• Scientists discover body's natural alarm

    From ScienceDaily@1:317/3 to All on Mon Mar 28 22:30:40 2022
    Scientists discover body's natural alarm to battle blood loss

    Date:
    March 28, 2022
    Source:
    University of Virginia Health System
    Summary:
    Fresh insights into how the body responds to blood loss could lead
    to a new treatment for traumatic injuries.



    FULL STORY ========================================================================== University of Virginia School of Medicine scientists have discovered a
    cluster of cells in the brainstem that controls the body's response to
    severe blood loss, a finding which could benefit efforts to develop new treatments for traumatic injuries.


    ==========================================================================
    The discovery pinpoints a collection of neurons that drives a response
    that maintains blood pressure during blood loss. However, severe blood
    loss eventually causes cardiovascular collapse -- a condition termed "decompensated hemorrhage" marked by an abrupt and dangerous loss of
    blood pressure -- and the new results shed light on why that happens.

    "During blood loss, the brain coordinates a cardiovascular response that supports blood flow to critical organs, like the heart and brain,"said researcher George Souza, PhD, of UVA's Department of Pharmacology. "Our
    study shows that the cardiovascular response to blood loss depends on
    changes in the activity of a few hundred neurons in the brainstem."
    Under Pressure The new results, from UVA's Stephen Abbott, PhD, and collaborators, shed light on an important process the body uses to
    maintain its blood pressure. The neurons Abbott and his team describe -- properly known as "adrenergic C1 neurons" -- monitor blood pressure and
    swing into action during blood loss.

    When the neurons detect blood loss, they increase nerve activity that constricts blood vessels and maintains proper blood pressure.

    The scientists were able to determine this using advanced imaging and
    a technique called optogenetics that allows for the remote control of
    neurons using light. Their research revealed that the C1 neurons are hyperactive during blood loss, and this maintains blood pressure. But
    these neurons become inactive with severe blood loss, resulting in cardiovascular collapse.

    Decompensated hemorrhage is the prelude to hemorrhagic shock, in which
    the body begins to shut down. But the scientists found that re-activating
    the C1 neurons in lab rats restored both blood pressure and heart rate.

    "Our study indicates that reactivating the brain pathways controlling
    blood pressure during decompensated hemorrhage effectively reverses cardiovascular collapse. We think this indicates that neuromodulation
    of the pathways described by our study could be a beneficial adjunct
    therapy for low blood pressure following blood loss," said Abbott,
    of UVA's Department of Pharmacology.

    The scientists note that there may be several factors that contribute
    to the decline in the activity of the C1 neurons during the onset of decompensated hemorrhage. More research on that front is needed. But
    the team's findings identify important new directions for that future
    research.

    "These findings illuminate the importance of the brain-body interactions
    during blood loss and provide a new perspective for the underlying cause
    of cardiovascular collapse," Abbott said.

    The work was supported by the American Heart Association, grant
    19POST34430205, and the National Institutes of Health, grants HL148004,
    HL28785 and HL074011.


    ========================================================================== Story Source: Materials provided by
    University_of_Virginia_Health_System. Note: Content may be edited for
    style and length.


    ========================================================================== Journal Reference:
    1. George M.P.R. Souza, Ruth L. Stornetta, Daniel S. Stornetta,
    Patrice G.

    Guyenet, Stephen B.G. Abbott. Adrenergic C1 neurons monitor
    arterial blood pressure and determine the sympathetic response
    to hemorrhage. Cell Reports, 2022; 38 (10): 110480 DOI:
    10.1016/j.celrep.2022.110480 ==========================================================================

    Link to news story: https://www.sciencedaily.com/releases/2022/03/220328092053.htm

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