EFFECTS OF FERROUS IONS ON PREOPTIC AREA NEURONES AND LUTEINIZING HORMONE SECRETION IN THE RAT

Abstract

SUMMARY: Ferrous ions (Fe²⁺) were applied by microiontophoresis to 29 neurones recorded 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 μl 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.