Acute-phase response of plasma protein synthesis during experimental inflammation in neonatal rats.

The pattern of plasma protein concentrations in neonatal rats differs characteristically from that in adult animals. Immediately after birth, the concentration of alpha 2-macroglobulin is about 200 times higher, that of major acute-phase alpha 1-protein the same, and that of alpha 1-acid glycoprotein, another acute phase protein, is considerably lower, compared with the values observed in healthy adults. The concentration of prealbumin, a negative acute-phase protein, remains low in the immediate postnatal period, but increases at a time when concentrations of both thyroxine and corticosterone increase. At this time, there is also a distinct increase in the concentration of alpha 1-acid glycoprotein. Despite the differences in concentration of plasma proteins in the adult rat and the neonate, the neonatal liver has the capability to respond to an acute inflammation with a coordinated change in the synthesis rates of plasma proteins similar to that observed in adult animals.