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  1. #1
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    Default Leptin, leptin resistance vs. IR, how leptin-resistance actually works, l-carnitine?

    Update post 10: after 6 months of L-carnitine supplementation, leptin blood levels decreased from abnormally high to within normal range, above median. Not a controlled experiment.

    The annual Cushings/IR bloodwork came back recently (I've always considered a formal diagnosis of one or the other to be a when, not if, proposition with my very easy keeper ISH and have treated him more or less like he's IR.) He does not have Cushings, he is not insulin-resistant, but he is apparently leptin-resistant. (High leptin concentration was the only result out of normal range.) Cue Googling to learn more about a hormone I'd only seen mentioned in a cursory fashion in a psychopharmacology textbook featuring that "fat mouse, thin mouse" photo.

    I read Dr. Kellon's "Considerations for the IR horse" where she states that IR horses are also leptin-resistant. From that statement and the fact that mine is leptin-resistant but not IR it seems like this could be a rectangles and squares proposition- "IR horses are leptin-resistant but not all leptin-resistant horses are IR." It seems from my reading that the two resistances co-occur because insulin increases leptin concentration. Am I right in thinking that this may be a correlation or it may be causatory but it definitely doesn't go the other way around- in other words, does leptin resistance without current insulin resistance increase the odds of later insulin resistance?

    Beyond an increase of exercise, which is not very possible at the moment because the horse still on the layup plan after diagnosis of sesamoiditis and a tweak of an old suspensory injury, the vet recommended supplementation with l-carnitine. I am fairly skeptical but a $10/month experiment with something that appears to promote bone health and remodeling is not going to hurt a horse with a diagnosed degenerative bone condition. However, the one piece of equine research I found on the specific subject of l-carnitine and leptin (actually just the abstract- http://www.ncbi.nlm.nih.gov/pubmed/19320933) seems from the abstract to indicate that l-carnitine actually boosts blood concentration of leptin. A 2004 study on swine by Woolworth et. al.- again I can only get at the abstract- had similar results. I don't think I understand how this could be helpful- am I correct that increasing blood leptin levels above an already abnormally high concentration would promote, rather than improve, leptin resistance? I see l-carnitine being touted as a potential "weight loss drug" (and the last time I spoke to a physician, albeit not an endocrinologist, about this I was given to understand that that advertisement isn't entirely spurious) so I assume there is something I am missing about how leptin resistance works and/or about how l-carnitine works with leptin. Can someone please help fill me in?

    Other than the articles mentioned above and Joshua Cartmill's 2004 dissertation from LSU I didn't find any other scholarly research on leptin as it specifically relates to the horse. If any of you happen to know of any additional research I should add to my reading pile, would you please sing out?

    Thanks in advance for any assistance. I did search through the forums first but it appears that discussion of leptin only comes up in conjunction with, and secondary to, IR. Since my guy is apparently not IR (yet...) I'm more interested for now in leptin-resistance on its own.
    Last edited by Renn/aissance; Jul. 31, 2013 at 03:50 PM.
    "I'm not always sarcastic. Sometimes I'm asleep."
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  2. #2
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    Default

    Never mind. Need caffeine!
    Click here before you buy.



  3. #3
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    Hi DW, this question was brought up in our nutrition course in the discussion forum.

    To the OP, the answer was disappointing, apparently if anything could help LR, then it would be immensely popular with humans, so that ended the discussion .

    As for l-carnitine, it does not harm, I have one horse on it.



  4. #4
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    I barely have time to keep up with the lectures, much less the discussion forums! I'm sure with 25,000+ people taking the course the discussions are . . . in depth. I'm staying out of it.
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  5. #5
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    I am enrolled in that course but am well behind. Holes in your kitchen ceiling have that effect. I will have to take a deep breath and dive into the discussion board. For the reason DW mentioned, I'm a bit afraid to do that.
    "I'm not always sarcastic. Sometimes I'm asleep."
    - Harry Dresden

    Horse Isle 2: Legend of the Esrohs LifeCycle Breeding and competition MMORPG



  6. #6
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    Quote Originally Posted by Renn/aissance View Post

    I read Dr. Kellon's "Considerations for the IR horse" where she states that IR horses are also leptin-resistant.
    Both my IR ponies had very low leptin, so that blows that theory. AAKG made no difference to insulin levels or laminitis on the pony I tried it on.
    The studies showing a correlation between leptin and insulin had insufficient numbers of horses to make broad statements.
    No suggestion about causation has been made by any reputable researcher.



  7. #7
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    DW & Rennaissance, exactly, I've gone quiet on COTH here, because I can barely keep up too. But loving it however.
    The discussion forum does go more in depth on certain issues, but quite some stuff I had already learned from COTH anyway. So let's keep are discussions going here, we have so many knowledgeable posters on here .



