Does carbon dioxide therapy really diminish localized adiposities? Experimental study with rats

The probability of a positive effect of carbon dioxide (CO(2)) gas on the physiologic oxidative lipolytic process led to its use for localized adiposities. The authors considered that existing studies on CO(2) therapy were not sufficient to exhibit the efficiency of CO(2) therapy. The scientific basis for evaluating CO(2) therapy including standard dietary regimen, standard daily physical effort, and standard psychosocial stimuli was not clear. Despite this unclear situation, CO(2) therapy is extremely popular worldwide. The authors designed an experimental study using histomorphologic examination and the laser-Doppler flow meter to monitor treated tissue in rats. They devised a controlled applicator device appropriate for gas injection of rats and compared biochemical effects between CO(2) and breathable air.

In this study, 28 female Wistar rats weighing 300 g were divided into five groups: sham group, acute effect of CO(2) group, acute effect of breathable air group, chronic effect of CO(2) group, and chronic effect of breathable air group. Gas was injected into the right groin of the rats via a specially designed device.

The bulging disappeared after approximately 30 min in the CO(2) injection groups but continued for more than 48 h in breathable air injection groups. The blood flow and velocity in terms of changes in the signals observed using the laser-Doppler technique did not demonstrate a significant increase in the values of the gas injection groups compared with the sham group 1. A statistical difference in the number of adipocytes was found between the groups.

The study findings demonstrated a statistically significant decrease in adipocyte diameters during both the early and late phases of the subjects injected with CO(2). With adipocyte volume defined as an achievement, CO(2) therapy was found to be more successful than air injection. Furthermore, compared with the control group, the decrease in adipocyte volume also was statistically significant in breathable air injected groups (groups 3 and 5). This result suggests that the mechanical effects of gas injection are more important than the metabolic effects.