Elsevier

Hormones and Behavior

Volume 40, Issue 2, September 2001, Pages 178-182
Hormones and Behavior

Regular Article
The Synaptic Organization of VMH Neurons That Mediate the Effects of Estrogen on Sexual Behavior

https://doi.org/10.1006/hbeh.2001.1679Get rights and content

Abstract

Estrogen acts in the hypothalamic ventromedial nucleus (VMH) of female rats to promote sexual behavior, as typified by the lordosis response. Morphological changes in the VMH, such as increased synaptic profiles and increased dendritic spines, suggest that estrogen may modulate behavior by altering VMH synaptic organization. To understand the significance of these changes, this laboratory has been investigating the functional classes of lordosis-relevant neurons and their local connectivity. A neurotropic virus, pseudorabies virus (PRV), was used to transneuronally label the CNS network that controls the lordosis-producing muscles. When PRV was placed in the lumbar epaxial muscles, it was sequentially detected in the lumbar ventral horn, the medullary reticular formation, the periaqueductal gray, and finally the VMH. Subsequent analysis showed that the population of VMH neurons that were initially infected with PRV largely resided beyond the cluster of estrogen receptor-containing neurons. In a separate study, VMH neurons were visualized with Lucifer yellow, and their morphology was analyzed using confocal microscopy. Such analysis confirmed that estrogen treatment increased dendritic spines in the VMH. The particular VMH neurons in this study did not express nuclear estrogen receptor, which suggests that estrogen can increase spine density indirectly. These results represent initial steps toward unraveling the local circuit that mediates estrogenic action on a specific reproductive behavior.

References (26)

  • L.M. Flanagan et al.

    Induction of Fos immunoreactivity in oxytocin neurons after sexual activity in female rats

    Neuroendocrinology

    (1993)
  • M. Frankfurt et al.

    Gonadal steroids modify dendritic spine density in ventromedial hypothalamic neurons: A golgi study in the adult rat

    Neuroendocrinology

    (1990)
  • Cited by (0)

    1

    To whom correspondence and reprint requests should be addressed. Fax: (215) 898-7301. E-mail: [email protected].

    View full text