THE EFFECTS OF ESTROGEN AND PROGESTERONE ON INSULIN SENSITIVITY IN FEMALE RATS

The effects of 17-beta-oestradiol (E2) and progesterone (P) on insulin sensitivity were determined in oophorectomized (OVX) rats by the eugl ycaemic hyperinsulinaemic clamp technique combined with measurements o f insulin-stimulated 2-deoxy-D-glucose (2-DOG) transport and glycogen synthesis in white and red parts of the gastrocnemius, the extensor di gitorum longus and soleus muscles as well as in the liver (only glycog en synthesis). OVX was followed by insulin resistance in the clamp mea surements. This was paralleled by a decreased insulin-stimulated conte nt of 2-DOG in muscles, an index of glucose transport. Glycogen synthe sis in muscle was also decreased, although to less extent. E2, alone o r in combination with P, restored this to values of intact controls, w hile P alone was followed by insulin resistance. Liver glycogen synthe sis was also decreased by OVX but this required combination of E2 and P to be fully restored. It was concluded that particularly E2 plays an important role in the maintenance of normal insulin sensitivity while P alone seems to be followed by insulin resistance, both effects appa rently mainly by regulation of glucose uptake in muscle. E2 + P may be of importance for maintenance of normal glycogen synthesis in the liv er.