Volume 5 • Number 1 • 2006 A Journal of Acute and Emergency Care
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Eelco F. M. Wijdicks, MD
The Official Journal of the
ISSN 1541–6933 (Print) ISSN 1556–0961 (Online)
Indexed and Abstracted in Index Medicus and MEDLINE
*Correspondence and reprint
Daniel T. Laskowitz
Duke University Medical Center
Durham, NC 27710
Patients with brain injury have an in-
creased risk of seizures, which may be
especially detrimental in the acute care
setting. In particular, patients with sub-
arachnoid hemorrhage (SAH) and trau-
Objectives: Prophylactic treatment with antiepileptic drugs is common practice following
subarachnoid hemorrhage (SAH) and traumatic brain injury. However, commonly used
antiepileptic drugs have multiple drug interactions, require frequent monitoring of serum
levels, and are associated with adverse effects that may prompt discontinuation. In the
current study, we test the hypothesis that levetiracetam, an anticonvulsant with favorable
interaction and adverse event profiles, is neuroprotective in clinically relevant models of
SAH and closed head injury (CHI).
Methods: A single intravenous dose of vehicle, low-dose (18 mg/kg), or high-dose
(54 mg/kg) levetiracetam was administered intravenously followed CHI. Functional
assessments were performed on a daily basis, and histological assessments performed at
24 hours. In a separate series of experiments, mice were randomized to receive intravenous
administration of vehicle, low-dose, or high-dose levetiracetam every 12 hours for 3 days
following SAH. Functional endpoints were assessed daily, followed by measurement of
MCA luminal diameter on day 3.
Results: A single dose of levetiracetam improved functional and histological outcomes
after CHI. This effect appeared specific for levetiracetam and was not associated with
fosphenytoin treatment. Treatment with levetiracetam also improved functional outcomes
and reduced vasospasm following SAH.
Conclusion: Levetiracetam is neuroprotective in clinically relevant animal models of SAH
and CHI. Levetiracetam may be a therapeutic alternative to phenytoin following acute
brain injury in the clinical setting when seizure prophylaxis is indicated.
Key Words : Subarachnoid hemorrhage ; traumatic brain injury ; posttraumatic epilepsy ;
levetiracetam ; vasospasm ; neuroprotection.
(Neurocrit. Care 2006;05:71–78)
Levetiracetam is Neuroprotective in Murine Models of Closed
Head Injury and Subarachnoid Hemorrhage
Haichen Wang ,1, 2 Junling Gao ,1 – 5 Timothy F. Lassiter ,3 David L . McDonagh ,1, 2 , 4 Huaxin Sheng ,1 ,4 David S. Warner ,1, 4
John R . Lynch ,1, 2 and Daniel T. Laskowitz* ,1 ,2 ,4
1 Multidisciplinary Neuroprotection Laboratories, and the 2 Departments of Medicine (Neurology), 3 Pharmacy,
and 4 Anesthesiology, Duke University Medical Center, Durham, NC; 5 Department of Histology and Embryology,
North China Coal Medical College, Tangshan, Hebei, China
matic brain injury accompanied by loss
of consciousness, depressed skull frac-
ture, parenchymal contusion, or pro-
longed amnesia may be at high risk of
seizures in the acute care setting. For
these reasons, antiepileptic drug (AED)
Copyright © 2006 Humana Press Inc.
All rights of any nature whatsoever are reserved.
ISSN 1541-6933/06/5:71–78 ISSN 1556-0961 (Online)
DOI: 10.1385/Neurocrit. Care 2006;05:71–78
72 Wang et al.
♦ Volume 5, 2006
prophylaxis is a common practice and has been incorpo-
rated into the standard of care in many neurocritical care
units (1,2) . However, the prophylactic use of anticonvul-
sant drugs is often associated with the need for frequent
monitoring of drug levels, as well as the possibility of
drug interactions and adverse events.
Phenytoin is often considered the agent of choice for
seizure prophylaxis because of its ease of administra-
tion. Disadvantages of prophylactic phenytoin use in-
clude its association with allergic reactions (predomi-
nantly rash), drug fever, thrombocytopenia, hepatitis,
cardiovascular toxicities, and fluctuating serum levels
that require frequent monitoring and dose adjustments
(3 – 5) . Fosphenytoin is a phenytoin prodrug that is asso-
ciated with a much higher cost, but lower incidence of
symptomatic hypotension and bradyarrhythmias dur-
ing intravenous administration (6) . However, both of
these agents are associated with numerous drug interac-
tions, and the association between phenytoin and ad-
verse reactions such as thrombocytopenia, fever, and
rash may lead to early discontinuation. Moreover, recent
observations suggest that exposure to phenytoin may be
associated with impaired functional outcomes when
used in the management of aneurysmal SAH (7) .
