Table 3.
Effects of leptin treatment in vivo on the activities of glycogen synthase, glycogen phosphorylase, and ACC in ob/ob mouse liver
| Enzyme | Control, units/glww | Leptin, units/glww | |
|---|---|---|---|
| GSa | 0.19 ± 0.05 (7) | 0.58 ± 0.11 (8) | P = 0.01 |
| GST | 0.62 ± 0.10 (7) | 1.15 ± 0.18 (8) | P < 0.05 |
| GSa/GST | 0.30 ± 0.05 (7) | 0.50 ± 0.05 (8) | P < 0.05 |
| GPa* | 12.5 ± 2.0 (7) | 11.3 ± 1.5 (8) | NS |
| ACC(−cit)† | 0.37 ± 0.02 (8) | 0.27 ± 0.04 (8) | P < 0.05 |
| ACC(+cit)† | 0.72 ± 0.03 (8) | 0.51 ± 0.05 (8) | P < 0.005 |
| ACC(−/+)† | 0.52 ± 0.02 (8) | 0.53 ± 0.02 (8) | NS |
| FAS‡ | 0.52 ± 0.04 (10) | 0.29 ± 0.03 (10) | P < 0.001 |
Leptin treatment as given in Table 1. Units/glww is defined as the conversion of 1 μmol of substrate per min at 30°C per glww. Number of experiments is in parentheses. GPa, the a-form of glycogen phosphorylase. NS, not significant.
*
For comparison, GPa for lean mouse liver (N = 4) was 7.2 ± 4.2 units/glww.
†
ACC activity was measured in the absence (−cit) or presence (+cit) of 4 mM citrate. ACC(−/+) is the ratio of activity at 0 and 4 mM citrate.
‡
For FAS activity is defined as the synthesis of 1 nmol of palmitic acid per min at 30°C per mg of liver protein.