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To: Gauguin who wrote (31323)	7/9/1999 12:18:00 PM
From: Ilaine	Read Replies (1) \| Respond to of 71178

I don't know whether your hippocampus would benefit from estrogens - being as you're male and all. They'll probably figure it out after it's too late. >>>>>Granule cells in aging rats are sexually dimorphic in their response to estradiol. Miranda P, Williams CL, Einstein G Department of Neurobiology, Duke University Medical Center, Durham, North Carolina, 27710, USA. Normal aging comprises cognitive decline, including deterioration of memory. It has been suggested that this decline in memory is sexually dimorphic because of the cessation in gonadal steroid secretion that occurs during reproductive aging in female, but not male, mammals. We wondered whether neurons in brain regions associated with learning and memory underwent morphological changes that were dimorphic as well and whether cessation of the secretion of gonadal steroids influenced these morphological changes. To explore these questions, we deprived and restored estrogens to young and old gonadectomized females and males and studied the morphology of dentate granule cells by intracellular dye filling in a lightly fixed slice preparation. We found the following: (1) Aged female dentate granule cells deprived of gonadal steroids long-term have a paucity of dendritic spines compared with young females deprived short-term; however, aged male dentate granule cells deprived of gonadal steroids long-term have no decrease in dendritic spines compared with young males deprived short-term. (2) Aged female dentate granule cells with long-term estrogen replacement at either high or low levels still had a decline in spine density. (3) Aged female dentate granule cells with short-term estradiol replacement had spine density increased to levels normally observed in young adults, whereas aged males with short-term estradiol replacement had decreased spine density. These data suggest that the response of rat dentate granule cells to aging and estradiol is sexually dimorphic and that, in females, the responsiveness of granule cells depends on the temporal pattern of estradiol replacement.<<<<<

To: Gauguin who wrote (31323)	7/9/1999 12:24:00 PM
From: Ilaine	Respond to of 71178

In fact, maybe you ought to be increasing your testosterone - and I promise this is the last abstract for today: >>>>>Brain Res 1999 Mar 13;821(2):383-91 Relations of hippocampal volume and dentate gyrus width to gonadal hormone levels in male and female meadow voles. Galea LA, Perrot-Sinal TS, Kavaliers M, Ossenkopp KP Department of Psychology, University of British Columbia, 2136 West Mall, Vancouver, BC, Canada. lgalea@psych.ubc.ca The present study examined hippocampal volume and dentate gyrus width and their relations to gonadal hormone levels in adult male and female meadow voles, Microtus pennsylvanicus. Females were split into High and Low Estradiol groups based on the median estradiol level. Males were similarly split into High and Low Testosterone groups. Contrary to previous reports in wild meadow voles, there was no evidence of an overall sex difference in hippocampal volume. However, when male-female comparisons were limited to High Testosterone males and Low Estradiol females a significant sex difference in hippocampal volume favouring males did emerge. Hippocampal volume in males was related to testosterone level, with High Testosterone males having significantly larger hippocampi than Low Testosterone males. Similarly, there was a significant influence of plasma estradiol level on hippocampal volume and left dentate gyrus width, with High Estradiol females having larger hippocampi and dentate gyrus width than Low Estradiol females. In addition, consistent with previous findings in the laboratory rat, there were sex differences favouring males in right dentate gyrus width. These findings show that there is a complex relationship between hippocampal volume, dentate gyrus width and gonadal hormone levels in male and female meadow voles. Copyright 1999 Published by Elsevier Science B.V. PMID: 10064825, UI: 99165641<<<<<