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J Comp Neurol

Title:		Sexual dimorphism in neuronal number of the posterodorsal medial amygdala is independent of circulating androgens and regional volume in adult rats
Author(s):		Morris JA; Jordan CL; Breedlove SM;
Address:		"Neuroscience Program, Michigan State University, East Lansing, Michigan 48824-1101, USA"
Journal Title:		J Comp Neurol
Year:		2008
Volume:		506
Issue:		5
Page Number:		851 - 859
DOI:		10.1002/cne.21536
ISSN/ISBN:		0021-9967 (Print) 0021-9967 (Linking)
Abstract:		"The posterodorsal medial amygdala (MePD) in rodents integrates olfactory and pheromonal information, which, coupled with the appropriate hormonal signals, may facilitate or repress reproductive behavior in adulthood. MePD volume and neuronal soma size are greater in male rats than in females, and these sexual dimorphisms are maintained by adult circulating hormone levels. Castration of adult males causes these measures to shrink to the size seen in females 4 weeks later, whereas testosterone treatment of adult females for 4 weeks enlarges these measures to the size of males. We used stereological methods to count the number of cells in the MePD and found that, in addition to the sex difference in regional volume and soma size, males also have more MePD neurons than do females, yet these numbers are unaffected by the presence or absence of androgen in adults of either sex. Males also have more glial cells than do females, but, in contrast to the effects on neuronal number, the number of glial cells is affected by androgen in the right MePD of both sexes and, therefore, may contribute to regional volume changes in adulthood in that hemisphere. Thus, regional volume, neuronal size, and glial numbers vary in the MePD of adult rats in response to circulating androgens, but neuronal number does not. These results suggest that the sex difference in neuronal number in the rat MePD may be 'organized' by androgens prior to adulthood, whereas regional volume, neuronal size, and glial numbers can be altered by androgens in adulthood"
Keywords:		"Amygdala/*cytology/physiology Analysis of Variance Animals Cell Count Female Functional Laterality/physiology Male Neuroglia/*cytology/physiology Neuronal Plasticity/physiology Neurons/*cytology/physiology Organ Size Rats Rats, Long-Evans Sex Characterist;Neuroscience;"
Notes:		"MedlineMorris, John A Jordan, Cynthia L Breedlove, S Marc eng NS0450195/NS/NINDS NIH HHS/ NS28421/NS/NINDS NIH HHS/ Comparative Study Research Support, N.I.H., Extramural 2007/12/14 J Comp Neurol. 2008 Feb 10; 506(5):851-9. doi: 10.1002/cne.21536"