Messenger RNA levels of plasma proteins following fasting

1. The effect of fasting on hepatic mRNA levels of seven plasma proteins was examined in the rat. 2. The levels of mRNA were measured directly in cytoplasmic extracts by hybridization to specific 32P-labelled cDNA probes. 3. Following a 48 h period of fasting, the mRNA levels of apolipoprotein E, apolipoprotein A-IV, albumin, transferrin, and transthyretin decreased by 15-30%, while apolipoprotein A-II decreased by 78% compared with non-fasted control rats. The mRNA for apolipoprotein A-I increased by 33%. 4. These findings suggest that mRNA levels in the liver following fasting are regulated independently and variations in these levels may be due to differences in transcription rates or mRNA stability.