Binding of Tritiated Oestradiol by Certain Cells in Autonomic Ganglia in the Mouse

Abstract

Oestrogens in high doses have been shown to be potent reticuloendothelial stimulants (Nicol, Bilbey, Charles, Cordingley & Vernon-Roberts, 1964). In the course of an investigation into the cellular mechanism of this effect, it seemed relevant to study the distribution throughout the reticuloendothelial system (RES) of tritiated oestrogens administered parenterally. By chance, localization to peripheral autonomic nervous tissue was observed. Since it is known that oestrogens are selectively taken up by certain areas in the CNS, notably the hypothalamus, wherein resides higher autonomic control, and since in these sites oestrogens have a significant effect on behaviour (see Harris, 1965;Michael, 1965;Palka & Sawyer, 1966) it seemed that this chance morphological observation might have functional significance and should therefore be reported.The animals used were white mice (20\p=n-\25g.) from a closed colony kept in the University of Sheffield animal house. [6,7-3H]Oestradiol (Radiochemical Centre, Amersham) was administered s.c. or i.p. in doses of 50\p=n-\200 \g=m\c(oestrogenic dose of 0\m=.\\p=n-\110 \g=m\g.depending on specific activity) to adult animals of either sex. The animals were killed after 15 min., 1, 2, 4, 6, 8 or 24 hr. and tissues excised, fixed in 4 % formaldehyde neutralized with calcium carbonate and embedded in paraffin wax. Stripping film autoradiographs were prepared using Kodak AR 10 emulsion, exposed for 4-12 weeks, developed in D19b developer, and counterstained with New Méthylène Blue. In addition to 20 normal animals, one pregnant female, two full-term foetuses and two newborn mice were examined. As a test for chemical artifacts, autoradiographs were prepared with a layer of formvar between the slide and the emulsion.Slight but detectable radioactivity was present in the liver, spleen, and uterus 1 hr. after administration, but not at later periods. The only highly significant activity present was in nerve ganglia on the posterior abdominal wall. Because these were not identified with the naked eye, their precise topographical relationships are not clear. However, positive ganglia were found near the splenic artery (Plate, figs. 1,2) and alongside the aorta at the level of the kidneys. Positive ganglia were not identified in the paravertebral sympathetic chain; but this structure is very small in the thorax, and was not always identified in the abdomen. These negative findings may therefore not be significant. Prior dipping in 1 % formvar did not prevent the reaction. In the ganglia, activity was present only in large cells which