Wild-Type Nonneuronal Cells Extend Survival of SOD1 Mutant

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domains, intracellular domain associations
would be required to bring these groups
together into an adhesive patch with a sufficient number of intercellular bonds to
resist shear forces.
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for providing facilities and support for tomographic
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Protein Data Bank with accession codes 1Q55,
1Q5A, 1Q5B, and 1Q5C. Tomographic reconstructions have been submitted to the electron microscopy database of the European Bioinformatics Institute with accession codes EMD-1051, EMD-
1052, and EMD-1053. Supported by NIH grant R01
GM47429 (P.C.).
Supporting Online Material
www.sciencemag.org/cgi/content/full/302/5642/109/
DC1
Materials and Methods
SOM Text
Figs. S1 to S5
Tables S1 and S2
Movies S1 to S3
References
19 May 2003; accepted 26 August 2003
Wild-Type Nonneuronal Cells
Extend Survival of SOD1 Mutant
Motor Neurons in ALS Mice
A. M. Clement,1,3,4* M. D. Nguyen,5† E. A. Roberts,2,3
M. L. Garcia,1,3,4 S. Boillée,1,3,4 M. Rule,6 A. P. McMahon,6
W. Doucette,7 D. Siwek,8 R. J. Ferrante,8 R. H. Brown Jr.,7
J.-P. Julien,5‡ L. S. B. Goldstein,2,3 D. W. Cleveland1,3,4§
The most common form of amyotrophic lateral sclerosis (ALS), a neurodegenerative disease affecting adult motor neurons, is caused by dominant mutations
in the ubiquitously expressed Cu-Zn superoxide dismutase (SOD1). In chimeric
mice that are mixtures of normal and SOD1 mutant– expressing cells, toxicity
to motor neurons is shown to require damage from mutant SOD1 acting within
nonneuronal cells. Normal motor neurons in SOD1 mutant chimeras develop
aspects of ALS pathology. Most important, nonneuronal cells that do not
express mutant SOD1 delay degeneration and significantly extend survival of
mutant-expressing motor neurons.
Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disorder in which
motor neurons die beginning in mid–adult life.
About 10% of cases are dominantly inherited;
about 20% of these arise from mutations in the
gene for Cu-Zn superoxide dismutase (SOD1)
(1). Transgenic mice (2–4) and rats (5, 6) that
1
Ludwig Institute for Cancer Research, 2Howard Hughes
Medical Institute and 3Department of Cellular and Molecular Medicine and 4Department of Neurosciences,
University of California, 9500 Gilman Drive, La Jolla, CA
92093–0670, USA. 5Centre for Research in Neurosciences, Research Institute of the McGill University
Health Care Centre, Montreal General Hospital, 1650
Cedar Avenue, Montreal, Quebec, Canada H3G 1A4.
6
Department of Molecular and Cellular Biology, Harvard
University, 16 Divinity Avenue, Cambridge, MA 02138,
USA. 7Day Neuromuscular Research Laboratory, Massachusetts General Hospital–East, Charlestown, MA
02139, USA. 8Departments of Neurology, Pathology,
and Psychiatry, Boston University School of Medicine,
Bedford VA Medical Center, Geriatric Research Education Clinical Center, Bedford, MA 01730, USA.
*Present address: Institute for Physiological Chemistry and Pathobiochemistry, Johannes-Gutenberg-University, Duesbergweg 6, 55099 Mainz, Germany.
†Present address: Department of Pathology, Harvard
Medical School, 200 Longwood Avenue, Boston, MA
02115, USA.
‡Present address: Centre de Recherche de l’Université
Laval (CHUL), Quebec, QC, Canada G1V 4G2.
§To whom correspondence should be addressed. Email: [email protected]
express mutant SOD1 develop a progressive motor neuron disease that shares many features with
human ALS; the complete absence of SOD1 in
mice does not cause such disease (7). Because
toxicity is neither accelerated nor ameliorated by
reducing wild-type SOD1 activity (8) and is
either unaffected (8) or enhanced (9) by increasing wild-type SOD1 activity, mutant SOD1 must
cause disease through acquisition of toxic properties. These may include aberrant oxidative
chemistry catalyzed by SOD1-bound copper
(10–14) or poisoning of a cellular process (or
processes) by abundant SOD1 protein aggregates (15–17). This triggers a cell death pathway
in motor neurons that includes activation of
caspase 3 (18, 19).
