Effects of Nicotine on Conceptus Cell Proliferation and Oviductal/Uterine Blood Flow in the Rat

Abstract

Daily administration of nicotine to rats during Days 0–5 of pregnancy delays loss of the zona pellucida, obliteration of the blastocyst cavity, and implantation (Card and Mitchell, 1979). Prior to implantation the unattached conceptus depends on oxygen and other essential metabolic substrates available within the lumen of the reproductive tract to sustain its continued growth and development. The availability of oxygen within the uterine lumen of the rat increases prior to implantation (Yochim and Mitchell, 1968) and declines rapidly upon vasoconstriction of the uterine vasculature (Mitchell and Yochim, 1968). Because conceptus development requires optimal oxygen tension (Brinster, 1972) and nicotine is a potent vasoactive substance, it was suggested that the nicotine-induced alterations in conceptus development and implantation may result, in part, from changes in reproductive tract blood flow (Hammer and Mitchell, 1979). The following study was undertaken to establish whether nicotine alters cell proliferation in embryos prior to implantation and if so whether such alterations are associated with reduced oviductal and/or uterine blood flow.