Serum cross-reactive thymosin alpha 1 levels in rats during induction of mammary carcinoma with 7,12-dimethylbenz[a]anthracene: short- and long-term effects.

The levels of serum cross-reactive thymosin alpha 1 (CRT alpha 1) were measured at various time intervals during the course of development of mammary tumors in female Sprague-Dawley rats intubated with 7,12-dimethylbenz[a]-anthracene (DMBA; 10 mg/rat). Matched control rats were also tested simultaneously. An increase in CRT alpha 1 in DMBA-treated animals was observed within 2 h of DMBA treatment. Thereafter the levels of CRT alpha 1 in the serum of the DMBA-treated rats remained elevated for another 3 weeks prior to declining to control levels. Levels remained stationary until an increase in serum CRT alpha 1 was observed at 9-11 weeks post-DMBA treatment. This correlated with the time when mammary tumors were either palpable or observed. Levels of CRT alpha 1 fell at 13 weeks but remained slightly elevated until sacrifice due to tumor burden at 18 weeks.