IL-1 activity is expressed differently during pregnancy in the rat uterine artery than in aortic or uterine tissues.

Abstract

Uterine artery was shown to be unique in its capacity to change in size and function during pregnancy. As interleukin-1 (IL-1) was shown to be involved in reproduction processes, the aim of this study was to determine the levels of IL-1 activity of the uterine artery tissue in pregnant rat. Nine virgins and nine midpregnant rats were selected. Both uterine arteries were obtained, together with reference tissues from aorta and uterus. The levels of IL-I were examined in the above tissues after culturing with media alone (control; CT), and media that contained stimulants like tumor necrosis factor-alpha (TNF-a) or lipopolysaccharide (LPS). IL-1-like activity was evaluated by its capacity to promote the culture growth of 1A-5 and cytotoxic T lymphocyte derived (CTLD) cell lines. This activity was expressed as optical density (OD)/mg protein of the examined organ. Uterine artery tissue, of pregnant rats, cultured in medium alone produced significantly higher levels of IL-1 than uterine artery of virgin animals under the same conditions (16.2 S.E. 1.3 versus 0.6 S.E. 0.05 OD/mg protein, respectively; P < 0.02). Stimulation of uterine artery in vitro by LPS and TNF increased their capacity to secrete IL-1. In comparison with uterine artery, aorta produced higher levels of IL-1 in virgin rats compared with pregnant rats (13.6 S.E. 1.2 versus 1.6 S.E. 0.1; P < 0.02). Stimulation of aorta tissues (from both virgin and pregnant rats) with LPS, in vitro, significantly decreased their capacity to secrete IL-1 (P < 0.04). Stimulation of aorta tissues from virgin rats with TNF-alpha, in vitro, did not change their capacity to secrete IL-1 activity. However, stimulation of aorta tissues from pregnant rats with TNF-alpha decreased the secretion of bioactive IL-1. The levels of IL-1 produced by uterine tissues from virgin and pregnant rats were similar, and stimulation with either LPS or TNF-alpha significantly decreased their capacity to secrete IL-1 (P < 0.04). The high level of IL-1 activity detected during pregnancy in the uterine artery may suggest its unique involvement in the changes occurring throughout pregnancy in those blood vessels.