The MAPK family is a well-known group of enzymes that is
involved in the regulation of cellular survival, proliferation and death
[42,43]. The MAPK cascade includes proteins such as ERK, JNK and
p38, which have been described to be involved in the activation of ARE
[44]. Previously, we also suggested that the expression of MAPK and
Nrf2 were significantly distinct from rats with different age[31]. The
interactions of flavonoids within neuronal signaling pathways are
suggested through modulating phosphatidylinositol-3 kinase (PI3K)/
Akt, protein kinase C and other signaling cascades[45,46]. Herein we
focused on the expression of downstream signaling cascades that
modulate both antioxidant capacity and neurotransduction. In our
study we found that the hepatic levels of phospho-p38 and phosphoJNK in SAMP8 control mice were significantly (Pb.05) higher than
those in SAMR1 mice and that the administration of ME reduced the
activation of p38 and JNK (Fig. 3). Furthermore, as compared with
SAMR1 mice, lower expression of cerebral and hepatic phospho-ERK
were observed in SAMP8 control mice, and the activated ERK levels
were also increased upon dietary supplementation with ME (Fig. 4). A
previously published study showed that the relationship between
ageing and MAPK family expression was subtle and inconsistent[47].
However, in the present study, we demonstrated that up-regulation of
JNK and p38 and down-regulation of ERK might be involved in the
ageing process, and that dietary supplementation with antioxidants
such as mulberry may help modulate the expression of these signal
transduction molecules.