Serum Amyloid P-Component (SAP) Regulation by Sex-Steroids in Rats: Compared with C-Reactive Protein (CRP)

Abstract

In order to investigate the effects of sex-steroids on SAP level in rats, SAP was purified from Wistar rats by affinity chromatography of phosphorylcholine. Sample sera were obtained from 180 young and old rats, after which, rats were injected with either estradiol (E2), testosterone (T), or dehydroepiandrosterone (DHA). Sera were serially obtained from the tail vessels until the 8th day after injection. The SAP level was assayed by micro single radial immunodiffusion. As the rats aged, the SAP levels increased from 2.9 mg/dl at 11 weeks to 10.7 mg/dl at 58 weeks. In 37-week-old rats, the SAP levels in females (6.3 ± 1.8mg/dl) were significantly (p > 0.001) higher than those in males (3.9 ± l.Omg/dl), whereas the CRP levels in females (49.8 mg/dl) were lower than those in males (61.5 mg/dl). The SAP levels did not change after T administration, but decreased significantly (p>0.001) to 70% of the prelevel after DHA injection. The SAP levels increased rapidly by E2 administration, especially in young male rats (increased to 189%). Serum E2 levels in young (llwk) male rats were very low before E2 injection, and steeply rose on the 2nd day. From these findings, the different SAP levels in mature female and male rats are attributed to E2.