Given these concerns, there remains a clinical need
for an agent with reduced drug interactions, need for
monitoring, and adverse events. Levetiracetam belongs
to the pyrrolidine class of drugs, and was approved in
1999 as an adjunct in the treatment of partial complex
seizures. Interestingly, levetiracetam has a different anti-
convulsant profile from most other AEDs, and has no ef-
fect on the maximal electroshock or pentylenetrazol
models which are traditionally used in the screening of
anticonvulsant candidates (8) . Levetiracetam has mini-
mal drug interactions, and there is no interaction with
hepatic CYP450 enzymes (9) . Although adverse effects
are infrequent, administration of levetiracetam may be
associated with agitation and emotional lability, and
should be monitored closely in patients with psychiatric
conditions (10) .
Preliminary data also suggest that levetiracetam may
be neuroprotective in the setting of acute brain injury. In
an in vitro hippocampal slice paradigm, levetiracetam
reduced high voltage activated calcium currents, and re-
versed the inhibition of negative allosteric modulators of
? -aminobutyric acid and glycine-gated currents (11) .
These results were recently extended to a rodent model
of focal ischemia, where intraperitoneal administration
of levetiracetam was associated with a dose-dependent
reduction in infarct volume (12) . However, this was not
a study that could be easily translated into the clinical
setting, as drug was administered prior to ischemic in-
jury. In the current study, we assessed whether post-
insult intravenous administration of levetiracetam is
associated with histological or functional improvement
in previously validated murine models of closed head
injury (CHI) and SAH (13 – 15) .
These studies were approved by the Duke University
Animal Care and Use Committee. The care and handling
of the animals comply with National Institutes of Health
Closed Head Injury Model
This murine CHI model (13,14) was adapted from a
previously described model of closed cranial trauma for
the rat (16,17) . Twelve- to fourteen-week-old C57Bl/6J
male mice (Jackson Laboratories, Bar Harbor, ME) were
used. The trachea was intubated after anesthesia induc-
tion with 4.6% isoflurane and the lungs were mechani-
cally ventilated with 1.6% isoflurane in 30% O 2 /70% N 2 .
Rectal temperature was maintained at 37ºC. The animal
was positioned in a stereotactic device, the scalp was in-
cised and the skull exposed. A concave 3-mm metallic
disc was glued to the skull immediately caudal to
bregma. A 2.0-mm diameter pneumatic impactor (Air-
Power, Inc. High Point, NC) was used to deliver a single
midline impact to the disc surface. The impactor was
discharged at 6.8 ± 0.2 m/second with a head displace-
ment of 3 mm. After impact, the animals were allowed
to recover spontaneous ventilation and the tracheas
were extubated. Following recovery, mice were allowed
free access to food and water.
Immunohistochemistry: Fluoro-Jade B Staining
Sagittal sections (40 µ m) were cut on a vibratome, col-
lected in cryoprotectant solution containing ethylene
glycol, sucrose, and sodium phosphate. Every eighth
section was mounted onto a charged slide and stained
with Fluoro-Jade B (18) to mark degenerating neurons.
Slides were immersed in 100% ethanol for 3 minutes
followed by 1 minute in 70% alcohol and 1 minute in
distilled water. The slides were then transferred to a so-
lution of 0.06% potassium permanganate for 15 minutes
followed by a 1-minute rinse in distilled water. Slides
were then stained in a 0.001% Fluoro-Jade B (Histochem,
Jefferson, AR) solution prepared in 0.1% acetic acid for
30 minutes, the slides were rinsed for 1 minute in dis-
tilled water three times. Slides were then dried over-
night in the dark. The following day, the slides were
cleared by immersion in xylene and coverslipped with
DPX (Fluka, Milwaukee, WI). Slides containing hippo-
campus were examined for degenerating neurons using
an epifluorescent microscope (Nikon, Japan) with a me-
dium band blue excitation (Nikon B-2A, 450 – 490 nm)
filter set. Degenerating neurons were quantified at ×20
magnification by counting the total number of Fluoro-
Jade B-positive neurons in every eighth section of brain
Levetiracetam is Neuroprotective 73
♦ Volume 5, 2006
hippocampus by an observer blinded to group
Subarachnoid Hemorrhage Model
SAH was induced as previously described (15,19,20) .
