The Toxicologist - Society of Toxicology

nology to develop improved methods. They agreed that vaccines that use the largest
number of animals and that are associated with the greatest pain and distress should
be the highest priority for development and validation of alternative methods. High
priorities included implementation and further optimization/development activities
for alternative methods for rabies and Clostridial vaccines. Participants also emphasized
the need to find ways to avoid or minimize challenge testing with live
viruses and bacteria that are hazards to laboratory workers or the environment.
Ways to promote the increased use of accepted methods were also discussed.
Implementation of the workshop recommendations is expected to advance the use
and availability of alternative methods for vaccine potency and safety testing while
ensuring continued protection of human and animal health. ILS Staff supported by
NIEHS contract N01-ES-35504.
2582 ENERGY BALANCE IN MICE CONSUMING A HIGH
FAT DIET AND WHEY PROTEIN.
H. G. Shertzer 1 , S. E. Woods 1 , M. Krishan 1 ,M. Genter 1 and K. J. Pearson 2 .
1 Environmental Health, University of Cincinnati Medical Center, Cincinnati, OH
and 2 Graduate Center for Nutritional Sciences, University of Kentucky, Lexington, KY.
In mice and humans, a high fat (HF) diet results in excessive weight gain, adiposity
and secondary metabolic complications associated with increased risk for fatty liver
disease and type 2 diabetes. Protein rich diets may improve various aspects of HF
diet-mediated metabolic disorders. The objective of this study was to evaluate the
influence of whey protein isolate (WPI) on metabolic changes in mice fed a HF
diet, in the context of systemic energy balance. C57BL/6J mice received either a
normal diet or a HF diet for 11 weeks. A subgroup of mice consuming HF diet was
administered 0.1 g WPI/ml drinking water. WPI diminished the HF diet-induced
increases in body weight and percent body fat, although caloric consumption was
constant in all groups. These results could be explained by the finding that HF diet
decreased basal metabolic rate, respiratory quotient, and hepatic mitochondrial respiration,
effects prevented by WPI. Furthermore, WPI restored the diminished intake
of protein that occurs with the HF diet, and reduced fat and carbohydrate consumption
commensurate with the increase in protein. Health implications for WPI
in association with a HF diet were reflected in early biomarkers for fatty liver disease
and type 2 diabetes. We found that WPI diminished HF diet-associated fatty
liver, by reducing the number of hepatic lipid droplets and deposition of nonpolar
lipids by 43% and 76%, respectively. Furthermore, WPI improved glucose tolerance
and prevented the increase in insulin resistance in mice fed the HF diet. We
conclude that in mice receiving a HF diet, consumption of WPI increases basal
metabolic rate and blocks the metabolism of dietary lipid. Since WPI ameliorates
the deleterious effects of HF diet-mediated hepatosteatosis and insulin resistance,
WPI dietary supplements may intervene in the early stages of developing fatty liver
disease and type 2 diabetes. (NIEHS Center for Environmental Genetics P30
ES06096)
2583 A COMPARATIVE STUDY OF NICOTINAMIDE AND
TAURINE FOR ANTI-DIABETIC AND ANTIOXIDANT
ACTIONS IN STREPTOZOTOCIN-INDUCED DIABETES
IN RATS.
K. G. Pandya and C. A. Lau-Cam. St. John’s University, Jamaica, NY.
Nicotinamide (NIC) and taurine (TAU) are two natural compounds possessing biological
properties relevant to diabetes mellitus (DM). While NIC has shown potential
for preventing the development of DM, TAU has demonstrated insulin-like
effects and antioxidant and hypolipidemic actions. On these premises, the present
study was designed to compare NIC and TAU for the ability to protect against typical
DM-induced biochemical alterations in an animal model. For this purpose,
Sprague Dawley rats (225-250 g) were treated with an oral dose of either NIC or
TAU (2.4 mM/kg in citrate buffer pH 4.5), followed 45 min later by an intraperitoneal
dose of streptozotocin (STZ) (60 mg/kg in citrate buffer pH 4.5).
Treatments with NIC or TAU were continued after 1 day and for another 54 days.
Control animals received only citrate buffer pH 4.5 each day. On day 57 of the
study, the animals were decapitated to obtain blood samples, which were processed
for plasma, and the plasma fractions analyzed for glucose, insulin, cholesterol,
triglycerides, malondialdehyde, nitric oxide, reduced glutathione, glutathione
disulfide, catalase, glutathione peroxidase and superoxide dismutase. STZ-induced
DM resulted in marked increases (ranging from 64-330% over control values) in
all parameters but reduced glutathione and antioxidant enzyme activities, which
were reduced (by 49-65% of control values). A pretreatment and post treatment
with either NIC or TAU led to a significant attenuation of the altering effects of
DM, with potency differences between these two compounds not exceeding 10%
of each other. The only exceptions were the effects on plasma lipids, for which NIC
was inactive, and the plasma NO, for which TAU was more potent than NIC. The
present results indicate that while NIC and TAU can provide equipotent protec-
tion against the development of DM and its biochemical consequences, NIC is less
appropriate because of a lack of hypolipidemic effect and a weaker action on NO
depletion.
