The atherogenic index, a ratio of VLDL + LDLcholesterol
to HDL-cholesterol, decreased transiently in
CLA group at 30 day owing to rise in HDL-cholesterol;
however, there was no significant difference among three
dietary groups (Fig. 1).
Deposition of fat in liver was increased by 47.2 % and
42.5 % on CLA and CLA + SMP diets, respectively, when
compared with control diet fed mice. The deposition of
cholesterol in liver was significantly greater in CLA
(0.8 mg/g tissue ± 0.10) and CLA + SMP (0.9 mg/g tissue ±
0.10) groups than in control (0.5 mg/g tissue ± 0.06) group,
the difference between CLA and CLA + SMP groups was
statistically not significant. TAG content was also greater on
CLA (2.4 mg/g tissue ± 0.26) and CLA + SMP (2.1 mg/g
tissue ± 0.18) diets than on control (1.4 mg/g tissue ± 0.21)
diet. The proportion of cholesterol and TAG in liver fat was,
however, similar in three dietary groups. The increase in
liver cholesterol and TAG content, thus, could be due to an
increased fat accumulation in liver of the two groups which
may in turn be the result of decreased β-oxidation in CLA
and CLA + SMP groups as compared to the control group
(data published) (Sagwal and Kansal 2010). Takahashi et al.
(2003) also reported similar observation with a 10-fold
increase in the liver TAG content in mice fed linoleic acid.
Wilson et al. (2006) observed that t10, c12 isomer of CLA is
effective in reducing blood cholesterol levels but not aortic
cholesterol accumulation in hamsters. Our study showed
that non-fat milk is effective in averting the CLA induced
increase in blood cholesterol, but the fat accumulation in
liver could not be prevented. One of the mechanisms behind
an increase in liver lipids may involve the reduction of leptinand adiponectin mRNA by t10, c12-CLA (Warren et al.
2003). Also, the accumulation of fat in liver may be due to
the hyperinsulinemia caused by CLA (Clément et al. 2002)
which SMP could not prevent as milk proteins are also
insulinotropic (Nilsson et al. 2004). Insulin activates fatty
acid uptake in the liver possibly causing high fat deposition
in liver of CLA and CLA + SMP groups.