Twelve- to fourteen-week-old C57Bl/6J male mice
(Jackson Laboratories, Bar Harbor, ME) were induced in
a chamber with 4.6% isoflurane. The trachea was intu-
bated and anesthesia maintained by ventilation with
1.6% isoflurane in 30% O 2 /70% N 2 . The right common
carotid was exposed by a midline neck incision.
Following isolation and ligation of the external carotid
artery (ECA), a blunted 5-0 monofilament (Ethicon,
Somerville, NJ) nylon suture was inserted into the ECA
and advanced distal to the right anterior cerebral artery
(ACA)–middle cerebral artery (MCA) bifurcation to per-
forate the right ACA. The suture was then withdrawn,
allowing reperfusion and SAH. In sham-operated mice
the monofilament was advanced without perforation.
After removal of the filament, the skin was closed with
4-0 suture (Surgical Specialties, Reading, PA) and isoflu-
rane was discontinued. After recovery of spontaneous
ventilation, the trachea was extubated, and mice were
allowed free access to food and water.
Cerebral Vascular Casting and MCA Luminal
Measurement After SAH
Cerebral vascular casting was performed 72 hours
after SAH as previously described (15,19,20) . Three days
following SAH, mice were intubated after induction
with 4.6% isoflurane. A thoracotomy was performed to
allow cannulation of the proximal aorta. Flexible plastic
tubing (0.76-mm internal diameter, Helix Medical,
Netherlands) was used to deliver infusion solutions by
manual pulsatile syringe pressure (60 – 80 mmHg).
Physiological saline (20 mL) was infused followed by
30 mL of 10% formalin and 5 mL of gelatin-India ink
solution passed through a 0.2- µ m filter. The proximal
aorta and vena cava were ligated following gelatin ink
infusion to prevent leaking. The body was then refriger-
ated for 24 hours to allow gelatin solidification, after
which the brain was harvested and stored in 4% for-
maldehyde. The MCA was imaged using a video camera
linked to a dissecting microscope controlled by an
image analyzer (MCID-M5, Imaging Research Inc., St.
Catherine’s, Ontario, Canada). The narrowest diameter of
the MCA observed within 1-mm distal to the ACA – MCA
bifurcation was determined by digital measurement.
In the CHI paradigm, a single intravenous adminis-
tration of either vehicle or drug was administered by tail
vein 30 minutes following pneumatic impact. In the
SAH model, vehicle or drug was administered immedi-
ately after SAH and at 12-hour intervals for the first
3 days as previously described.
Testing of Functional Deficits
An automated rotarod (Ugo Basile, Comerio, Italy)
was used to assess vestibulomotor function (14) . On the
day prior to CHI, mice underwent two consecutive con-
ditioning trials at a set rotational speed (16 rpm) for 60
seconds and then three additional trials with an acceler-
ating rotational speed. The average time to fall from the
rotating cylinder in the latter three trials was recorded
as baseline latency. On days 1 – 5 post-CHI, the mice had
three consecutive daily trials with accelerating rotational
speed (intertrial interval = 15 minutes). The average la-
tency to fall from the rod was recorded. Mice unable to
grasp the rotating rod were given a latency value of
Functional deficit (3 – 21) was also assessed daily by
an examiner blinded to group assignment, as we have
described previously (20) . The motor component score
was derived from spontaneous activity, symmetry of
limb movements, climbing, and balance and coordina-
tion with each activity scored on a 0 – 3 scale. The sensory
component score was derived from examination of body
proprioception, vibrissae, and tactile responses, with
each component scored on a 1 – 3 scale. A score of 21 rep-
resented normal function.
Serial tests of functional performance, including ro-
tarod performance and clinical severity scores, were
compared with repeated measures analysis of variance
(ANOVA) with time as the repeated variable and using
Dunnett’s post hoc method for correcting multiple com-
parisons. The numbers of Fluoro-Jade B positive cells
and neurological scores were compared among groups
with the Kruskal – Wallis H statistic. Between groups, dif-
ferences were compared by the Mann – Whitney U statis-
tic. MCA luminal diameters were compared with
one-way ANOVA. Parametric values are expressed as
mean ± standard deviation (SD). Significance was
assumed if p < 0.05.
