Postsynaptic Effects of Prolactin and Estrogen on Arcuate Neurons in Rat Hypothalamic Slices

Abstract

The effects of 17β-estradiol (E₂) and prolactin (PRL) on the excitability of neurons in the arcuate nucleus were examined using hypothalamic slices obtained from ovariectomized rats. Neither E₂ nor PRL affected the excitability of neurons having antidromic responses due to median eminence stimulation. On the other hand, E₂ and PRLaltered the spontaneous activity of unidentified neurons, which were not activated by median eminence stimulation, by 6 and 11 %, respectively. Both excitatory and inhibitory responses were recorded, which were not abolished in the low Ca²⁺/high Mg²⁺ medium. These results suggest that E₂ and PRL can rapidly modulate the excitability of some arcuate, but presumably not tuberoinfundibular, neurons by acting directly on the postsynaptic membrane.