Analysis of the Expression of Growth Factor, Interleukin-1, and Lactoferrin Genes and the Distribution of Inflammatory Leukocytes in the Preimplantation Mouse Oviduct1

Abstract

The oviduct provides the environment in which fertilization of the egg and subsequent development of the preimplantation mouse embryo occurs, but little is known about the oviduct's capacity to produce growth factors or cytokines that may influence these preimplantation events. Northern blot analysis and/or immunohistochemistry were employed to examine the expression or cellular distribution, respectively, of the growth factors heparin-binding epidermal-like growth factor (HB-EGF), transforming growth factor (TGF) alpha, epidermal growth factor (EGF), insulin-like growth factor-I (IGF-I), TGF beta 1, TGF beta 2, and TGF beta 3; of estrogen-regulated lactoferrin (LF); and of the cytokines interleukin (IL)-1 alpha and IL-1 beta in the mouse oviduct during the preimplantation period (Days 1-4 [Day 1 = vaginal plug]) and 7 days after ovariectomy. The results demonstrated that, except for EGF, each of the growth factors and the LF genes are expressed in the ampulla and isthmus regions of the oviduct throughout the preimplantation period. Prominent immunostaining in secretory epithelial cells was noted for HB-EGF, TGF alpha, IGF-I, TGF beta 1, and TGF beta 2, and LF. Less intense immunostaining in the serosa and/or smooth muscle was also noted for TGF alpha, IGF-I, and TGF beta 1. In contrast, intense immunostaining in smooth muscle was noted for TGF beta 2, and TGF beta 3 was detected exclusively in smooth muscle cells. The abundance of these mRNAs was relatively constant during the preimplantation period, and ovariectomy did not reduce the levels of these mRNAs. In contrast to these growth factors, the cytokine mRNAs examined (IL-1 alpha and IL-1 beta) were at or below the limits of detection under these experimental conditions, and inflammatory leukocytes (LF-immunopositive neutrophils, IL-1 beta-immunopositive monocytes/macrophages, or peroxidase-positive eosinophils) were not detected in the oviduct, but were abundant in the adjacent uterine stroma on Day 1. These studies show that several growth factors are synthesized by the mouse oviduct and suggest that ovarian steroids do not play a major role in modulating expression of these genes in the oviduct during the preimplantation period. Furthermore, unlike the uterus on Day 1, the oviduct does not exhibit an inflammatory response to mating.