2584 COMPARISON OF THE EFFECTS OF NICOTINAMIDE
AND TAURINE IN THE BRAIN AND SPINAL CORD
AGAINST OXIDATIVE STRESS BY STREPTOZOTOCIN-
INDUCED DIABETES IN RATS.
S. N. Patel and C. A. Lau-Cam. St. John’s University, Jamaica, NY.
Diabetes fosters a state of oxidative stress manifested by lipid peroxidation, free radical
production and the loss of antioxidant defenses. Nicotinamide (NIC) and taurine
(TAU) are two natural compounds which, in this laboratory, have shown the
ability to attenuate oxidative stress in the central nervous system of rats when
acutely administered before a diabetogen such as streptozotocin (STZ). The present
study was undertaken to specifically determine the effect of a long term treatment
with either NIC or TAU on diabetes-induced oxidative stress in the brain and
spinal cord and the extent of such an effect in various brain areas. In the study,
Sprague-Dawley rats (225-250 g) were treated with an oral dose of NIC or TAU
(2.4 mM/kg) in citrate buffer pH 4.5, followed 45 min later by an intraperitoneal
dose of STZ (60 mg/kg in citrate buffer pH 4.5). A treatment with NIC, TAU or
NIC + TAU was continued for an additional 54 days. During this time, control animals
received only citrate buffer pH 4.5 each day. On day 57, the brains were removed
following decapitation and sectioned into portions representing the brain
stem, cerebellum, cortex and spinal cord. An aliquot of each brain area was homogenized
with PBS pH 7.4 (1:30, w/v) and the supernatant isolated upon centrifugation
was used to assay malondialdehyde (MDA), nitric oxide (NO), reduced
(GSH) and oxidized (GSSG) glutathione, and the antioxidant enzymes catalase
(CAT), glutathione peroxidase (GPX) and superoxide dismutase (SOD). Relative
to control samples, diabetes induced MDA formation, which was significant only
in the spinal cord and cerebellum, and increased NO and GSSG while lowering the
GSH, GSH/GSSG ratio, and activities of antioxidant enzymes in all brain areas.
Generally, the cortex was the most affected and the brain stem the least. Although
TAU and NIC attenuated the actions of STZ-induced oxidative stress throughout,
at the present doses NIC was usually more potent than TAU, especially against
changes in the values of NO, GPX and SOD.
2585 PROTECTIVE EFFICACY OF A COMBINATION OF
HUPERZINE A STEREOISOMERS AGAINST SOMAN
EXPOSURE IN GUINEA PIGS.
Y. Wang 1 , Y. Wei 1 , S. Oguntayo 1 , N. Jensen 2 and M. P. Nambiar 1, 3 . 1 Closed
Head Injury, Walter Reed Army Institute of Research, Silver Spring, MD,
2 Collaborative Research Facility, U.S. Army Medical Research Institute of Chemical
Defense, Edgewood, MD and 3 Department of Medicine, Uniformed Services
University of the Health Sciences, Bethesda, MD.
The mechanism of neuropathology after lethal exposure to nerve agents is complex.
Optimal neuroprotection requires drugs with multiple properties to protect against
seizures, neuronal degeneration and inflammation as well as induction of neuroregeneration.
Huperzine A (Hup), a potential Alzheimer’s disease drug, has several
beneficial effects including modification of beta-amyloid peptide, reduction of oxidative
stress, anti-inflammation, anti-apoptosis and regulation of nerve growth factor.
Natural [-]-Hup is a reversible AChE inhibitor that restricts its neuroporotective
ability for treatment. [+]-Hup A, a stereoisomer, is a poor AChE inhibitor and
can be used as both pre-/post-exposure treatments. We proposed that particular
combination of [-]-Hup or [+]-Hup, with different degrees of AChE inhibition can
protect strongly by both the mechanisms of reversible AChE inhibition and neuroprotection
against nerve agents. Efficacy of [+]-Hup and [+]&[-]-Hup was evaluated
in a guinea pig model. Animals were pretreated with [+]-Hup (40mg/kg) or
pyridostigmine bromide (PB, 26μg/kg, im) and 30 min later exposed to 1.2 X
LD50 soman (GD, 33.6μg/kg, sc), and a combination of atropine (2 mg/kg, im)
and 2-PAM (25mg/kg, im) 1 min after GD exposure. EEG and ECG were
recorded for 24 h. The survival rate for PB group, [+]-Hup group and [+]&[-]-Hup
group was 30%, 80% and 100% (n=10) respectively. Compared to PB, pretreatment
with [+]&[-]-Hup and [+]-Hup significantly inhibited epileptic EEG powers
(n=8, p