all different!!

Not so surprising if even the rats are getting fatter. Either that or the rats are lazier now and they aren't getting enough exercise. Blame it on TV and the internet! ;-P

Another potential issue is epigenetics and or genetic drift. COuld be damage via unhealthy chow and other unhealthy exposures has accumulated through the generations. Or also, a few more thousands of generations are a few more thou of generations away from being wild. There is always evolution. What is the current survival of the fittest for lab rats? Food is usually plentiful so animals that give birth to the most young have the advantage. Other potential advantages, rats that get along with others, handle confinement better, bite less, survive better on crappy rat chow, etc are likely bred more. Maybe there is survival advantage for lab rats that are fat and lazy and obedient, so now you have more of them. Every breed of every animal that humans breed is continually changing, even if we claim vehemently that we are keeping them the same. Even many dog breeds which are supposed to be bred to never changing breed standards have morphed quite a bit in just 20 years.

Stipetic said...

Just wanted to drop word that this series is fascinating. Thanks, Peter.

Puddleg said...

Eva, yes it occurred to me that this can hardly be proven.
Lab rats are culled based on selective criteria.
Those that don't "play the game" and the obviously unhealthy young are first to go.
This is selective breeding.
Besides, he asks "are they eating more?".
So they're not even being fed the same amounts?
Chimps age at a human rate. Chimp populations, given the difficulty of replacement, are probably older on average.
Epigenetics, GMOs, familial decline, uncanny animal traditions handed down over generations.
Exposure to food advertising on laboratory radios and posters....

Nonetheless some interesting titbits in the paper; the obesity-promoting adenovirus is fascinating.

Puddleg said...

A recent pro-fat story that nearly slipped under the radar:

Dietary Fat and Heart Failure: Moving From Lipotoxicity to Lipoprotection
William C. Stanley, Erinne R. Dabkowski, Rogerio F. Ribeiro Jr, Kelly A. O'Connell

There is growing evidence suggesting that dietary fat intake affects the development and progression of heart failure. Studies in rodents show that in the absence of obesity, replacing refined carbohydrate with fat can attenuate or prevent ventricular expansion and contractile dysfunction in response to hypertension, infarction, or genetic cardiomyopathy. Relatively low intake of n-3 polyunsaturated fatty acids from marine sources alters cardiac membrane phospholipid fatty acid composition, decreases the onset of new heart failure, and slows the progression of established heart failure. This effect is associated with decreased inflammation and improved resistance to mitochondrial permeability transition. High intake of saturated, monounsaturated, or n-6 polyunsaturated fatty acids has also shown beneficial effects in rodent studies. The underlying mechanisms are complex, and a more thorough understanding is needed of the effects on cardiac phospholipids, lipid metabolites, and metabolic flux in the normal and failing heart. In summary, manipulation of dietary fat intake shows promise in the prevention and treatment of heart failure. Clinical studies generally support high intake of n-3 polyunsaturated fatty acids from marine sources to prevent and treat heart failure. Additional clinical and animals studies are needed to determine the optimal diet in terms of saturated, monounsaturated, and n-6 polyunsaturated fatty acids intake for this vulnerable patient population.

Thanks to Hannah Sutter, Author of Big Fat Lies

Puddleg said...

Did anyone notice this line from the abstract above:

This effect is associated with decreased inflammation and *improved resistance to mitochondrial permeability transition*.

Edward Edmonds said...

Re: Temperature

My temperature consistently ran in the high 98's and low 99's both under the arm and orally. I've seen that people blame the cold on low thyroid. I have a tendency to think based off some of the symptoms and time frames people describe that it actually is reactive hypoglycemia/hypoglycemia. I haven't read all the dietary contexts in which it happens but it seemed to be those who were somewhat in between VLC and LC. So somewhere in between lets say 50-75g as an example. I think there is a narrow window where if you don't keep your CHO consistent that your body will flip-flop very easily with how much CHO you are eating. If you are eating VLC and you are in a situation where you are constantly using ketones I think that is probably a good stable situation keeping yourself in a glucose deficit deep enough to where you always relying on ketones to feed the brain. But I think if you are on the edge of VLC where you are using ketones but you ingest few grams extra CHO than what is normal for you it pushes you over that edge and you start involving a little extra insulin to keep blood sugar regulated. Once you burn off that tiny bit of glucose I think the body panics and you'll get a little hypoglycemia until the body can ramp back up ketone production. So every now and then that flip flop is probably no big deal, but I read these descriptions and I think people panic, eat some CHO, and enter into a vicious cycle where they are definitely LC but they are eating just enough CHO to where it fluxes the ketone concentration out of a "sweet spot". This constant back and forth of using ketones and then not probably could induce some thyroid issues because when you are eating just enough CHO to keep ketones high and then ingest a little extra CHO to shut the usage of ketones down a bit, that transition is probably similar to what happens when you first enter a starvation state. So your glucose drops your body panics thinks there is a glucose shortage, slows the metabolism a bit, ramps up ketone production and then temperature comes back to normal. I think if this happens chronically I could see how you'd start messing with the thyroid. I don't think it is any type of permanent damage I just think what these people are experiencing is chronic symptoms but I think it is completely normal physiology under the circumstances.

I think this can be made worse if you're restricting salt and you are hypocaloric or fluid intake is on the high side. The solution I think is to either remain slightly hypercaloric or to keep the CHO level very consistent and strict. Even when sedentary, I can put down 4000 calories and not gain an ounce, as long as CHO is 30-40g. When I increase my CHO higher I have to decrease total calories or risk gaining a little weight (silly insulin), even if my activity level is high, I have run a temperature a few points (0.x) lower than what is normal for me, but this totally seems to be related to back and forth fluxes of CHO and ketone usage rather than actually needing them for some physiological reason. I think that coconut oil might make this worse in some scenarios.

We do loose water weight when LC, but we also are making more water as a result of burning fat. There are some desert mammals that rely on this to stay hydrated. I think if you are active it probably is wise to replace water lost but I think if you are sedentary that you should drink to thirst so that you don't dilute yourself and activate RAAS.

I think coconut oil generated heat is metabolically generated heat in the true sense (ATP). Peroxisome generated heat is the result of a catabolic reaction when VLCFAs and LCFAs are beta-oxidized i.e. free heat (that's the compulsory benefit of eating the right fuel :).

Dr Bob said...

What is the F:N ratio?, I do not understand.

Peter said...

Dr Bob,

The concept is hammered out in the Protons series. Scroll down the labels list until you get to series of posts starting with "Protons" then dig in from there.

Edward, I'm chronically hypothermic on waking. I'm also hyperactive once awake. I've been named Tigger by at least one practice secretary, probably with good reason! I certainly doubt that I am functionally hypothyroid.

I do some of the things you suggest, certainly I'm more hypercaloric than I was early in LC eating... But also somewhat deeper in to ketosis.


Jacob said...

Amazing blog here Peter!

I am very interested in C8. Babies are in ketosis during breastfeeding, yet they eat quite a bit of milk-sugars from milk. Do you think C8 has a part to play here?

I have been thinking about potentially using a mix of C8 and skim milk, as the majority of my calories, to allow insulin function whilst also making ketones.

I want to be like the SCD1 KO mice.

Would you still say that burning SFA's is preferable?

Thanks. Great blog.

Peter said...

Jacob, my approach is to resist insulin. Minimise ILGF1 signalling, minimise mTOR signalling. Palmitate is my preferred fat...