Effects of ferrous ions on preoptic area neurones and luteinizing hormone secretion in the rat.

Ferrous ions (Fe2+) were applied by microiontophoresis of 29 neurones recordid from the forebrain of ten pro-oestrous rats. The spontaneous activity of 24 cells was reduced by Fe2+ and five units did not respond. No excitations were observed. Reproducible responses could not be obtained with ferric ions (Fe3+). Microinjection of 1 mul 200 mM-Fe2+ into the preoptic area of eight pro-oestrous rats produced a sharp increase in plasma LH levels. Similar treatment with saline was without effect. Rats anaesthetized with sodium pentobarbitone during the early afternoon of pro-oestrus ovulated overnight when injected with both Fe2+ and Fe3+. The experiments do not confirm the widely held belief that raised plasma LH levels following deposition of iron in the rostral hypothalamus result from increased firing of nerve cells.