[Abstract Title]. - Society for Neuroscience

Abstract: During the short four day estrous cycle of the female hamster various behavioral
(lordosis, vocalization and aggression) and autonomic adaptations occur. Presumably, these
changes are under ovarial hormonal control. Recently, we described a distinct estrogen receptorα
immunoreactive (ER-α-IR) cell group, now called nucleus para-retroambiguus (NPRA), in the
caudal ventrolateral medulla. Neurons of this group project to the ipsilateral intermediolateral
cell column in the thoracic and upper lumbar cord. Clearly, the NPRA is part of an estrogensensitive
neuronal network and the same applies to the region containing the commissural part of
the solitary tract nucleus (NTScom) and the A2 group, here called NTScom/A2.
Estrogen is known to modulate neuronal ultrastructure in various brain areas and spinal cord, but
not in the caudal brainstem. Because we assumed that the NPRA plays a role in estrous cycle
related adaptations, we hypothesized the occurrence of plasticity in this nucleus.
In the present study we examined morphological changes of axo-dendritic relationships in NPRA
and NTScom/A2 in estrous, diestrous and ovariectomized (OVX) hamsters, using immunoelectron
microscopy and the 1D5 anti-ER-α antibody.
Ultrastructural analysis revealed that the ratio ”axon terminals surface/dendrite surface” was
significantly increased in both the NPRA and NTScom/A2 during the estrous phase compared to
the OVX and diestrous conditions. Enlargement of the axon terminal fields contacting more
dendrites was the main cause for the “axonal terminal-dendritic-ratio” shift.
Estrous cycle-induced plasticity is present in the NPRA, and in the NTScom/A2 group. Our
findings support our hypothesis that estrogen-sensitive neuronal networks in the caudal
brainstem display structural plasticity, probably to modulate steroid hormone dependent
behaviors or autonomic adaptations.
Disclosures: P.O. Gerrits , None; H. de Weerd, None; R. Kortekaas, None; A. Algra,
None; L.J. Mouton, None; H.J.J.L. Van der Want, None; J.G. Veening, None.
Poster
239. Structural Plasticity at Synapses I
Time: Sunday, November 16, 2008, 1:00 pm - 5:00 pm
Program#/Poster#: 239.8/E5
Topic: B.08.i. Structural plasticity
Title: A role for ProSAP/Shank protein SAM domains in dynamic processes at postsynaptic
densities of excitatory synapses
Authors: *A. M. GRABRUCKER 1 , B. VAIDA 1 , A. DOLNIK 1 , C. PROEPPER 1 , M. R.
KREUTZ 2 , E. GUNDELFINGER 2 , T. M. BOECKERS 1 ;
1 Inst. of Anat., Univ. Ulm, Ulm, Germany; 2 Leibniz Inst. for Neurobio., Magdeburg, Germany