Ovarian hormone-induced reorganization of oxytocin-labeled dendrites and synapses lateral to the hypothalamic ventromedial nucleus in female rats

Authors

  • Gerald D. Griffin,

    Corresponding author
    1. Neuroscience Graduate Group, University of Pennsylvania, Philadelphia, Pennsylvania 19104
    • Department of Microbiology, University of Pennsylvania, 3610 Hamilton Walk, 302C Johnson Pavilion, Philadelphia, PA 19104-6241
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  • Sarah L. Ferri-Kolwicz,

    1. Department of Psychology, University of Pennsylvania, Philadelphia, Pennsylvania 19104
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  • Beverly A.S. Reyes,

    1. Department of Neurosurgery, Thomas Jefferson University, Philadelphia, Pennsylvania 19107
    2. Farber Institute for Neurosciences, Thomas Jefferson University, Philadelphia, Pennsylvania 19107
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  • Elisabeth J. Van Bockstaele,

    1. Department of Neurosurgery, Thomas Jefferson University, Philadelphia, Pennsylvania 19107
    2. Farber Institute for Neurosciences, Thomas Jefferson University, Philadelphia, Pennsylvania 19107
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  • Loretta M. Flanagan-Cato

    1. Neuroscience Graduate Group, University of Pennsylvania, Philadelphia, Pennsylvania 19104
    2. Department of Psychology, University of Pennsylvania, Philadelphia, Pennsylvania 19104
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Errata

This article is corrected by:

  1. Errata: Ovarian hormone-induced reorganization of oxytocin-labeled dendrites and synapses lateral to the hypothalamic ventromedial nucleus in female rats Volume 520, Issue 8, Article first published online: 1 June 2012

Abstract

Central oxytocin (OT) modulates many social behaviors, including female rat sexual receptivity, quantified as the copulatory stance known as lordosis. The expression of the lordosis response is modulated by OT action in the ventromedial nucleus of the hypothalamus (VMH), as demonstrated by behavioral pharmacology experiments. However, the subcellular localization of OT in this brain region has been unclear. We tested the hypothesis that ovarian hormones reorganize OT-labeled pre- or postsynaptic elements in the fiber complex lateral to the VMH by using immunoelectron microscopy. OT immunolabeling occurred in axonal boutons identified by the presence of small, clear synaptic vesicles and double labeling with the presynaptic markers synaptophysin and vesicular glutamate transporter 2. OT immunoreactivity also was observed in dendritic profiles, verified with double labeling for the dendrite-specific marker microtubule-associated protein 2. Ovarian hormones did not alter the density of axonal boutons; however, estradiol treatment reduced the density of dendritic profiles by 34%. This effect was reversed when progesterone was given subsequent to estradiol. The effect of estradiol treatment was specific to dendrites that lacked OT immunostaining; the density of OT-labeled dendritic profiles remained constant during estradiol treatment. With the estradiol-induced exit of non-OT-labeled dendritic profiles, the remaining OT-labeled dendritic profiles experienced an increase in their number of synaptic contacts. Thus, hormone treatments that mimic the 4-day rat estrous cycle provoke a chemically coded reorganization of dendrite innervation in the fiber plexus lateral to the VMH that may underlie the hormone-specific effect of OT on reproductive behavior. J. Comp. Neurol. 518:4531–4545, 2010. © 2010 Wiley-Liss, Inc.

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