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Early estrogen‐induced nuclear changes in rat hypothalamic ventromedial neurons: An ultrastructural and morphometric analysis
Author(s) -
Jones Kathryn J.,
Pfaff Donald W.,
McEwen Bruce S.
Publication year - 1985
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/cne.902390302
Subject(s) - nucleoplasm , nucleolus , biology , heterochromatin , ovariectomized rat , cell nucleus , endoplasmic reticulum , endocrinology , medicine , estrogen , nucleus , chromatin , microbiology and biotechnology , genetics , dna
Alterations in the fine structure of nuclei of ventromedial hypothalamic neurons in ovariectomized (OVX) rats after either a 2‐hour exposure to estradiol (E 2 ) or a discontinuous exposure (2 hours E 2 /7 hours off/2 hours E 2 ), previously shown sufficient for female rat sexual behavior (Parsons et al., 1982a), were examined with the electron microscope. Morphometric measurements of nucleolar, nuclear, and somal areas, and nuclear shape and perimeter were accomplished at the light microscope level. After 2 hours of E 2 , the appearance of the nucleoplasm was altered, with a decrease in the small, scattered clumps of heterochromatin. Nuclear shape appeared dramatically altered from nonspherical, invaginated profiles toward spherical, smooth profiles. Nucleolar, nuclear, and somal hypertrophy were evident. In addition, stacked rough endoplasmic reticulum was present more frequently in E 2 ‐treated than control OVX neurons. After the discontinuous (2 hours/7 hours/2 hours) E 2 treatment, progressive loss of small clumps of heterochromatin along the nuclear envelope as well as in the nucleoplasm had occurred. Decrease in a large heterochromatin clump along the nuclear envelope was correlated with an increase in nucleolus‐associated chromatin. As determined by a distribution analysis, these estrogen‐induced nuclear changes co‐occurred more frequently than predicted from mutual independence. These findings, the marked co‐occurrence of E 2 ‐induced changes in 30% or more of the cells, and the differences between the 2‐hour E 2 and the 2‐hour/7‐hour/2‐hour group are consistent with a cascade of cell nuclear changes in the first few hours after estrogen onset.