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Effects of hypothermia on cerebral autoregulatory vascular responses in two rodent models of traumatic brain injury.

Abstract

Traumatic brain injury (TBI) can trigger disturbances of cerebral pressure autoregulation that can translate into the generation of secondary insults and increased morbidity/mortality. Few therapies have been developed to attenuate the damaging consequences of disturbed autoregulatory control, although some suggest that hypothermia may exert such protection. Here we reexamine this issue of traumatically induced autoregulatory disturbances and their modulation by hypothermic intervention, examining these phenomena in two different models of TBI. Adult rats were subjected to either impact acceleration injury (IAI) or lateral fluid percussion injury (LFPI) followed by the insertion of cranial windows to assess the pial arteriolar cerebral autoregulatory vascular response to the post-traumatic induction of sequential reductions of arterial blood pressure. The potential for continued pial vasodilation in response to declining blood pressure was directly measured post-injury and compared with that in injured groups subjected to 33° C of hypothermia of 1-2 h duration initiated 1 h post-injury. We observed that the TBI resulted in either impaired or abolished cerebral vascular dilation in response to the sequential declines in blood pressure. Following IAI there was a 50% reduction in the vasculature's ability to dilate in response to the induced hypotension. In contrast, following LFPI, the vascular response to hypotension was abolished both ipsilateral and contralateral to the LFPI. In animals sustaining IAI, the use of 1 h post-traumatic hypothermia preserved vascular dilation in response to declines in blood pressure in contrast to the LFPI in which the use of the same strategy afforded no improvement. However, with LFPI, the use of 2 h of hypothermia provided partial vascular protection. These results clearly illustrate that TBI can alter the cerebral autoregulatory vascular response to sequentially induced hypotensive insult, whereas the use of post-traumatic hypothermia provides benefit. Collectively, these studies also demonstrate that different animal models of TBI can evoke different biological responses to injury.

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  • Authors+Show Affiliations

    ,

    Department of Anatomy and Neurobiology, Virginia Commonwealth University Medical Center, Richmond, Virginia 23298, USA.

    ,

    Source

    Journal of neurotrauma 29:7 2012 May 01 pg 1491-8

    MeSH

    Animals
    Brain Injuries
    Cerebrovascular Circulation
    Disease Models, Animal
    Homeostasis
    Hypothermia, Induced
    Male
    Rats
    Rats, Sprague-Dawley

    Pub Type(s)

    Comparative Study
    Journal Article
    Research Support, N.I.H., Extramural

    Language

    eng

    PubMed ID

    22364620

    Citation

    Fujita, Motoki, et al. "Effects of Hypothermia On Cerebral Autoregulatory Vascular Responses in Two Rodent Models of Traumatic Brain Injury." Journal of Neurotrauma, vol. 29, no. 7, 2012, pp. 1491-8.
    Fujita M, Wei EP, Povlishock JT. Effects of hypothermia on cerebral autoregulatory vascular responses in two rodent models of traumatic brain injury. J Neurotrauma. 2012;29(7):1491-8.
    Fujita, M., Wei, E. P., & Povlishock, J. T. (2012). Effects of hypothermia on cerebral autoregulatory vascular responses in two rodent models of traumatic brain injury. Journal of Neurotrauma, 29(7), pp. 1491-8. doi:10.1089/neu.2011.2278.
    Fujita M, Wei EP, Povlishock JT. Effects of Hypothermia On Cerebral Autoregulatory Vascular Responses in Two Rodent Models of Traumatic Brain Injury. J Neurotrauma. 2012 May 1;29(7):1491-8. PubMed PMID: 22364620.
    * Article titles in AMA citation format should be in sentence-case
    TY - JOUR T1 - Effects of hypothermia on cerebral autoregulatory vascular responses in two rodent models of traumatic brain injury. AU - Fujita,Motoki, AU - Wei,Enoch P, AU - Povlishock,John T, Y1 - 2012/04/16/ PY - 2012/2/28/entrez PY - 2012/3/1/pubmed PY - 2013/2/6/medline SP - 1491 EP - 8 JF - Journal of neurotrauma JO - J. Neurotrauma VL - 29 IS - 7 N2 - Traumatic brain injury (TBI) can trigger disturbances of cerebral pressure autoregulation that can translate into the generation of secondary insults and increased morbidity/mortality. Few therapies have been developed to attenuate the damaging consequences of disturbed autoregulatory control, although some suggest that hypothermia may exert such protection. Here we reexamine this issue of traumatically induced autoregulatory disturbances and their modulation by hypothermic intervention, examining these phenomena in two different models of TBI. Adult rats were subjected to either impact acceleration injury (IAI) or lateral fluid percussion injury (LFPI) followed by the insertion of cranial windows to assess the pial arteriolar cerebral autoregulatory vascular response to the post-traumatic induction of sequential reductions of arterial blood pressure. The potential for continued pial vasodilation in response to declining blood pressure was directly measured post-injury and compared with that in injured groups subjected to 33° C of hypothermia of 1-2 h duration initiated 1 h post-injury. We observed that the TBI resulted in either impaired or abolished cerebral vascular dilation in response to the sequential declines in blood pressure. Following IAI there was a 50% reduction in the vasculature's ability to dilate in response to the induced hypotension. In contrast, following LFPI, the vascular response to hypotension was abolished both ipsilateral and contralateral to the LFPI. In animals sustaining IAI, the use of 1 h post-traumatic hypothermia preserved vascular dilation in response to declines in blood pressure in contrast to the LFPI in which the use of the same strategy afforded no improvement. However, with LFPI, the use of 2 h of hypothermia provided partial vascular protection. These results clearly illustrate that TBI can alter the cerebral autoregulatory vascular response to sequentially induced hypotensive insult, whereas the use of post-traumatic hypothermia provides benefit. Collectively, these studies also demonstrate that different animal models of TBI can evoke different biological responses to injury. SN - 1557-9042 UR - https://www.unboundmedicine.com/medline/citation/22364620/abstract/Effects_of_Hypothermia_on_Cerebral_Autoregulatory_Vascular_Responses_in_Two_Rodent_Models_of_Traumatic_Brain_Injury_ L2 - https://www.liebertpub.com/doi/full/10.1089/neu.2011.2278?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub=pubmed DB - PRIME DP - Unbound Medicine ER -