Maternal diabetes is associated with marked increases in insulin receptor (IR) numbers on fetal tissue plasma membranes. We examined the effects of alloxan-induced diabetes in pregnant New Zealand rabbits on IR mRNA levels in fetal rabbit liver at 31 d. gestation.
Total IR increased 4 fold in offspring of diabetics. Fetal rabbit liver Poly A+ RNA was subjected to gel electrophoresis, hydridization to a radiolabelled rat IR cDNA probe and autoradiographs analyzed by densitometry. Data were expressed as a percent of maximum intensity compared to a constitutive standard,(actin mRNA). Ratios of IR to actin mRNA were also calculated for each specimen from slot blot analyses. There was no change in IR m RNA levels in fetal liver from offspring of diabetic pregancies. CONCLUSIONS: Increases in IR number in fetal tissues of diabetic pregnancies is not due to an increase in receptor mRNA levels, but possibly may be explained by either post-transcriptional or translational changes, or by differences in membrane environment (i.e., fluidity) which alters receptor exposure.
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Biochimica et Biophysica Acta (BBA) - Molecular Cell Research (1989)