Document Detail

Sex differences and the roles of sex steroids in apoptosis of sexually dimorphic nuclei of the preoptic area in postnatal rats.
MedLine Citation:
PMID:  19226350     Owner:  NLM     Status:  MEDLINE    
The brain contains several sexually dimorphic nuclei that exhibit sex differences with respect to cell number. It is likely that the control of cell number by apoptotic cell death in the developing brain contributes to creating sex differences in cell number in sexually dimorphic nuclei, although the mechanisms responsible for this have not been determined completely. The milieu of sex steroids in the developing brain affects sexual differentiation in the brain. The preoptic region of rats has two sexually dimorphic nuclei. The sexually dimorphic nucleus of the preoptic area (SDN-POA) has more neurones in males, whereas the anteroventral periventricular nucleus (AVPV) has a higher cell density in females. Sex differences in apoptotic cell number arise in the SDN-POA and AVPV of rats in the early postnatal period, and an inverse correlation exists between sex differences in apoptotic cell number and the number of living cells in the mature period. The SDN-POA of postnatal male rats exhibits a higher expression of anti-apoptotic Bcl-2 and lower expression of pro-apoptotic Bax compared to that in females and, as a potential result, apoptotic cell death via caspase-3 activation more frequently occurs in the SDN-POA of females. The patterns of expression of Bcl-2 and Bax in the SDN-POA of postnatal female rats are changed to male-typical ones by treatment with oestrogen, which is normally synthesised from testicular androgen and affects the developing brain in males. In the AVPV of postnatal rats, apoptotic regulation also differs between the sexes, although Bcl-2 expression is increased and Bax expression and caspase-3 activity are decreased in females. The mechanisms of apoptosis possibly contributing to the creation of sex differences in cell number and the roles of sex steroids in apoptosis are discussed.
S Tsukahara
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Review    
Journal Detail:
Title:  Journal of neuroendocrinology     Volume:  21     ISSN:  1365-2826     ISO Abbreviation:  J. Neuroendocrinol.     Publication Date:  2009 Mar 
Date Detail:
Created Date:  2009-04-14     Completed Date:  2009-08-10     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8913461     Medline TA:  J Neuroendocrinol     Country:  England    
Other Details:
Languages:  eng     Pagination:  370-6     Citation Subset:  IM    
Research Centre for Environmental Risk, National Institute for Environmental Studies, Tsukuba, Ibaraki, Japan.
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MeSH Terms
Apoptosis / physiology*
Caspase 3 / metabolism
Cell Count
Estrogens / metabolism
Gonadal Steroid Hormones / metabolism*
Mitochondria / physiology
Neurons / physiology
Preoptic Area / physiology*
Proto-Oncogene Proteins c-bcl-2 / metabolism
Sex Characteristics*
bcl-2-Associated X Protein / metabolism
Reg. No./Substance:
0/Bax protein, rat; 0/Estrogens; 0/Gonadal Steroid Hormones; 0/Proto-Oncogene Proteins c-bcl-2; 0/bcl-2-Associated X Protein; EC 3.4.22.-/Caspase 3

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