Hyperpolarization of hypothalamic parvocellular neurons by 17 beta-estradiol and their identification through intracellular staining with procion yellow.
Intracellular recordings and injections of procion yellow (PY) were made in parvocellular neurons in hypothalamic slices of female guinea pigs. Eighty-five neurons, with an average resting membrane potential of -35 mV, were recorded in the arcuate (ARC) ventromedial (VM), and in the cell-poor zones between the ARC and VM. Eleven of the ARC neurons and four neurons from the cell-poor zone could be driven antidromically by median eminence (ME) stimulation, nine other neurons from the three areas could be driven orthodromically by stria terminalis (ST) stimulation. Twenty-eight parvocellular neurons were tested with 17 beta-estradiol (E2), which was applied in the bathing medium as the free steroid. Eleven neurons (nine ARC and two cell-poor-zone neurons) were hyperpolarized 2 to 24 mV by 10(-10) M E2 concentrations. 10(-8) M estrone concentration was without effect on three of these cells. Through the intracellular injection of PY, the estrogen-sensitive neurons (N = 11) were identified as small fusiform cells with few dendrites. Spine-like appendages were found on only one of these cells. None of the larger pyramidal-like neurons of these areas responded to the application of E2.
D000818:Animals; D046508:Culture Techniques; D004558:Electric Stimulation; D004958:Estradiol / Q000494:pharmacology*; D005071:Evoked Potentials / Q000187:drug effects; D005260:Female; D006168:Guinea Pigs; D007031:Hypothalamus / Q000166:cytology / Q000187:drug effects*; D008473:Median Eminence / Q000187:drug effects; D009434:Neural Pathways / Q000187:drug effects; D009474:Neurons / Q000187:drug effects / Q000648:ultrastructure; D009435:Synaptic Transmission / Q000187:drug effects*; D013787:Thalamic Nuclei / Q000187:drug effects
D004958:Estradiol