Acute responses to estradiol replacement in the olfactory system of apoE-deficient and wild-type mice

Epidemiological studies suggest that estrogen therapy protects against clinical expression of chronic neurological diseases. These beneficial effects of estrogen therapy are highly modified by apolipoprotein E (apoE) through an unknown mechanism. We examined the short-term effects of estradiol replacement in ovariectomized mice on apoE expression and markers for cell proliferation, reactive gliosis, neuronal maturation, and synaptogenesis in the primary olfactory pathway of wild-type (WT) and apoE knockout (KO) mice. Three days of estradiol replacement increased apoE expression in the olfactory nerve and in the glomerular layer. Estradiol treatment also increased cell proliferation, total cell numbers, number of mature neurons in the olfactory epithelium, and reactive astrocyte numbers in the olfactory bulb (OB) in both WT and KO mice. We also found that estradiol increased glomerular synaptophysin (Syn), but the magnitude of increase was potentiated by the presence of apoE. This data suggest that apoE may be necessary to elicit the complete effect of estradiol on Syn upregualtion

Acute responses to estradiol replacement in the olfactory system of apoE-deficient and wild-type mice

Epidemiological studies suggest that estrogen therapy protects against clinical expression of chronic neurological diseases. These beneficial effects of estrogen therapy are highly modified by apolipoprotein E (apoE) through an unknown mechanism. We examined the short-term effects of estradiol replacement in ovariectomized mice on apoE expression and markers for cell proliferation, reactive gliosis, neuronal maturation, and synaptogenesis in the primary olfactory pathway of wild-type (WT) and apoE knockout (KO) mice. Three days of estradiol replacement increased apoE expression in the olfactory nerve and in the glomerular layer. Estradiol treatment also increased cell proliferation, total cell numbers, number of mature neurons in the olfactory epithelium, and reactive astrocyte numbers in the olfactory bulb (OB) in both WT and KO mice. We also found that estradiol increased glomerular synaptophysin (Syn), but the magnitude of increase was potentiated by the presence of apoE. This data suggest that apoE may be necessary to elicit the complete effect of estradiol on Syn upregualtion

Acute responses to estradiol replacement in the olfactory system of apoE-deficient and wild-type mice

Epidemiological studies suggest that estrogen therapy protects against clinical expression of chronic neurological diseases. These beneficial effects of estrogen therapy are highly modified by apolipoprotein E (apoE) through an unknown mechanism. We examined the short-term effects of estradiol replacement in ovariectomized mice on apoE expression and markers for cell proliferation, reactive gliosis, neuronal maturation, and synaptogenesis in the primary olfactory pathway of wild-type (WT) and apoE knockout (KO) mice. Three days of estradiol replacement increased apoE expression in the olfactory nerve and in the glomerular layer. Estradiol treatment also increased cell proliferation, total cell numbers, number of mature neurons in the olfactory epithelium, and reactive astrocyte numbers in the olfactory bulb (OB) in both WT and KO mice. We also found that estradiol increased glomerular synaptophysin (Syn), but the magnitude of increase was potentiated by the presence of apoE. This data suggest that apoE may be necessary to elicit the complete effect of estradiol on Syn upregualtion

Comet assay in marine microalgae: DNA damage in Dunaliella tertiolecta Butcher 1959 caused by exposure to 4-nitroquinoline-N-oxide and benzo[a]pyrene

Dunaliella tertiolecta, uma alga verde fitoplanctônica de ampla distribuição no ambiente marinho, foi escolhida como organismo teste para estudar a possibilidade de ser utilizada no ensaio cometa, um teste de detecção de danos no DNA em células individualizadas muito utilizado na ecotoxicologia. Essas algas foram facilmente lisadas pela solução de lise alcalina iônica, seus cometas foram corados eficientemente pelo brometo de etídio e pela prata, e a análise por índice de danos apresentou boa correlação com momento de cauda, comprimento de cauda e porcentagem de DNA na cauda. As algas foram expostas a concentrações crescentes de 4-nitroquinolina-N-óxido (4NQO) e benzo[a]pireno (BAP) por 1, 2 e 4 h no escuro. Após somente 1 h de exposição, observou-se um aumento significativo de danos no DNA das algas expostas a 0,25 µM de 4NQO, demonstrando a sensibilidade das mesmas em relação a células de animais. Os dados obtidos da exposição ao BAP não foram consistentes e necessitam de verificação. A metabolização de BAP em compostos tóxicos pelas algas e o efeito das condições de luminosidade antes e durante as exposições são discutidos. Os resultados indicam que D. tertiolecta pode ser utilizada em laboratório para avaliação de genotoxicidade na água através do ensaio cometa.D. tertiolecta, a phytoplanktonic green algae with ubiquitous distribution in the marine environment, was chosen as a test organism to study the possibility of being used in the comet assay, a frequently used test in ecotoxicology to detect DNA damage in single cells. These algae were easily lised by the alkaline ionic lysis solution, their comets were efficiently stained by ethidium bromide and silver and the damage index was well correlated to tail moment, tail length and percentage of DNA in the tail. The algae were exposed to increasing concentrations of 4-nitroquinoline-N-oxide (4NQO) and benzo[a]pyrene (BAP) for 1, 2 and 4 h in the dark. After 1 h exposure, a significant increase in the DNA damage of algae exposed to 0,25 µM of 4NQO was observed, demonstrating their sensitivity in relation to cells from animals. The data of BAP exposure were not consistent and need further verification. The metabolization of BAP to toxic compounds by algae and the light conditions before and during exposure are discussed. The results indicate that D. tertiolecta can be used in laboratory to evaluate water genotoxicity with comet assay

Long-term effects of estradiol replacement in the olfactory system

Olfactory dysfunction often precedes other clinical symptoms in chronic neurodegenerative diseases like Alzheimer’s and Parkinson’s disease. Estrogen deficiency and apoE genotype are known risk factors in these diseases and these factors also affect olfaction. Therefore we examined the effects of estradiol replacement following ovariectomy on expression of apoE and markers of cell proliferation, neuronal maturation, synaptogenesis and reactive gliosis in the primary olfactory pathway of wild-type (WT) and apoE knockout (KO) mice. Estradiol replacement increased apoE staining in the olfactory nerve and glomerular layers. Estradiol increased astrocyte density and olfactory epithelium (OE) thickness regardless of the genotype. In addition estradiol treatment increased the number of mature neurons in the OE and glomerular synaptophysin in both genotypes, but the magnitude of increase was greater in the WT than in the KO mice. These data suggest that estrogen and apoE act synergistically to minimize the loss of mature sensory neurons and synapses following ovariectom