Pubertal ovarian hormone exposure reduces the number of myelinated axons in the splenium of the rat corpus callosum

• Published in: Experimental neurology Vol. 209; no. 1; pp. 284 - 287
• Main Authors: Yates, M.A., Juraska, J.M.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Inc 01-01-2008; Elsevier
• Subjects: Adolescence; Animals; Axons - drug effects; Biological and medical sciences; Body Weight - physiology; Corpus Callosum - cytology; Corpus Callosum - drug effects; Corticosteroids; Estrogen; Female; Image Processing, Computer-Assisted; Injuries of the nervous system and the skull. Diseases due to physical agents; Medical sciences; Microscopy, Electron, Transmission; Myelin; Myelin Sheath - drug effects; Neurology; Oligdodendrocyte; Ovariectomy; Progesterone; Rats; Rats, Long-Evans; Sexual Maturation - physiology; Traumas. Diseases due to physical agents; Adolescence; Corticosteroids; Progesterone; Oligdodendrocyte; Myelin; Estrogen; Corticosteroid; Nervous system diseases; Rat; Rodentia; Axon; Corpus callosum; Ovarian hormone; Vertebrata; Mammalia; Animal; Sex steroid hormone
• ISSN: 0014-4886; 1090-2430
• DOI: 10.1016/j.expneurol.2007.09.013

The size of the female rat corpus callosum decreases in response to pubertal ovarian hormone exposure, but the underlying changes in axonal composition have not been examined. In the current study, animals underwent ovariectomy or sham surgery at day 20, and the number of myelinated and unmyelinated axons were examined in young adulthood (2 months) using electron microscopy. Ovariectomized animals had a greater number of myelinated axons compared to intact animals, while total axon number was not affected. Ovarian hormone exposure seems to limit the number of axons that become myelinated in the splenium, while not affecting the number of axons crossing through the region.