Bacto-
phytohemagglutinin-P (
PHA-P) was administered in form of a single intralumbar injection of 2 mg/100 g
body weight dose to 24- to 28-mth-old female CGY rats. The accuracy of the injection technique was checked by adding 2%
lidocaine to the injection mixture, which resulted in a transient and symmetric
paralysis of the posterior limbs when reaching the cerebrospinal fluid. The total
RNA content of the liver and brain cortex were measured, and phenolic extraction of
RNA was performed the brain cortex.
Poly(A) +RNA (
mRNA) was separated from the total
RNA of the brain cortex by
oligo(dT)-cellulose chromatography. Pulse labeling with tritiated
uridine was performed 45 min before killing the animals and the incorporation of the radiolabel was measured in the respective
RNA classes and corrected for the
nucleotide pool size. The rates of total and
mRNA synthesis are expressed in percentages of the young untreated rats and compared to old untreated animals. The effects of
PHA-P was studied at 4, 10, 20 and 44 h after its injection. A considerable increase of the total
RNA content of the brain cortex was measured during the first 10 h of the experiment followed by a slow decrease. However, the
RNA content of the brain cortex was still significantly higher at the end of experiment compared to untreated old rats. The rate of total
RNA synthesis increased significantly during the first 10 h and remained constantly high until 44 h. The rate of
mRNA synthesis increased to a higher extent than that of the total
RNA, and also remained high until 44 h.