Abstract
The in vitro metabolism of tissue slices from 22 day pregnant, surgically thyroidectomized
rats was studied. The fetuses of these animals have been shown previously to have
depressed serum glucose, serum protein and liver protein and glycogen levels.
The maternal livers of the hypothyroid animals show an in vitro metabolism typical
of hypothyroidism. However, the fetal livers are very different from the maternal
livers in their glucose utilization. The livers of these fetuses of hypothyroid mothers
show greater in vitro uptake and utilization of glucose than the fetuses of controls.
The fetal liver fractional distribution of this glucose among the four compartments
measured - CO2, glycogen, protein and lipid - is not significantly altered by the treatment. The
failure of these fetuses to accumulate liver glycogen normally is obviously not due
to an inability to synthesize glycogen but rather is due to higher glycogen turnover
and possibly insufficient or inappropriate substrate levels. These fetuses have the
capacity for lipid and protein synthesis from glucose and the in vitro incorporation
into these components is greater than normal. The in vitro liver metabolism in the
fetuses of hypothyroid mothers is not indicative of fetal hypothyroidism and, in fact,
suggests fetal hyperthyroidism at this period of gestation.
Key words
Glucose Metabolism - Hypothyroid - Hyperthyroid - Fetal - Placental - Maternal
1 Supported by Biomedical Sciences Support Grant, DHEW-5505-R07024-9.
