title: Varying responses of ovum transport in mice related to dose and time of administration of oestradiol.
abstract: The dose-response relationships between exogenous oestradiol and ovum transport in mice and the effect of treatment on different days of pregnancy were reinvestigated in detail. In addition, serum levels of oestradiol were measured, and their correlation with the various responses was examined. Control animals injected with vehicle alone had the majority of ova in oviductal loops 1 and 2; 3 and 4; or 6 and 7 on days 1, 2, or 3 of pregnancy, respectively. On day four, the majority of ova were found in the uterus. Varying the dose or time of administration of oestradiol determined qualitatively different responses. A single sc injection of oestradiol 5 micrograms or less on day 1 produced scattering of the embryos along the oviduct on day 3 and their accumulation in loops 7 and 8 on day 4, suggesting an increased randomness of the direction of propulsive forces, as well as decreased luminal permeability of the tubo-uterine junction. Doses of 25 and 125 micrograms injected on day 1 caused accelerated transport of ova, some of which entered the uterus as early as 8 hr after treatment. The predominant effect following injection of 1 micrograms on day 2 or days 1 and 2 was acceleration, indicating that oestradiol given on day 2 has opposite effect to and can counteract that of oestradiol given on day 1. Following injection of 25 or 125 micrograms, but not 5 micrograms, on day 1, plasma oestradiol remained significantly elevated through day 2, indicating that tube-locking results from high levels of plasma oestradiol restricted to day 1.(ABSTRACT TRUNCATED AT 250 WORDS)
mesh_terms: D000818:Animals; D004305:Dose-Response Relationship, Drug; D004958:Estradiol / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*; D005187:Fallopian Tubes / Q000187:drug effects* / Q000502:physiology; D005260:Female; D051379:Mice; D008807:Mice, Inbred BALB C; D010066:Ovum Transport / Q000187:drug effects*
chemical_list: D004958:Estradiol