CHUNG, SOONKYU, Ph. D. Mechanisms by Which Conjugated ...

Anti-adipogenic Mechanisms of CLA
The evidence cited above has led researchers to appreciate that trans-10 cis-12 CLA
decreases adipogenesis in adipocytes from both rodents and humans. However, the
underlying mechanism by which trans-10, cis-12 CLA causes delipidation is conflicting,
depending on cell type, metabolic status, and species. Several different mechanisms have
been proposed for the anti-adipogenic mechanism of CLA supplementation.
The simplest explanation is that CLA induces a decrease in food intake. Several in
vivo animal studies have reported that CLA feeding attenuates abdominal fat deposition
coupled with reduced food or energy intake in mice and rats (Park et al. 1999; West et al.
1998; DeLany et al. 1999). However, a decrease in food intake seems to be marginal and
cannot fully account for the marked reduction in fat deposition. It might be associated
with inappropriate preparation of CLA supplementation (e.g. unpleasant smell of CLA)
rather than increasing lipolysis, because reduced food intake is seldom reported in well
controlled vehicle studies (Ostrowska et al. 1999; Yamasaki et al. 2003) or in human
trials (Riserus et al. 2004, 2004).
One of the proposed mechanisms is that trans-10, cis-12 CLA inhibits the activities
of lipid metabolism regulating enzymes and gene expression, such as lipoprotein lipase
(LPL) and stearoyl-CoA desaturase (SCD-1). It has been proposed that CLA’s inhibition
of LPL activity is the key mechanism causing delipidation, i.e., reducing lipid uptake into
adipocytes (Park et al. 1999). Alternatively, SCD-1, an enzyme responsible for
introduction of cis-double bond at the C9 position of fatty acyl-CoA, has been proposed
by Natambi’s group as the target of trans-10, cis-12 CLA. CLA mediated inhibition of
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