title: Reduced aging defects in estrogen receptive brainstem nuclei in the female hamster.
abstract: The nucleus pararetroambiguus (NPRA) and the commissural nucleus of the solitary tract (NTScom) show estrogen nuclear receptor-α immunoreactivity (nuclear ER-α-IR). Both cell groups are involved in estrous cycle related adaptations. We examined in normally cycling aged hamsters the occurrence/amount/frequency of age-related degenerative changes in NPRA and NTScom during estrus and diestrus. In 2640 electron microscopy photomicrographs plasticity reflected in the ratio of axon terminal surface/dendrite surface (t/d) was morphometrically analyzed. Medial tegmental field (mtf, nuclear ER-α-IR poor), served as control. In aged animals, irrespective of nuclear ER-α-IR+ or nuclear ER-α-IR- related cell groups, extensive diffuse degenerative structural aberrations were observed. The hormonal state had a strong influence on t/d ratios in NPRA and NTScom, but not in mtf. In NPRA and NTScom, diestrous hamsters had significantly smaller t/d ratios (NPRA, 0.750 ± 0.050; NTScom, 0.900 ± 0.039) than the estrous hamsters (NPRA, 1.083 ± 0.075; NTScom, 1.204 ± 0.076). Aging affected axodendritic ratios only in mtf (p < 0.001).
  
  
  CONCLUSIONS
  in the female hamster brain, estrous cycle-induced structural plasticity is preserved in NPRA and NTScom during aging despite the presence of diffuse age-related neurodegenerative changes.
authors.affiliation: Department of Neuroscience, Section of Anatomy, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands. p.o.gerrits@med.umcg.nl
authors.forename: Peter O
authors.initials: PO
authors.lastname: Gerrits
authors.forename: Rudie
authors.initials: R
authors.lastname: Kortekaas
authors.forename: Jan G
authors.initials: JG
authors.lastname: Veening
authors.forename: Henk
authors.initials: H
authors.lastname: de Weerd
authors.forename: Johannes J L
authors.initials: JJ
authors.lastname: van der Want
mesh_terms: D000367:Age Factors; D000375:Aging; D000818:Animals; D001933:Brain Stem / Q000166:cytology* / Q000378:metabolism; D006224:Cricetinae; D047628:Estrogen Receptor alpha / Q000378:metabolism; D004967:Estrogens / Q000378:metabolism*; D030762:Estrous Cycle / Q000378:metabolism; D005260:Female; D008297:Male; D046529:Microscopy, Electron, Transmission; D009474:Neurons / Q000378:metabolism* / Q000648:ultrastructure; D012726:Sexual Behavior, Animal / Q000502:physiology*; D013997:Time Factors
chemical_list: D047628:Estrogen Receptor alpha; D004967:Estrogens