Levetiracetam is Associated With Improved
Functional and Histological Outcomes
To assess whether administration of levetiracetam re-
duced functional deficit in a clinically relevant paradigm
of CHI, mice were randomized after injury to receive a
single intravenous injection of high-dose levetiracetam
(54 mg/kg; n = 14); low-dose levetiracetam (18 mg/kg;
n = 14), or saline control ( n = 9). Although levetiracetam
74 Wang et al.
♦ Volume 5, 2006
is not dosed by weight clinically, these doses were cho-
sen as they are in the range commonly used in clinical
practice (1000 – 3000 mg. daily, delivered in divided
doses). Treatment with high-dose levetiracetam was as-
sociated with a significant improvement in vestibulo-
motor function as assessed by rotarod as compared to
low-dose levetiracetam or control animals. This effect
was sustained throughout the 5-day testing period. The
performance of animals treated with lowdose levetirace-
tam was not significantly different than control mice
treated with vehicle ( Figure 1A ).
To address whether this beneficial effect of levetirace-
tam was nonspecific and caused by early suppression of
seizures, we performed a parallel experiment with fos-
phenytoin. As before, mice were randomized into three
groups following CHI. Thirty minutes following impact,
mice received a single intravenous administration of
either vehicle ( n = 14), a standard therapeutic loading
dose of fosphenytoin (18 mg/kg phenytoin equivalents;
n = 14), or high-dose fosphenytoin (54 mg/kg phenytoin
equivalents; n = 15). Interestingly, although admini-
stration of 18 mg/kg fosphenytoin did not have any
beneficial effect in this model, high-dose fosphenytoin
was associated with impaired motor performance that
was sustained throughout the 5-day testing period
( Figure 1B ).
To assess whether the beneficial effects of levetirace-
tam on functional performance were associated with
histological evidence of neuroprotection, we performed
CHI on a separate cohort of animals ( n = 8) that received
a single intravenous dose of vehicle ( n = 8), low-dose
levetiracetam (18 mg/kg; n = 7), or high-dose levetirace-
tam (54 mg/kg; n = 7). At 24 hours after injury, animals
were euthanized. Hippocampal sections were stained
with Fluoro-Jade B to quantify the magnitude of neuro-
nal injury. We have previously demonstrated that histo-
logical evidence of neuronal injury is correlated with
vestibulomotor (rotarod) and neurocognitive (Morris
water maze) performance (14). Fewer Fluoro-Jade
B positive degenerating neurons were present in the
high-dose (11 ± 1) and low-dose (15 ± 1) levetiracetam
groups versus vehicle (26 ± 2, p < 0.01) ( see Figure 2 ). In
contrast, treatment with low-dose fosphenytoin (18 mg/
kg; n = 5) did not affect histological evidence of hippo-
campal injury (28 ± 2). Furthermore, high-dose fosphe-
nytoin (54 mg/kg; n = 5) increased Fluoro-Jade B posi-
tive cells (39 ± 3). Taken together, these results suggest
that a single administration of levetiracetam following
CHI improves functional outcomes and reduces
evidence of neuronal degeneration after head injury.
This beneficial effect was not present with standard
doses of fosphenytoin, suggesting that the beneficial
effects of levetiracetam are not caused by a nonspecific
anticonvulsant effect. To the contrary, high-dose fosphe-
nytoin was associated with deleterious effects on
functional outcome and increased evidence of hippo-
Levetiracetam is Associated With Improved
Functional Outcomes and Reduction
in Vasospasm Following SAH
Routine seizure prophylaxis is also commonly em-
ployed in the setting of aneurysmal SAH. To assess
whether levetiracetam was neuroprotective in this model,
we randomized three groups of animals to receive
high-dose (54 mg/kg; n = 14) or low-dose levetiracetam
Fig. 1. (A) A single intravenous administration of high-dose leveti-
racetam improved post traumatic vestibulomotor function measured
by rotarod testing (* p < 0.05 high-dose levetiracetam versus con-
trol). Low-dose levetiracetam was not significantly different than
control. (B) Administration of fosphenytoin at a standard intrave-
nous loading dose (18 mg/kg phenytoin equivalents) did not confer
any functional benefit following closed head injury. High-dose fosphe-
nytoin (54 mg/kg phenytoin equivalents) was associated with impaired
functional performance as compare to vehicle-treated animals (* p <
0.05 versus control). All values are expressed as mean ± SD.
