Expression and regulation of histidine decarboxylase mRNA expression in the uterus during pregnancy in the mouse

It has been hypothesized that hormonally regulated histamine production pla ys a role in preparation of the uterus for implantation. Histidine decarbox ylase (HDC) is the rate-limiting enzyme for histamine production. The curre nt study was designed to determine intrauterine expression of HDC mRNA expr ession during pregnancy in the mouse, High levels of HDC mRNA expression we re observed in the preimplantation mouse uterus with peak expression occurr ing on day 4. High levels of HDC mRNA expression were also detected in the post-implantation uterus, In an effort to determine whether HDC mRNA is reg ulated by pro-inflammatory cytokines, the HDC mRNA pattern was compared to intrauterine expression of mRNA's for interleukin-1 alpha (IL-1 alpha), IL- 1 beta, macrophage chemotactic protein-1 (MCP-1) and RANTES (regulated on a ctivation, normal T expressed and secreted) during the periimplantation per iod. IL-1 beta, MCP-1 and RANTES mRNA levels were increased in the uterus o n days 1-2 and on days 4-5. Increased expression of IL-1 alpha mRNA was obs erved on days 1-2 and days 5-7, There was no clear relationship between HDC mRNA expression and cytokine/ chemokine mRNA expression. Progesterone-stim ulated intrauterine expression of HDC mRNA, Intrauterine cytokine/chemokine mRNA was also hormonally regulated. This data allowed the possibility that one or more of these pro-inflammatory cytokines could be involved in regul ating intrauterine HDC mRNA production, Recombinant IL-1 alpha, IL-1 beta, MCP-1 and RANTES all failed to induce HDC mRNA expression in the preimplant ation uterus in a mouse pseudopregnancy model. At the same time, IL-1 beta induced the expression of mRNA for each of the four cytokines/chemokines. D espite the fact that these were also produced in the uterus during pregnanc y and were hormonally regulated, none of these cytokines induced intrauteri ne HDC mRNA expression. The data suggest that progesterone is involved in t he regulation of HDC mRNA expression in the preimplantation uterus, but IL- 1 alpha/beta, MCP-1 and RANTES, which have been reported to regulate histam ine synthesis during inflammatory processes, do not appear to play a role. (C) 2000 Academic Press.