Abstract

Cytokines such as interferon-gamma (IFN-g) can stimulate the production of nitric oxide (NO) from mammary epithelial cells, which in turn may play a role in intramammary defence of the mammary gland. In this study, comparisons were made with the production of IFN-g stimulated NO from Comma-D cells (murine mammary epithelial cell line) and explants of mammary tissue collected from both pregnant (day 12-14 of gestation) and lactating (day 12-14 postpartum) rats. Response to IFN-g was measured as the production of nitrate and nitrite (NOx) in the culture medium. Comma-D cells and explants of mammary tissue from pregnant and lactating rats responded to treatment with 250 U/ml IFN-g with an increase in NOx of 5231, 300 and 373% respectively. The response to IFN-y was lower (P<0.001) in explants than in Comma-D cells. Inclusion of nitric oxide synthase (NOS) inhibitors aminoguanidine (100 mM) and Nw-nitro-L-arginine (1 mM) in the culture medium reduced NOx production by the Comma-D cells to 31 and 19% of stimulated activity respectively. This suggests that Comma-D cells are a good model for investigating effects of cytokines on mammary epithelial cell production of NO, and may also provide a useful means of screening other milk bioactives for their potential role in intramammary defence.

S-A, Turner, DDS MacKenzie, and CG Prosser

Proceedings of the New Zealand Society of Animal Production, Volume 62, Palmerston North, 3-6, 2002