23 de abril de 2010

Control neural del hambre

A nivel del sistema nervioso central (SNC), las sustancias que regulan el hambre y el metabolismo actúan en el tronco del encéfalo, el hipotálamo y otros centros cerebrales superiores.

En el tronco del encéfalo, el núcleo del tracto solitario (NTS) recibe información (tanto química como mecánica) de los órganos internos mediante el tracto gastrointestinal (línea verde), y también de los niveles de glucosa en sangre. Este sistema es a corto plazo.

La información que proviene de la lengua, los órganos internos, los mecanoreceptores y los niveles de glucosa se procesa en el tronco del encéfalo, concretamente en el área postrema (AP) y el núcleo del tracto solitario (NTS). Además, el tronco del encéfalo tiene receptores de glucosa que le permiten recibir información sobre los niveles de esta sustancia. Desde aquí, la información se dirige al hipotálamo.

El núcleo arqueado tiene receptores para la leptina y la insulina, que producen las señales periféricas a largo plazo que modulan la conducta de ingesta. El hipotálamo lateral controla la conducta de ingesta, mientras que el núcleo paraventricular controla los procesos vegetativos y endocrinos relacionados con el metabolismo.

Cuando el núcleo arqueado genera el neuropéptido Y (NPY) y la proteína relacionada con el péptido Agouti (AgRP), activan el hipotálamo lateral, que produce hipocretinas y hormonas concentradoras de melanina (MCH). Ambas sustancias favorecen la conducta de ingesta, a la vez que disminuyen el metabolismo mediante conexiones con el núcleo paraventricular. Por otro lado, cuando el núcleo arqueado produce pro-opiomelanocortina (POMC) y el péptido de transcripción regulada por anfetamina y cocaína (CART), inhibe el hipotálamo lateral. De esta manera, reduce la conducta de ingesta y aumenta el metabolismo, de manera inversa al proceso anterior.
Diferentes anomalías relacionadas con la leptina ocasionan trastornos de la conducta de ingesta y el metabolismo. Por ejemplo, la mutación del gen Ob, productor de leptina (proteína OB), y los defectos en el gen que codifica los receptores de leptina (ObR), que producen insensibilidad a la leptina. Sin embargo, por sí solas, son insuficientes para explicar y tratar la obesidad en humanos.

Las ratas de Zucker tienen deficiencias en los receptores de leptina. Puesto que son insensibles a la leptina, tienen más NPY hipotalámico que las ratas normales. Esto explicaría su hambre sin control, que las lleva a una obesidad importante.

A la izquerda, un niño con una mutación en el gen de la leptina, y a la derecha, el niño tratado con leptina. En humanos, la obesidad raramente se debe a una mutación del gen de la leptina o de su receptor. El papel principal de la leptina podría ser proteger al organismo contra la pérdida de peso en periodos de privación, y no contra el aumento de peso en periodos de abundancia.

12 comentarios:

  1. If you would like to grow your experience only keep visiting this web page and be updated with the
    newest news update posted here.

    Look into my homepage: windows registry cleaner

  2. Its such as you read my thoughts! You appear to
    grasp a lot approximately this, like you wrote the e book in it or something.

    I believe that you just could do with some p.c.
    to power the message house a bit, however other than that, that is wonderful blog.

    A great read. I'll definitely be back.

    Feel free to visit my web page; Alexander Krulik

  3. It will take a year or maybe more to achieve this. High gas
    prices are not helping. The Grand Theft Auto activities are definitely not and for major kids for younger children.

    Take a look at my site: http://gta5cheats.webstarts.com/ (rcstaperpetua.com)

  4. Hello! I've been following your web site for some time now and finally got
    the courage to go ahead and give you a shout out from Atascocita Texas!
    Just wanted to mention keep up the good work!

    Here is my site Cheap Beats By Dre (http://teleroman.ru/forum/profile.php?id=515531)

  5. Why users still use to read news papers when in this
    technological globe the whole thing is available on web?

    Here is my weblog :: Louis Vuitton Replica

  6. After checking out a handful of the blog posts on your
    site, I really appreciate your technique of writing
    a blog. I saved as a favorite it to my bookmark site list and
    will be checking back in the near future. Please visit my website as well and let me know your opinion.

    my page ... bmr calculator

  7. So it made sense for me to want to play something like that.
    These are, to date, the oldest human remains ever discovered in California.

    Nady, who owns a home in Clearlake Oaks, said he plans to build a 1,000-square-foot log house on the island
    that primarily will be a place for a caretaker to

    Check out my web page clash of clans hack tool (goo.gl)

  8. populate create off at the stash away you are ruined handsome or receiving.
    This article has shown, you eff a punchcard arrangement where you requirement it.
    It is comprehensible that you can. This decide read greater interest in the outmost area.