Levetiracetam is Neuroprotective 75
♦ Volume 5, 2006
(18 mg/kg; n = 13), or vehicle ( n = 10) following experi-
mental SAH. To recreate the clinical setting of delayed
ischemic deficit following aneurysmal SAH, drug or ve-
hicle was administered intravenously by tail vein imme-
diately following SAH, and at 12-hour intervals for the
first 3 days. Both high- and low-dose levetiracetam were
associated with functional improvements as assessed by
rotarod and neuroseverity score. This effect was sus-
tained throughout the 3-day testing period ( Figure 3 ).
Interestingly, this functional improvement was also
associated with a reduction in luminal narrowing
( Figure 4 ), suggesting that, in addition to any direct
neuroprotective effects, levetiracetam administration re-
duced vasopasm in this model.
In the current study, we demonstrate that administra-
tion of levetiracetam improves functional performance
and reduces histological evidence of neuronal injury
and vasospasm in murine models of CHI and SAH, re-
spectively. Although seizure prophylaxis has not been
shown to prevent epileptogenesis or the later develop-
ment of seizure disorder following head trauma, a num-
ber of studies have demonstrated the efficacy of this
approach in the early suppression of seizures (2) . Current
recommendations suggest the use for 1 week following
injury (1) . In the setting of aneurysmal SAH, seizures
occur with a prevalence of 4 – 10% and are more likely to
Fig. 2. (A) Representative images of Fluoro-Jade B-positive neurons in the hippocampus. Fluro-Jade B stains degenerating neurons. At 24
hours after CHI, mice treated with both high (c) and low (b) dose levetiracetam demonstrated fewer Fluoro-Jade B positive degenerating
neurons than the vehicle control (a). (B) Neuronal injury was then quantified by counting the total number of Fluoro-Jade B-positive neu-
rons present throughout the entire hippocampus, which was sampled at every eighth section (approximately 7 sections/brain). The total
number of degenerating neurons was less in animals treated with high- or low-dose levetiracetam, but greater in high-dose fosphenytoin
treated group as compared to vehicle control or low-dose fosphenytoin-treated animals (** p < 0.01 for treatment group versus vehicle).
Values = mean ± SD.
76 Wang et al.
♦ Volume 5, 2006
occur soon after the ictus (21,22) . The rapid increase in
blood pressure associated with seizures may be espe-
cially detrimental in the setting of a patient with an un-
secured aneurysm. Thus, although there is insufficient
evidence to support or dismiss the use of routine seizure
prophylaxis in SAH (23,24) , this has been incorporated
into routine practice at many institutions.
Traditionally, phenytoin is the most common AED
administered for seizure prophylaxis following brain
injury. However, phenytoin has a number of drug
interactions, requires close monitoring of drug levels,
and suspicion of adverse events such as drug fever, rash,
or thrombocytopenia often necessitates discontinuation
(3 – 5,25) . Fosphenytoin is a newer drug that is converted
to phenytoin in vivo, but is delivered in a nontoxic car-
rier solution that allows for safer intravenous adminis-
tration without significant cardiovascular side effects
(6,26) . The remaining toxicity profile is similar to phe-
nytoin. There is emerging evidence that prophylactic
treatment with phenytoin may be deleterious in patients
with acute brain injury. For example, a recent study has
demonstrated that exposure to phenytoin is associated
with impaired neurocognitive performance following
SAH (7) . These observations would be consistent with
preclinical data suggesting adverse effects of phenytoin
on recovery from acute brain injury (27) . In the current
study, we found that therapeutic doses of phenytoin ex-
erted no beneficial effect in the setting of acute brain in-
jury, and in fact high-dose phenytoin was associated
with impaired recovery.
Levetiracetam has several advantages over phenytoin
for use in seizure prophylaxis, as it is well tolerated,
does not require monitoring of levels, has minimal drug
interactions or adverse effects (28,29) , and has been re-
cently approved for intravenous administration in the
acute setting. Levetiracetam has a distinct anticonvul-
sant profile from most other classical AEDs. For exam-
ple, levetiracetam lacks activity in traditional seizure
models used to screen anticonvulsant candidates (8) .
