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Research Highlight

Differences in stroke damage in aged mice may

not be due to differential cerebral blood flow

dynamics

Venugopal Reddy Venna , Louise D. McCullough 1,2,3
1
1 Department of Neuroscience, University of Connecticut Health Center, Farmington, CT 06030, USA.
2 Department of Neurology, University of Connecticut Health Center, Farmington, CT 06030, USA.
3 The Stroke Center at Hartford Hospital, Hartford, CT 06102, USA.

Manwani B, Friedler B, Verma R, Venna VR, McCullough LD, Liu F. and only examines blood flow changes in a small region
Perfusion of ischemic brain in young and aged animals: a laser speckle of the brain. As aging leads to several morphological
flowmetry study. Stroke 2014;45(2):571‑8.
and pathological changes throughout the vasculature,
INTRODUCTION leading to atherosclerosis and small vessel disease,
these changes cannot be identified by LDF. These
Stroke is the leading cause of death and adult disability. [1-3] alterations might contribute to significant stroke damage
Aging is the most important nonmodifiable risk factor variability in aged animals. Unlike LDF, laser speckle
for stroke, and aged patients exhibit impaired stroke flowmetry (LSF) provides a broader spatial, and temporal
recovery. Consistent with clinical data, findings from pattern of blood flow changes in the brain, allowing
[4]
animal models have demonstrated that aged mice have investigators to better examine and control cerebral
higher mortality and worse outcomes when subjected to blood flow changes during and following occlusion.
same duration of occlusion compared with young mice,
yet paradoxically, the infarct damage is smaller in the aged COMMENT
mice. [5,6] Impaired recovery has been linked to several
underlying mechanisms, including altered peripheral To determine if the discrepancies in histological outcomes
immune responses, enhanced neuroinflammation, and in aged mice were secondary to variability or differences
reductions in neurogenesis. [7-9] However, it was not in blood flow dynamics, we first assessed whether aged
known whether the discrepancy in histological outcome mice exhibited differential blood flow patterns after
is associated with age-induced changes in the cerebral stroke compared to young mice using LSF. A structural
vasculature or cerebral blood flow. immunohistochemical analysis of the vasculature
was also performed by perfusing blood vessels with
Consistent blockage of blood flow is essential to achieve fluorescein isothiocyanate-dextran and co-labeling with
a homogenous ischemic infarct. Previous animal studies the CD31 antibody. No significant difference in blood
use laser Doppler flowmetry (LDF) to confirm blood flow dynamics or microvascular density was observed
flow blockage after ischemic occlusion. However, this between young (3-month-old) and aged (18-month-old)
technique has often been criticized as it not quantitative animals after middle cerebral artery occlusion (MCAO).

Access this article online Although these results refute the hypothesis that
Quick Response Code: changes in cerebral blood flow or vascular density
Website: was responsible for the smaller infarcts in aged mice,
www.nnjournal.net
the study has provided some very interesting findings.
DOI: Based on the LSF data, focal ischemia during MCAO
10.4103/2347-8659.135569 induced a dramatic blood flow drop to the ipsilateral
hemisphere as expected, but it was also associated with

Corresponding Author: Dr. Louise D. McCullough, Department of Neuroscience, University of Connecticut Health Center,
263 Farmington Avenue, Farmington, CT 06030, USA. E‑mail: lmccullough@uchc.edu

Neuroimmunol Neuroinflammation | Volume 1 | Issue 1 | June 2014 13