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Fig. 26.3
Fold changes in DBH, TH, and TPH mRNA expressions in mice's cerebellum exposed
to 4 ppm arsenic or 4 ppm arsenic and 150 mg/kg taurine for 60 days. The number for each experi-
ment was 6.
T
is short for taurine. Data are presented as mean ± SD. Different from control group,
a
P
< 0.05,
aa
P
< 0.01; Different from 4 ppm group,
b
P
< 0.05,
bb
P
< 0.01
signaling, and specially neurotransmission (Iio et al.
2012
; Junyent et al.
2009
;
Ozan et al.
2012
; Pan et al.
2010
). It was reported that the deficient in behavior
induced by As might be closely related to the disordered concentration of NE, DA,
and 5-HT in the central nervous system (Delgado et al.
2000
) . Whether the applica-
tion of taurine could also alleviate the disturbed concentration of NE, DA, and 5-HT
induced by As, and the potential mechanism for taurine intervening the concentra-
tion of NE, DA, and 5-HT induced by As are still unknown.
The results in the present study showed that the concentration of NE, DA, and
5-HT in the cerebellum exposed to As and taurine were significantly increased,
compared with that in the brains exposed to As alone. The similar results could also
be found in the cerebrum of mice coadministered As with taurine subchronically,
except that the tendency for the increased concentration of 5-HT wasn't significant.
Neurotransmitters are mainly stored in the synaptic vesicles, and the ultrastructure
change of synapse was also observed in the present study. The results showed that
the number of synaptic vesicles was also increased in the brains exposed to As and
taurine together. These results indicated that taurine also had a protective effect on
the decreased concentration of NE, DA, and 5-HT in the brains induced by As.
It was reported that treatment of realgar, the main element is As, could decrease the
amino acid neurotransmitters in the brains of rats, whereas the concentration of
taurine wasn't affected (Huo et al.
2012
). And extracellular taurine addition could
activate the glycine receptor and the specific taurine transporter, increase the efflux
of DA, following the release of other neurotransmitters in the central nervous sys-
tem (Chepkova et al.
2002
; Chepkova et al.
2005
). These might be the reasons that
taurine had a protective effect on the As induced the decreased concentration of
neurotransmitters in the brains in the present study.
It was reported that dopamine beta hydroxylase (DBH), tyrosine hydroxylase
(TH), and tryptophan hydroxylase (TPH) are the rate-limiting enzymes for the
synthesis of NE, DA, and 5-HT, respectively (Szot et al.
1996
). In order to further
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