title: Progesterone blocks estrogen neuroprotection from kainate in middle-aged female rats.
abstract: The neuroprotective effects of estrogen in young adult rodents are well established. Less well understood is how estrogen neuroprotection is affected by aging and interactions with progesterone. In this study, we investigated the effects of estrogen and continuous progesterone, both alone and in combination, on hippocampal neuron survival following kainate lesion in 14-month-old female rats entering reproductive senescence. Our results show that ovariectomy-induced hormone depletion did not significantly affect the extent of kainate-induced neuron loss. Treatment of ovariectomized rats with estrogen significantly reduced neuron loss, however this effect was blocked by co-administration of continuous progesterone. Treatment of ovariectomized rats with progesterone alone did not significantly affect kainate toxicity. These results provide new insight into factors that regulate estrogen neuroprotection, which has important implications for hormone therapy in postmenopausal women.
authors.affiliation: Neuroscience Graduate Program, Davis School of Gerontology, University of Southern California, 3715 McClintock Avenue, Los Angeles, CA 90089-0191, USA.
authors.forename: Jenna C
authors.initials: JC
authors.lastname: Carroll
authors.forename: Emily R
authors.initials: ER
authors.lastname: Rosario
authors.forename: Christian J
authors.initials: CJ
authors.lastname: Pike
mesh_terms: D000375:Aging / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D016923:Cell Death / Q000187:drug effects; D004967:Estrogens / Q000494:pharmacology*; D005260:Female; D006624:Hippocampus / Q000187:drug effects / Q000473:pathology; D007608:Kainic Acid / Q000633:toxicity; D009474:Neurons / Q000187:drug effects*; D018696:Neuroprotective Agents / Q000494:pharmacology*; D010052:Ovariectomy; D011374:Progesterone / Q000494:pharmacology*; D011372:Progestins / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011930:Reaction Time / Q000187:drug effects; D012640:Seizures / Q000139:chemically induced / Q000473:pathology
chemical_list: D004967:Estrogens; D018696:Neuroprotective Agents; D011372:Progestins; D011374:Progesterone; D007608:Kainic Acid
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