Background:

Elevated serum-free fatty acid (FFA) levels induce insulin resistance (IR) or a protective mechanism to IR development in humans; it depends on FFA type.

Objetive:

This study explores the effects of oleic (OLA – unsatured) and palmitic (PAM – saturated) fatty acids on insulin action in mature adipocytes effect. Methods: Cells were incubated 18 h with or without OLA and PAM at 250 μM, and 500 μM. After the culture period, were measured: adipocyte viability, size, fatty acids mobilisation, insulin signalling proteins, and glucose uptake.

Results:

Adipocytes exhibited optimal viability tolerances regardless of the kinds of fatty acids used for treatment. However, adipocytes were hypertrophic after OLA and PAM stimuli. Additionally, lipogenesis (lipid synthesis), and lipolysis (lipid breakdown) were significantly increased by treatment with OLA, or PAM (500 μM) compared to control. Moreover, OLA results showed that there was no significant reduction in signalling cascades, except for a downstream proinflammatory response. Instead, PAM hypertrophic adipocytes were insulin resistant with alteration of proinflammatory and stress markers.

Conclusions:

Current findings suggest that PAM induces insulin resistance, mitochondrial and reticulum stress on fat cells compared to those treated with OLA that, protects adipocytes to all those alterations.