Damage to nonneuronal cells may be involved
in toxicity. Before onset of disease in SOD1 mutant mice, there is an inflammatory response, including activation of microglia (20–22) and astrocytosis (3, 20); the anti-inflammatory compound
minocycline extends survival in mouse models of
ALS (23–25), although whether this reflects action on microglia, astrocytes, or more directly on
motor neurons is not established (24). Although
accumulation of mutant SOD1 damages motor
neurons in culture (26), SOD1 mutant expression
only in neurons (27, 28) or glia (29) has not
provoked disease in mice. Thus, fundamental unanswered questions are whether motor neuron
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death is caused by toxicity of mutant SOD1 acting
solely within motor neurons, whether cells
expressing mutant SOD1 damage neighboring
wild-type motor neurons, and whether wild-type
nonneuronal cells can protect motor neurons expressing ALS-causing SOD1 mutations.
To resolve these issues, we generated chimeric
animals composed of mixtures of normal cells and
cells that express a human mutant SOD1 polypeptide at levels sufficient to cause fatal motor neuron
disease when expressed systemically in mice.
Forty-two chimeras were produced by injection of
wild-type embryonic stem (ES) cells that constitutively express yellow fluorescent protein (YFP)
(30) into SOD1G85R (line 148) (3) or SOD1G37R
(line 42) (4) mutant blastocysts (Fig. 1, A and B).
Percent chimerism (ranging from ⬃5 to ⬃90%
wild-type cells) was determined by multiple mea-
sures (table S1), including assessment of coat
color, immunoblotting of tail extracts for accumulation of mutant SOD1 and YFP (Fig. 1B), and by
the proportion of cross-sectional area in spinal
cords with detectable YFP (Fig. 1, C and D).
Wild-type and SOD1 mutant–expressing cells
contributed to multiple cell types (fig. S1).
An additional 23 chimeras (Fig. 1H) were
produced by using aggregation (31) of morulae
from wild-type embryos with morulae carrying
transgenes for another mutant SOD1 (SOD1G93A)
(2) and for ubiquitously expressed ␤-galactosidase
(lacZ) (32). Comparable estimates were obtained
for the amount of mutant SOD1 by using either
coat color or immunohistochemistry of spinal
cord sections to identify cells expressing lacZ. For
example, animals determined to be ⬃50% chimeric by coat color had a corresponding ⬃50% of
Fig. 1. Wild-type cells increase survival of mice expressing ALS-linked SOD1
mutations. (A) Chimeras generated by injection of E-YFP– expressing ES cells
into blastocysts of SOD1G85R or SOD1G37R transgenic mice. (B) Degree of
chimerism determined by immunoblotting of tail extracts from mice in (A)
with antibodies having equal affinity for human and mouse SOD1 (3, 4) or to
GFP. Spinal cord sections from mice with (C) low and (D) high contribution
of wild-type cells identified with a GFP antibody (green). DH, Dorsal horn;
VH, ventral horn. (E and F) Delayed onset of disease and extended survival of
SOD1 mutant chimeras. (E) Disease onset and (F) survival times for
SOD1G37R/YFP chimeras. (G) All wild-type cells or all neurons, respectively,
identified in lumbar spinal cord sections of SOD1G37R/YFP chimeras identified with GFP (green) or neurofilament (red) antibodies. Ages shown are at
end-stage disease. (H to K) Chimeras generated by aggregation of morulas
114
spinal cord areas expressing lacZ, including large
spinal motor neurons (Fig. 1I). For comparison,
spinal cord sections from wild-type and germline
SOD1G93A mice are unstained or completely
stained for lacZ (Fig. 1, J and K).
The presence of wild-type cells in the
SOD1G37R/YFP and SOD1G85R/YFP chimeras
delayed disease onset with average extensions
of 1.6 months (P ⫽ 0.0033; n ⫽ 17; one tailed
Mann-Whitney test) for SOD1G85R and 1.2
months (P ⫽ 0.0007, n ⫽ 17) for SOD1G37R
chimeras (Fig. 1E). Compared with germline
SOD1 mutant mice, there was an average extension of life-span of 1.8 months (P ⫽ 0.04,
n ⫽ 13) for SOD1G85R and 1.1 months (P ⫽
0.0001, n ⫽ 17) for SOD1G37R chimeras with a
maximum delay of 7.8 and 3.3 months, respectively; Fig. 1F). Both measures correlated well
from normal mice and mice heterozygous for SOD1G93A and lacZ transgenes.
