Society of Toxicology Abstract
41st Annual Meeting & ToxExpo™
Nashville
March 17-21, 2002
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Volume 66, Number1-S |
March 19, 2002
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921
MECHANISM OF APPETITE SUPPRESSION
BY A NOVEL, NATURAL HYDROXYCITRIC ACID
S.E. Ohia, C.A. Perre, A.M. LeDay, M. Bagchi and D. Bagchi
School of Pharmacy & Allied Health Professions, Creighton
University, Omaha, NE.
Although evidence available indicates that Garcinia cambogia-derived
natural extract,
(-)-hydroxycitric acid (HCA, Super Citrimax®) is a potent appetite
suppressant and an inhibitor of body fat biosynthesis, its exact
mechanism of action is yet to be fully elucidated.
In a previous
study, we showed that in the rat brain cortex, HCA can increase
the release/availability of radiolabeled 5-HT ([3H]-5-HT),
a neurotransmitter implicated in the regulation of eating behavior
(Ohia et al., FASEB J. 15: Abs. No 207.13, 2001).
The aim of
the
present study was two-fold: (a) to evaluate the safety of HCA
in vivo and (b) to determine the effect of HCA on 5-HT uptake
in rat
brain cortex in vitro.
In safety studies, acute oral toxicity,
dermal toxicity, dermal irritation and eye irritation, were
conducted in animals with different doses of HCA yielding
an LD50 greater than 5000mg/kg following oral administration
of
this
compound.
Isolated rat brain cortex slices were incubated
in oxygenated Krebs solution for 20 minutes and then transferred
to
buffer solutions containing [3H]-5-HT for different
time intervals.
In some experiments, tissues were exposed
to HCA
(10 uM -1 uM), fluoxetine (100 uM) and clomipramine (10
uM ). Uptake of [3H]-5-HT was expressed as
d.p.m./mg wet weight.
A time dependent uptake of [3H]-5-HT
occurred in cortical slices reaching a maximum at 60
mins. HCA (300 uM)
caused a 20% decrease whereas fluoxetine and/or clomipramine
inhibited the time-dependent uptake of [3H]-5-HT.
At 90 min HCA (300 uM) caused a 20% decrease whereas
fluoxetine plus
clomipramine inhibited [3H]-5-HT uptake
by 30%.
We conclude that HCA is a safe compound that
can
inhibit
[3H]-5-HT
uptake (and increase 5-HT availability) in isolated
rat brain cortical slices in a manner similar to
that of
selective serotonin reuptake inhibitors (SSRIs).
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