Biology Reference
In-Depth Information
a
b
a
50
a
NP
NPT
LP
LPT
200
40
b
150
b
30
100
20
50
10
0
NP
NPT
LP
LPT
0
2
4
6
8
10
12
Weeks
Fig. 14.1
(
a
) Body weight and (
b
) area under growth curve (AUC) of NP, NPT, LP, and LPT mice.
Values are mean ± SEM (
n
= 8); different letters over bars indicate statistical difference;
P
< 0.05
(two-way ANOVA, Newman-Keuls post hoc test)
14.3.2
Plasma Insulin and Insulin Secretion
Fed plasma insulin levels were reduced in LP mice compared with NP (
P
< 0.05,
Fig.
14.2a
). TAU supplementation had no effect on this parameter.
Insulin release by isolated islets from LP mice was reduced at all stimulatory
glucose concentrations (11.1-22.2 mmol/L) when compared to NP group (Fig.
14.2b
,
P
< 0.05). TAU supplementation increased insulin secretion in NPT islets in the
presence of 16.7 and 22.2 mmol/L glucose (
P
< 0.03) and at all glucose concentra-
tions LPT islets showed a similar insulin secretion to that observed of NP islets
(Fig.
14.2b
).
14.3.3
ER Stress Marker Protein Expression
Isolated islets from LP mice showed a similar expression of ER stress markers com-
pared with NP (Fig.
14.3
). TAU supplementation significantly reduced CHOP pro-
tein expression in both NPT and LPT islets compared with NP (
P
< 0.05 and
P
< 0.01,
respectively, Fig.
14.3a
) and lowered islet ATF4 protein content only in NPT group
(
P
< 0.05, Fig.
14.3b
). PERK phosphorylation (p-PERK) and BIP expression were
not altered between groups (Fig.
14.3c, d
). The phosphorylated form of the pro-
survival protein Akt (p-Akt) was increased in NPT compared with NP islets
(
P
< 0.05; Fig.
14.3e
). Also, NP pancreatic islets incubated with 3 mmol/L TAU pre-
sented higher ERK1/2 phosphorylation (p-ERK1/2) after 90 s (
P
< 0.001) and
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