Abstract

Previous in situ hybridisation studies from our laboratory have shown that expression of certain milk protein genes is very high in some areas of the mammary glands of sheep and cattle, while in other areas containing an abundance of fat globules, it is virtually zero. We wished to determine if this heterogeneity was due to local variations in the concentrations of lactogenic hormones and/or their receptors. Artificially increasing the local concentration of lactogenic hormones in the sheep udder was attempted by inserting time release capsules containing prolactin, hydrocortisone and insulin directly into the gland up to one week before sacrifice. The local concentration of prolactin, and the milk gene expression relative to controls, appeared unchanged by the implants. The immunoreactivity of prolactin and its receptor in the mammary epithelial cell cytoplasm and in particular, the nuclei, were demonstrated and appeared to vary with the secretory activity of the cell.

I, Valentine, EM Hurley, and W Glass

Proceedings of the New Zealand Society of Animal Production, Volume 53, , 111-114, 1993