  8. #8
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    Plus, here I've already figured out who is worth listening to and who is not. If I have to go somewhere else I'll have to start all over again!
    "I'm not always sarcastic. Sometimes I'm asleep."
    - Harry Dresden

    Horse Isle 2: Legend of the Esrohs LifeCycle Breeding and competition MMORPG



  9. #9
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    Very true! I've certainly come to value the info provided by some of our posters here.

    Just in case you were to want to go onto the forums without losing too much time, they have a subform where the tutors give answers instead of just the student members, so at least those have more reliable information.



  10. #10
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    I have a gelding who is slightly IR and originally also had high leptin levels. Through diet and him losing some weight both levels have come back down into "normal" ranges. Also, I'd like to note he was never overweight but on the slightly higher side of normal weight wise.



  11. #11
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    I greatly hesitated to post this because one data point isn't a study and this wasn't really a controlled endeavor (hay supplier changed, turnout time increased...) but I've had enough PM's asking for follow-up that I'm going to go ahead and talk about it. Tip's leptin levels in early February were very high. The vet suggested L-Carnitine, 1500mg 2x/week, and he has been on that regimen for 6 months. His leptin levels were tested again in early July; they are now just slightly above normal. I don't have numerical values offhand until I see the print-out myself.
    "I'm not always sarcastic. Sometimes I'm asleep."
    - Harry Dresden

    Horse Isle 2: Legend of the Esrohs LifeCycle Breeding and competition MMORPG



  12. #12
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    I know this relates to HUMANS but there is a lot of info about leptin, insulin, etc in Fat Chance by Robert Lustig
    I wasn't always a Smurf
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  13. #13
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    I'd put Lustig in the category of people who are out there publishing books for the mass-market instead of scientific papers to further our base of knowledge. Nothing wrong with writing a book and making a buck, but not everyone with a degree is a real "expert" (I include myself, no question) or dispassionate and without an agenda (more the case with Lustig--he has good credentials) and there are a whole lot of ACTUAL experts who violently disagree with his work. Just sayin'. My opinion is in the center, as it almost always is.
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  14. #14
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    Leptin & insulin are both adiposy signals, with leptin being the primary one. Leptin levels should reflect fat stores, telling the body if it needs more or less and adjusting appetite & metabolic rate (long term adjustments) accordingly.

    being insulin resistant and/or leptin resistant makes one incredibly efficient in terms of metabolism: body will keep trying to get & store as much as it can. If one is resistant, the signals levels increase even if stores are adequate, body keeps ignoring...and storing...& wanting more. IR & LR do tend to go together & w/ EMS, but technically one could be IR without LR, although that seems unlikely. The genetic predisposition towards thriftiness would create tendency to resist both. The good news was your ancestors lived through the famine, the bad news is that today you are in trouble.

    JAVMA, 2010: Equine Metabolic Syndrome, Frank et al state: "Chromium, magnesium, cinnamon, and chasteberry (Vitex agnus-castus) are commonly recommended for the management of EMS. It was the consensus of the panel that there is insufficient scientific evidence to support the use of these supplements at this time and that results of controlled studies should be examined before these products are recommended."



  15. #15
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    Quote Originally Posted by deltawave View Post
    I'd put Lustig in the category of people who are out there publishing books for the mass-market instead of scientific papers to further our base of knowledge. Nothing wrong with writing a book and making a buck, but not everyone with a degree is a real "expert" (I include myself, no question) or dispassionate and without an agenda (more the case with Lustig--he has good credentials) and there are a whole lot of ACTUAL experts who violently disagree with his work. Just sayin'. My opinion is in the center, as it almost always is.
    ++thumbs up



  16. #16
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    Quote Originally Posted by deltawave View Post
    I'd put Lustig in the category of people who are out there publishing books for the mass-market instead of scientific papers to further our base of knowledge. Nothing wrong with writing a book and making a buck, but not everyone with a degree is a real "expert" (I include myself, no question) or dispassionate and without an agenda (more the case with Lustig--he has good credentials) and there are a whole lot of ACTUAL experts who violently disagree with his work. Just sayin'. My opinion is in the center, as it almost always is.
    Lustig also provides good references.

    People are not all the same. Some people metabolize sugar better than others. Some horses metabolize sugars better than others do. Some can eat all sorts of carbs and never develop a problem. Lustig's scenario doesn't apply to all people. but it DOES apply to some.
    I wasn't always a Smurf
    Penmerryl's Sophie RIDSH
    "I ain't as good as I once was but I'm as good once as I ever was"
    The ignore list is my friend. It takes 2 to argue.



  17. #17
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    Every scenario applies to SOMETHING, some of the time. That's not how books are sold, however.

    His credentials are excellent. References are solid. Conclusions drawn, however, have been widely critiqued by his colleagues.

    MY favorite mass-market book that tells us all about how we're screwing up and going to die any minute is "The Cure for Everything" by Caulfield. Wonderful and badly needed in the "here's a book on why everything you're doing is wrong" genre.
    Click here before you buy.


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