Proteins of rat serum: III. Gender-related differences in protein concentration under baseline conditions and upon experimental inflammation as evaluated by two-dimensional electrophoresis

We have previously described the major components of rat serum (Electrophor esis 1998, 19, 1484-1492 and 1493-1500). In this report we examine sex-rela ted differences in protein concentrations, both in control animals and upon experimentally induced inflammation. Under baseline conditions approximate ly one third of the spots resolved in serum by two-dimensional electrophore sis (2-DE) are expressed at levels greater than or equal to 25% higher in f emale rats than in male rats and a further 10% at levels greater than or eq ual to 25% lower. Inflammation increases the expression of the positive acu te-phase reactants: hemopexin, ceruloplasmin, al-antitrypsin (all approxima tely 2-fold), C-reactive protein (3- to 5-fold), serine protease inhibitor- 3 (4- to 5-fold), thiostatin (> 5-fold in females, > 20-fold in males), clu sterin, orosomucoid, haptoglobin chains and alpha(2)-macroglobulin. The bas eline level of the last four markers is below the detection limit, hence no percent increase can be computed. Conversely, negative acute-phase reactan ts are reduced on inflammation: alpha(1)-inhibitor III, alpha(2)-HS-glycopr otein, kallikrein-binding protein and transthyretin (all reduced to between 1/2 to 1/3 of the baseline levels), retinol-binding protein (to about 1/2 to 1/4) and albumin (to 2/3). Except for thiostatin, the changes in acute-p hase protein levels are similar in male and female rats.*