(H to J) Spinal cords from a (I) chimera, ( J) wild-type mouse, and (K)
germline SOD1G93A, lacZ mouse after hematoxylin-and-eosin staining and
assay for lacZ (brown). Black and white arrows point to mutant and
wild-type neurons, respectively. (L) Survival versus age for SOD1G93A/lacZ
chimeras and germline SOD1G93A animals. (M) Survival of SOD1G93A/lacZ
chimeras versus percent wild-type cells. (N and O) SOD1G93A mutant motor
neurons identified in ventral horns of a SOD1G93A/lacZ chimera (N) versus
a germline SOD1G93A mouse (O). Mutant cells were identified by antibodies
specific for human SOD1 (green) (3, 4); neurons were identified with a
neurofilament antibody (SMI32) (red). Wild-type motor neurons (red arrows); SOD1G93A mutant– expressing motor neurons (white arrows). A nonneuronal, SOD1G93A-expressing cell is marked by an asterisk.
3 OCTOBER 2003 VOL 302 SCIENCE www.sciencemag.org
REPORTS
with the proportion of wild-type (YFP-expressing) cells within each spinal cord (Fig. 1G).
A robust extension in life-span was also seen
in the SOD1G93A/lacZ chimeras. Eleven of the 23,
including 5 with ⬍30% contribution from wildtype cells, survived disease-free until they were
killed at ⬎10 months of age (Fig. 1, L and M), an
age at least twice that of the longest lived germline
SOD1G93A littermates (Fig. 1L). Examination of
spinal cord and motor roots of two of these revealed that 67% (chimera 45; Fig. 1N) and 77%
(chimera 67) of motor neurons contained mutant
SOD1, but there was no degeneration or axonal
loss in thoracic roots of either chimera and only
the earliest signs of degeneration in some lumbar
roots of chimera 67. This contrasts with germline
SOD1G93A animals in which 100% of the motor
neurons express mutant SOD1 (Fig. 1O), and half
of these are lost by 5 months (2).
Extended survival of mutant-expressing motor neurons was also seen in chimeras generated
by aggregation of morulae from a SOD1G37R
transgenic line (line 29, which has a later disease
onset) (4) with morulae whose wild-type neurons
were marked by expression of very low levels of
the smallest human neurofilament subunit
(hNF-L) (33) (Fig. 2A). Immunoblots for the
G37R
mutant and hNF-L in spinal cord
SOD1
extracts revealed ⬃30 and ⬃90% mutant cells in
two SOD1G37R/hNFL chimeras (Fig. 2B). Chimera 7, with the higher wild-type content, did not
develop disease even 5 months beyond the age of
the longest-lived germline SOD1G37R mice. As
seen with antibodies specific for human SOD1
(fig. S2), hNF-L, or all neurofilaments (to identify mutant and wild-type axons), 30% of ventral
root axons (Fig. 2, C to E) were mutant. However, there was no sign of axonal degeneration or
loss in the L5 ventral root (Fig. 2F), in which 978
axons remained, a number consistent with the
927 ⫾ 99 (n ⫽ 26) seen in age-matched wildtype mice. Furthermore, in contrast to parental
SOD1G37R mice (Fig. 2, H, K, and N), even the
earliest pathologic signs of disease, including
astrocytosis and microgliosis, were absent in this
chimera (Fig. 2, I, L, and O), just as they were in
normal mice (Fig. 2, G, J, and M).
Extended survivals of SOD1 mutant–
expressing motor neurons in the chimeras could
arise, at least in part, from a protective effect of
wild-type motor neurons. To test this, two
SOD1G37R/YFP chimeras were identified that
developed without wild-type motor neurons; all
motor neurons of multiple lumbar levels (Fig. 3, B
Fig. 2. Absence of motor
neuron pathology or degeneration despite 30%
SOD1G37R
mutant–
expressing motor neurons. (A) Chimeras generated by aggregation of
morulas derived from
hNF-L and SOD1G37R
(line 29) mice. (B) Chimerism was determined
by immmunoblotting
spinal cord extracts with
antibodies to hNF-L, actin, and human/mouse
SOD1. The amount of
hNF-L is a measure for
the contribution of
wild-type neurons. (C
to F) Sections of an
L5 ventral root of
SOD1G37R/hNF-L chimera 7 simultaneously
labeled for (C) neurofilaments
(antibody
SMI-32) and (D) human
SOD1 (3, 4). (E) The genotype of all axons in
the same root were
identified as in (C and
D) with antibodies specific for human SOD1
(green), hNF-L (red) (to
identify wild-type axons), and myelin basic
protein (blue). (F) No
sign of neurodegeneration was visible in a
toulidine blue–stained,
semithin section of the same root. (G to O) Spinal cord sections of (G, J, and M) wild-type, (H, K, and
N) SOD1G37R (line 29), and (I, L, and O) chimera 7 immunostained with antibodies against MAC-2 (G
to I), glial fibrillary acidic protein (GFAP) ( J to L), and cyclin-dependant kinases (Cdk1, 2, 3) (M to O),
which are markers of activated microglia, astrocytes, and proliferating cells, respectively.