Levetiracetam binds throughout the central nervous
system to a presynaptic vesicle protein called SV2A (30) .
The function of this protein is unknown, but it may
modulate the vesicle fusion process (31) . The binding of
levetiracetam to SV2A correlates with its anticonvulsant
effects (30) , and there is evidence that levetiracetam may
selectively interact with this integral protein under
pathophysiological conditions such as may occur with
acute brain injury or seizure activity. Levetiracetam may
Fig. 3. (A) Animals treated with either high- or low-dose levetirace-
tam had improved rotarod performance as compared to vehicle-
treated animals after subarachnoid hemorrhage (* p < 0.05 for either
dose compared to vehicle). This effect was sustained throughout the
3-day testing period. (B) Functional improvement was also demon-
strated by serial neurological clinical assessments (* p < 0.05 in both
treated groups versus vehicle).
Fig. 4. Vasospasm, defined as the reduction of MCA diameter, was
attenuated in the groups treated with both high- and low-dose leve-
tiracetam (** p < 0.01 versus vehicle).
Levetiracetam is Neuroprotective 77
♦ Volume 5, 2006
also have neuroprotective properties, and has been
shown to reduce infarct volume in a rodent model of
focal ischemia (12) . In the current study, high-dose
levetiracetam also improved functional outcomes and
reduced histological evidence of neuronal injury
following CHI. This is unlikely to be the result of its an-
ticonvulsant properties, as only a single dose given 30
minutes following brain trauma was efficacious, whereas
treatment with fosphenytoin had no comparable effect.
Our observation that supratherapeutic doses of phenyt-
oin were associated with impaired outcome is consistent
with a recent clinical study demonstrating adverse ef-
fects of phenytoin in patients with SAH (7) .
In the current study, we also observed that levetirace-
tam improves functional recovery in a murine SAH
model. Although this might have been partly because of
a direct neuroprotective effect against cerebral ischemia,
there was also a direct reduction in vasospasm, defined
by measurement of MCA luminal diameter. Although
this has never been described before, it is possible that
these affects are mediated by nitric oxide (NO). Vascular
endothelium smooth muscle tone is mediated by a bal-
ance of NO (32) and endothelial-derived constriction
factors (33) . NO depletion is associated with SAH, and
NO replacement reverses cerebral vasospasm (34 – 36) .
Interestingly, administration of levetiracetam has been
demonstrated to upregulate astrocytic production of in-
ducible NO synthase in a concentration-dependent fash-
ion (37) . In a recent study utilizing in vivo microdialysis,
levetiracetam, in a dose-dependent fashion, directly
upregulated NO production in the cerebellar nuclei of
rats (38) . Thus, it is plausible the palliative effects of
levetiracetam on reducing vasospasm and improving
functional recovery following SAH may be mediated by
its upregulation of NO synthesis. In summary, leveti-
racetam was well tolerated in two murine models of
acute brain injury. A single intravenous administration
improved functional and histological endpoints follow-
ing CHI, an effect that was not replicated with fosphe-
nytoin. Following experimentally induced SAH, admin-
istration of levetiracetam was associated with both
functional improvement and reduction in vasospasm as
compared to vehicle-treated controls. These results may
have implications for the use of levetiracetam for sei-
zure prophylaxis in the neurocritical care setting.
In summary, we demonstrate that levetiracetam is
well tolerated in two murine models of acute brain in-
jury. The beneficial effects of a single intravenous
administration of levetiracetam on functional and
histological outcomes post head injury was not repli-
cated with fosphenytoin. Following experimentally in-
duced SAH, administration of levetiracetam was associ-
ated with both functional improvement and reduction
in vasospasm as compared to vehicle-treated animals.
These results may have implications for the use of leve-
tiracetam for seizure prophylaxis in the neurocritical
care setting. The apparent neuroprotective and anti-
vasospastic effect of levetiracetam in this murine model
warrants future confirmatory trials in other animal and/
or human trials.
This work was supported by the Institute for the
Study of Aging. Junling Gao was partly supported by
Natural Science Foundation of Hebei Province, China
(grant 301404). Dr. Laskowitz is a consultant for UCB
Pharma, which provided levetiracetam. We would like
to thank Dr. Heather Vita for her thoughtful review of
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