Comparison of expression of apoptosis regulatory proteins in the adipose tissue of tumor-bearing and diet-restricted rabbits.

Abstract

We investigated the expression of apoptosis regulatory proteins in the adipose tissue of tumor-bearing and diet-restricted rabbits, and analyzed the differences between the two groups. The apoptotic index in the tumor-bearing group was 25.1+/-12.4 on day 10 and increased to 27.2+/-14.4 by day 20. Thereafter, however, it gradually decreased, falling to 11.2+/-7.8 on day 30 and 0.67+/-0.88 on day 40. By contrast, no apoptotic cells were detected in the diet-restricted group at any of the times examined. Bcl-2 immunoreactivity was either not detected at all, or was only weakly observed in both groups. Bax expression, on the other hand, gradually increased after implantation in the tumor-bearing group. In 2 of the 5 tumor-bearing rabbits, Bax expression in adipocytes was moderate 10 days after tumor implantation, and strong by day 20, but steadily decreased thereafter. By contrast, hardly any Bax-immunopositive cells were detected in the diet-restricted group. These results suggested that loss of body weight in the tumor-bearing group was different from that in the diet-restricted group, and that it was related to adipocyte apoptosis.