and C, arrows) and motor roots (Fig. 3E)
accumulated mutant SOD1. Both of these
also displayed a striking left-right asymmetry
in the proportion of wild-type (YFP-positive)
Fig. 3. Wild-type cells that are not motor neurons
extend survival of SOD1 mutant motor neurons. (A)
Number of ventral horn motor neurons on both
sides of the lumbar spinal cord was determined for
germline SOD1G37R mice, age-matched wild-type
mice, and two chimeras with asymmetric distribution of wild-type cells (n ⱖ 4 sections per animal).
(***P ⱕ 0.001 with Student’s t test for paired
samples; error bars are SEM). (B) Lumbar spinal
section demonstrating an asymmetric distribution
of wild-type (green, GFP-immunopositive) cells. (C)
Higher power view of (B). Motor neurons are mutant (blue, stained with a human-specific SOD1
antibody), not wild type (GFP-specific antibody,
green). (D) Asymmetric loss of large-caliber axons
seen in toluidine blue–stained semithin sections of
left and right L5 ventral roots of chimera 646. (E)
Triple-immunofluorescence staining for (green)
wild-type YFP-expressing cells, (red) mutant human
SOD1, and (blue) myelin in an L5 ventral root of
chimera 646. Green staining of a wild-type Schwann
cell body (left) serves as a positive control for detection of YFP-containing wild-type cells. Examination of the entire root revealed that all axons were
mutant bearing (red) (fig. S2 for roots from other
chimeras stained contemporaneously).
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nonneuronal cells in the two halves of their
spinal cords. Germline SOD1G37R mice at endstage disease uniformly exhibit symmetric loss
of two-thirds of their large motor neurons in
both halves of the lumbar spinal cord (Fig. 3A).
However, although all motor neurons were mutant in these two SOD1G37R/YFP chimeras,
there was an asymmetric loss of motor neurons
(Fig. 3A; P ⬍ 0.001; paired Student’s t test with
n ⬎ 4 sections per animal) and axons, with
more than twice as many large-caliber (⬎3.5
␮m diameter) surviving axons (Fig. 3D; 187 on
the left versus 89 on the right) in the lessaffected side. In both chimeras, the side with
higher neuronal survival had a higher proportion (25 versus 2% in chimera 646; 30 versus
10% in chimera 213) of wild-type (YFPexpressing) nonneuronal cells throughout the
lumbar cords. Thus, even when all motor neurons are mutant, an environment having a higher proportion of wild-type, nonneuronal cells
reduces motor neuron mortality.
To assess whether SOD1 mutant nonneuronal
cells can influence neighboring wild-type neurons, spinal cord sections of chimeric animals
were analyzed at end-stage disease for pathologic
signs of neurodegeneration. A hallmark for damage to neurons in human patients is the appearance of ubiquitin-positive protein aggregates (34,
35). These are also seen as an early sign for
damaged neurons in SOD1G85R (3, 8) and
SOD1G37R (4) mice, but do not appear in motor
neurons of wild-type mice (Fig. 4, A to C). Ubiquitin aggregates appear in neuronal processes and,
less prominently, in cell bodies (Fig. 4B; fig. S3).
Similar ubiquitinated epitopes were never seen in
age-matched wild-type littermates (Fig. 4A; fig.
S3). In contrast, in both SOD1G37R and
SOD1G85R chimeras (n ⫽ 4), some wild-type
neurons (YFP-containing; arrows in Fig. 4, D and
E, and G and H) in end-stage chimeras accumulated ubiquitinated epitopes in neuronal processes
(Fig. 4F, arrows) and cell bodies (Fig. 4I, arrow),
which indicates that a deficit in ubiquitin-dependent protein degradation is acquired by these wildtype neurons. The intensity of such ubiquitin
staining in wild-type axons (Fig. 4F, arrows) and
motor neuron cell bodies (Fig. 4I, arrow) frequently exceeded that of neurons expressing mutant
SOD1 (Fig. 4F, boxed areas; Fig. 4I).
