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Effects of estrogen replacement therapy on the myelin sheath ultrastructure of myelinated fibers in the white matter of middle‐aged ovariectomized rats
Author(s) -
He Qi,
Luo Yanmin,
Lv Fulin,
Xiao Qian,
Chao Fenglei,
Qiu Xuan,
Zhang Lei,
Gao Yuan,
Xiu Yun,
Huang Chunxia,
Tang Yong
Publication year - 2018
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.24366
Subject(s) - ovariectomized rat , white matter , myelin , ultrastructure , endocrinology , medicine , estrogen , stereology , biology , morris water navigation task , anatomy , chemistry , central nervous system , hippocampus , magnetic resonance imaging , radiology
Abstract The effects of estrogen replacement therapy (ORT) on white matter and the myelin sheath ultrastructure in the white matter of middle‐aged ovariectomized (OVX) rats were investigated in this study. Middle‐aged rats were ovariectomized and divided into a placebo replacement (OVX + O) group and an estrogen replacement (OVX + E) group. Then, the Morris water maze, electron microscope techniques, and stereological methods were used to investigate the effects of ORT on spatial learning capacity, white matter volume and the myelin sheath ultrastructure in the white matter. We found that the spatial learning capacity of the OVX + E rats was significantly improved compared with that of the OVX + O rats. When compared with that of OVX + O rats, the total volume of the myelin sheaths in the white matter of the OVX + E rats was significantly increased by 27%, and the difference between the outer perimeter and inner perimeter of the myelin sheaths of the white matter in the OVX + E rats increased significantly by 12.6%. The myelinated fibers with mean diameters of 1.2–1.4 μm were significantly longer (46.1%) in the OVX + E rats; the difference between the mean diameter of myelinated fibers and the mean diameter of axons (0–0.4 μm) was significantly increased by 21.6% in the OVX + E rats. These results suggested that ORT had positive protective effects on the spatial learning ability and on the myelin sheath ultrastructure in the white matter of middle‐aged OVX rats.