UNIVERSITY OF MALTA
LIFE SCIENCE RESEARCH SEMINARS
Web: http://www.um.edu.mt/events/scisem/
Email: scisem@um.edu.mt
Title: A developmental study of mouse optic nerve injury during sustained
periods of oxygen-glucose deprivation
Presenter: Dr. Christian Zammit
Contact address: University of Malta
Tel: 99866747
Fax: N/A
Email: christianzammit84@gmail.com
Presentation date: 2 May 2011
Abstract
Axonal damage has recently been recognized to be a key predictor of outcome in a number
of diverse human CNS diseases, including: stroke, head and spinal cord trauma, metabolic
encephalopathies, multiple sclerosis, infections (e.g. malaria, AIDS), subcortical ischemic
damage, and other white-matter diseases (e.g. acute haemorrhagic leucoencephalitis,
leucodystrophies and central pontine myelinolysis). The main aim of this project is to shed
some light on the difference in maturation of axonal damage during sustained periods of
oxygen-glucose deprivation between different developmental stages in transgenic mouse
optic nerve.
To attain this aim we developed an in vivo experimental model to investigate the hypothesis
that the degree and nature of axonal and glial injury during ischemia vary during
development. The novelty of this study lies in the fact that to our knowledge from literature
searches, this was the first attempt to compare histologically the degree of axonal and glial
damage between the different developmental stages of white matter in the central nervous
system.
Three separate groups of mice were used: less than 20 days, 20 to 50 days, and more than
50 days old, each corresponding to a different developmental stage. Optic nerves from each
group were dissected, incubated in a Hass-Type Interphase chamber, and perfused with
aCSF bubbled with 95% O2/5% CO2 at 37oC. Varying periods of ischemia (30, 60, 90 and
120 mins) were induced by switching to a 95% N2/5% CO2 in glucose-free aCSF., After the
ischemia, the nerves were kept for a further 3 hours in the interphase chamber to assess for
any reperfusion injury,
The degree of axonal injury was assessed through confocal microscopy. To this end, the
transgenic GFP-M mice provided a distinct and rapid assessment of axon integrity, permitting
the observation of the time course of injury. Specific antibodies directed to different glial
structures were used to assess their response to ischemia: APC labeled oligodendrocytes,
NG2 labeled oligodendrocyte progenitor cells, and GFAP labeled astrocytes. Hoechst stain
was used as an apoptosis marker. Comparing the number of the different types of dead glial
cells in each condition gave us an indication of the response to ischemic injury of glial cells in
different developmental stages.
The ability to study the effect of ischemia on white matter in the brain during the different
developmental stages may lead to a better understanding of the pathophysiology of white
matter injury and hopefully, in the future, to the development of new therapeutic strategies of
the various white matter diseases.