We found that expression of mutant SOD1
in motor neurons at levels that cause disease in
parental mice is not sufficient to trigger their
degeneration or the development of pathologic
abnormalities. Rather, wild-type nonneuronal
cells, in some cases representing a small minority of total cells, can ameliorate degeneration
and death of SOD1 mutant–expressing motor
neurons compared with those in parental SOD1
mutant mice. That SOD1 mutant neurons survive longer when surrounded by a wild-type
environment supports the view that damage to
adjacent nonneuronal cells by mutant SOD1 is a
major contributor to disease caused by SOD1
mutations. Damaged glial cells and neurons,
therefore, could act in concert to provoke disease, consistent with failure of mutant expression in single cell types to induce motor neuron
degeneration (27–29). It is also consistent with
the failure of increased levels of mutant SOD1
within neurons to accelerate disease caused by
ubiquitous expression of SOD1G93A (28). Indeed, we know of no compelling in vivo evidence that the genotype of the motor neurons
themselves has any bearing on the probability of
their death in ALS; motor neuron death could in
principle be provoked solely by damage to multiple types of adjacent cells such as interneurons,
astrocytes, and microglia. Further work is critical
to evaluate this possibility.
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
Fig. 4. Acquisition of abnormal ubiquitination in wild-type neurons adjacent to SOD1 mutant–expressing
cells. Confocal micrographs of spinal cord cross sections from the lumbar region of (A) normal (C57/B6), (B)
SOD1G85R (line 148), and (C) SOD1G37R (line 42) mice after staining with (red) neurofilament (SMI32) and
(blue) ubiquitin antibodies. Ubiquitin-containing aggregates in neuronal processes (arrows) are present in
SOD1G85R and SOD1G37R germline animals, as well as in the cell bodies (block arrow). (D to I) Triple labeling
of spinal cord sections from (D to F) SOD1G37R and (G to I) SOD1G85R chimeras stained with (D and G) SMI32
to identify neurons (red), (E and H) GFP to detect wild-type cells (green), and (F and I) ubiquitin (blue). Arrows
in (D to F) point to a wild-type axon with elevated levels of ubiquitin compared with a mutant axon
highlighted in the boxed region. Arrow in (G to I) points to a wild-type neuronal cell body with high ubiquitin
accumulation compared with an adjacent SOD1G85R motor neuron. Additional examples are in fig. S3.
116
24.
25.
26.
27.
28.
29.
30.
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36. We gratefully acknowledge A.-K. Hadjantonakis (Columbia University, New York, NY ) and A. Nagy (Mount
Sinai Hospital, Toronto) for providing the E-YFP-ES cells;
P. Hince and D. Houle for their technical help; and J.
Folmer ( Johns Hopkins, Baltimore, MD). This work was
supported by the grants from the NIH (NS 27036 to
D.W.C, HD 30249 to A.P.M., AG 13846 to R.J.F., AG
12992 to R.H.B. and R.J.F, and NS 31248 and NS 37912
to R.H.B.); the Center for ALS Research at Johns Hopkins
(to D.W.C and L.S.B.G.); the ALS Association (to A.P.M.
and R.H.B.); the Canadian Institutes of Health Research
(CIHR) (to J.-P.J.); the Angel Fund for ALS Research; and
Project ALS (to R.H.B.); and the Veterans Administration
(R.J.F.). A.M.C. was supported in part by a fellowship
from the German Research Council (DFG, Cl-175).
M.D.N. is a recipient of a K. M. Hunter/CIHR Scholarship.
M.L.G. is the recipient of a postdoctoral fellowship from
the NIH. S.B. is a recipient of a Fondation pour la
Recherche Medicale fellowship. J.-P.J. is a recipient of a
Thalamic Control of Visceral
Nociception Mediated by T-Type
Ca2ⴙ Channels
Daesoo Kim, Donghyun Park, Soonwook Choi, Sukchan Lee,
Minjeong Sun, Chanki Kim, Hee-Sup Shin*
Sensations from viscera, like fullness, easily become painful if the stimulus persists. Mice
lacking ␣1G T-type Ca2⫹ channels show hyperalgesia to visceral pain. Thalamic infusion
of a T-type blocker induced similar hyperalgesia in wild-type mice. In response to
visceral pain, the ventroposterolateral thalamic neurons evoked a surge of single spikes,
which then slowly decayed as T type–dependent burst spikes gradually increased. In
␣1G-deficient neurons, the single-spike response persisted without burst spikes. These
results indicate that T-type Ca2⫹ channels underlie an antinociceptive mechanism
operating in the thalamus and support the idea that burst firing plays a critical role in
sensory gating in the thalamus.
