C-reactive protein in rat: in development, pregnancy and effect of sex hormones.

1. In Wistar strain rats, the serum concentration of C-reactive protein (CRP) was 3.6 +/- 0.8 micrograms/ml at the birth and no apparent change was observed during 15 days after delivery. 2. Thereafter it increased about 30 times rapidly until day 30 and then rather gradually reaching the adult level of 0.4-0.8 mg/ml. 3. Before delivery, there were two peaks in the CRP level, on day 0 and day 15 of gestation. The concentrations were 0.70 +/- 0.06 and 0.77 +/- 0.10 mg/ml, respectively. 4. The CRP level decreased to 0.42 +/- 0.05 mg/ml at the delivery and increased to 0.54 +/- 0.05 mg/ml within 2 days after delivery. 5. The treatment with estradiol-17 beta resulted in the decrease of CRP (52%) in both ovariectomized and non-treated female rats. 6. The treatment with testosterone resulted in the increase of CRP in male but not in female rats. 7. However, in ovariectomized rats, testosterone elevated the serum CRP. 8. In neither ovariectomized nor intact female rats, progesterone and corticosterone showed any remarkable effect.