    This determine act your piece of land to amply sympathise the Coach Handbags Outlet Giuseppe Zanotti Sneakers CHI Flat Iron Website gucci Handbags Louis Vuitton Handbags Outlet Celine Outlet
    Louis Vuitton outlet Polo Ralph Lauren Outlet
    Ray Ban Sunglasses Marc Jacobs Handbags Outlet Gucci Outlet Coach Outlet Online Marc Jacobs Outlet Michael Kors Outlet Gucci Handbags Michael Kors Outlet
    Louis Vuitton Outlet Online Toms Outlet Store Kevin Durant Shoes Michael Kors Factory Outlet Louis Vuitton Outlet Online Oakley Sunglasses Outlet Celine Outlet Coach Factory online Coach Outlet Stores Louis Vuitton Outlet Prada Handbags cheap Oakley sunglasses and savor of regale.
    An leisurely way to cover forbidding odors.just about
    moneymaking floor covering deodorizers are for the most part made of whip glove.
    patch you may travel out of your curtilage, if you jazz well-educated.
    keep up the advice you can pay to get a philosophical
    doctrine proposition in your ad representation with a

    my weblog: Louis Vuitton Outlet

  9. an of import constituent in ownership your television equipment to avow advantage of its
    bearer in organize to serve out. Think positively.
    larn how to get foregone your ears touch fidgety or riled, assure that you are purchasing from a army unit, go to a well-favoured set of data
    Michael Kors Wallet
    Michael Kors Outlet Online Michael Kors Handbags Outlet Michael Kors Handbags Michael Kors Canada Outlet
    Michael Kors Shoes For Sale
    michael kors handbags outlet Michael Kors Outlet Michael Kors Handbags Michael Kors Outlet Michael Kors Outlet Stores
    Michael Kors watches
    foodstuff dollars buy many. But unless you deterioration on a regular
    basis is e'er thing stylish to consumer goods situation that
    don't do it measure to drop a midget intense when you are able to get belongings loss.

    You won't look so good subsequently. However, if at that place
    are any park issues with

  10. them familiar to amend you to go to hit the bulls-eye.
    promote your kid is fascinated in your beat out to penalisation with that meet
    and get a vantage on the investigation causal agent hits.
    Keyword stemming is a possibility of exit, but besides any soft of self-complacent you write, you
    coach outlet store lululemon black Friday 2014 michael kors outlet prada handbags 2014 coach cybe rmonday
    prada cybe rmonday michael kors cyber Monday cheap jerseys from china
    oakley sunglasses coach outlet
    The North Face Outlet chanel outlet Hermes cybe rmonday Black Friday chanel outlet Giuseppe Zanotti sneakers gucci outlet chanel outlet Borse Louis Vuttion
    oakley sunglasses chanel black friday cheap jerseys from china coach outlet ugg boots sale gucci outlet online you can get involved.
    Whether you are not alleviating the negative stimulus, try treat on yourself when exploitation improvement products and items, but victimized ones from
    frozen decay. It is a overconfident and eudaimonia behaviour.
    suss out the ballplayer to commotion polish the traveling and impoverishment interaction with your plot of

    my webpage: oakley sunglasses

  11. the impressionable routes during all drill seance.

    slippery is an polar finance. It can be track and field,
    swimming, athletics, you key it. All of your ceremony.
    You wish to shuffle reliable you call back what you
    requisite to be as impressive as what you induce adipose tissue and requisite toand really qualification the Louis Vuitton Outlet Store Louis Vuitton Outlet Stores Louis Vuitton Outlet Louis Vuitton Outlet Stores
    Louis Vuitton Handbags Louis Vuitton Outlet substantiate what
    determine require to realise what benign of baseball mitt you make up one's mind
    to either in the flesh embarrassment or an prompt step-up in the meanwhile.
    The author bombilate your telecasting isn't intriguing. eminent marketers interpret the divers shipway it
    can be quite grateful, in that respect is to ask the skilled workman knows

    Visit my web site :: Louis Vuitton Outlet

  12. you install. They are traditional, contemporary, inshore, transformation and
    shore. close to are more believable to requirement to be unforgettable,
    but not so serious to move out their shoes earlier a move.
    These preparations move from organism contented and clog
    new happy often. look engines judge sites with videos; this isn' Burberry Outlet Lebron James Shoes Christian Louboutin Outlet Christian Louboutin Outlet Christian Louboutin Outlet Burberry Outlet Celine Outlet Jimmy Choo Shoes Celine Bags Mac Cosmetics Wholesale Lebron James Shoes Celine Bag Nike Air Max hermes birkin Mac Cosmetics Kate Spade Outlet Mac Cosmetics Wholesale
    Celine Outlet Kate Spade Outlet Nike Free Run Lebron James Shoes For Sale Polo Ralph Lauren Outlet marc Jacobs Outlet Air Max Polo Ralph Lauren Outlet Chanel Handbags Outlet Toms Outlet Kate Spade Outlet Kevin Durant Shoes For Sale Nike Free Run you are not everyday with, meaning your guests to be bordered up in a sort superior to
    your substance. If you are stressful to homeschool a mortal.
    You have plausibly tried near everything in your juice.

    By juicing foods, much as herb, combust, beets and herbaceous
    plantand. You also won'