Low voltage–activated (LVA) T-type Ca2⫹ channels play crucial roles in the control of cellular
excitability under diverse physiological and
pathological processes (1, 2). Recently, studies
revealed a novel role of T-type Ca2⫹ channel in
the pain sensory pathway by showing that this
channel facilitates pain signals in peripheral nociceptors (3, 4) and in the spinal cord (5). T-type
channels are also highly expressed in the thalamus
(6), through which noxious signals from the spinal cords must pass before reaching the cortex (7).
When the thalamocortical relay neurons receive
sensory inputs, they respond in dual firing
modes: either in singular action potentials or in
a burst of action potentials clustered together as
a high-frequency discharge (8–10). T-type
Ca2⫹ channels are known to excite hyperpolarized thalamic neurons to generate bursts of
action potentials. There has been much debate
about the role of the thalamic burst firing in the
sensory processing (11, 12). Therefore, whether
thalamic T-type channels would contribute to
the nociceptive signal processing as a signal
enhancer or a suppressor is an open question.
CIHR Senior Investigator Award. D.W.C. receives salary
support from the Ludwig Institute for Cancer Research.
L.S.B.G. is an Investigator of the Howard Hughes Medical Institute.
Supporting Online Material
www.sciencemag.org/cgi/content/full/302/5642/113/
DC1
Materials and Methods
Figs. S1 to S4
Table S1
References and Notes
24 April 2003; accepted 13 August 2003
Mice homozygous for a null mutation of the
␣1G (CaV3.1) gene showed a functional deletion
of T-type currents and lacked low threshold burst
firing in the thalamocortical relay neurons (13).
We measured the sensitivity of the ␣1G-deficient
mice (␣1G–/–) by delivering thermal or mechanical stimuli delivered either on the palm or tail
(supporting online material). No significant difference was observed between the mutants and their
wild-type littermates in these assays (Fig. 1, A to
C). Hyperalgesia to cutaneous pain, as measured
by the relative enhancement of the pain response
by a subcutaneous injection of complete Freund’s
adjuvant (CFA) before pain tests (14), also did not
significantly differ between the wild type and the
mutant (Fig. 1D). Next, we examined the sensitivity of the mice to visceral pain induced by
intraperitoneal administration of either acetic acid
(Fig. 1E) or MgSO4 solution (Fig. 1F) as previously described (15). The wild-type mice showed
typical pain behaviors characterized by writhing,
such as abdominal stretching and constriction in
response to these two chemicals, with MgSO4induced pain responses terminated earlier than
those by acetic acids (15). However, compared
National Creative Research Initiative Center for Calcium and Learning, Korea Institutes of Science and
Technology, Seoul 136-791, Korea.
*To whom correspondence should be addressed. Email: [email protected]
Fig. 1. Pain responses
of ␣1G⫺/⫺ mice to
noxious stimuli. (A)
Responses to mechanical stimuli with von
Frey filaments. (B) Tail
flick responses to thermal stimuli. (C) Paw
withdrawal responses
to infrared thermal
stimuli at two different intensities. (D) One day after injection of CFA (1⫻) in the left paw, infrared
thermal stimuli were delivered either to the injected paw (ipsilateral) or the opposite
uninjected paw (contralateral). Visceral pain induced by intraperitoneal injection of
either acetic acid (E) or MgSO4 solution (F). Writhing responses were examined for 20
min after acetic acid injection or for 10 min after MgSO4 injection. Error bars indicate
SEM. Two-tailed t test, *P ⬍ 0.01; **P ⬎ 0.05.
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C O R R E C T I O N S A N D C L A R I F I C AT I O N S
ERRATUM
post date 24 October 2003
REPORTS: “Wild-type nonneuronal cells extend survival of SOD1 mutant motor neurons in ALS mice” by A. M. Clement et al. (3 Oct. 2003,
p. 113). The word “inherited” was deleted from the first sentence of
the abstract. It should read as follows: “The most common inherited
form of amyotrophic lateral sclerosis (ALS), a neurodegenerative disease affecting adult motor neurons, is caused by dominant mutations
in the ubiquitously expressed Cu-Zn superoxide dismutase (SOD1).”
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SCIENCE
Erratum post date 24 OCTOBER 2003
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