Figure 4.

Skeletal muscle fibre immunohistochemical analysis of insulin resistance in rats fed a control diet (N), high-lard diet (L) or high-fish oil diet (F) Glut4: Without insulin administration, the immunostaining for Glut4 was evident in all groups of rats, although less in the L rats. After insulin administration (15 min after an i.p. injection of insulin), positivity for Glut4 in the N muscle fibres exhibited a diffuse punctuate distribution, suggesting translocation from perinuclear depots to the plasmalemma throughout the sarcoplasm. In the L muscle fibres, the positivity was primarily perinuclear (arrow), except in a few fibres in which the positivity was sarcoplasmic. In F muscle fibres, the immunostaining for Glut4 was massive in most of the fibres. InsR: N, F and L fibres exhibited positivity for InsR, whereas following insulin stimulation, the L fibres were only weakly positive, in contrast to the InsR positivity for N and F fibres.