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1.
Life Sci ; 86(21-22): 832-8, 2010 May 22.
Article in English | MEDLINE | ID: mdl-20394757

ABSTRACT

AIMS: The aim of the present study was to investigate the effects of different periods of ovariectomy and 17beta-estradiol replacement on apoptotic cell death and expression of members of the Bcl-2 family in the rat hippocampus. MAIN METHODS: Hippocampi were obtained from rats in proestrus, ovariectomized (15 days, 21 days and 36 days), ovariectomized for 15 days and then treated with 17beta-estradiol for 7 or 21 days, and rats ovariectomized and immediately treated with 17beta-estradiol for 21 days. The expression of Bcl-2 and Bax and the number of apoptotic cells were determined. KEY FINDINGS: Ovariectomy decreased Bcl-2 expression and increased Bax expression and the number of apoptotic cells. Replacement with 17beta-estradiol (21 days) throughout the post-ovariectomy period reduced the number of apoptotic cells to the control levels, and prevented the effects of ovariectomy on Bax expression, but only partially restored the Bcl-2 expression. After 15 days of ovariectomy, the replacement with 17beta-estradiol for 21 days, but not for 7 days, restored the Bcl-2 and Bax expression and the percentage of apoptotic cells to the levels found in the proestrus control. SIGNIFICANCE: The present results show that a physiological concentration of 17beta-estradiol may help maintain long-term neuronal viability by regulating the expression of members of the Bcl-2 family. Even after a period of hormonal deprivation, treatment with 17beta-estradiol is able to restore the expression of Bax and Bcl-2 to control levels, but the duration of the treatment is a key factor to obtain the desired effect. These data provide new understanding into the mechanisms contributing to the neuroprotective action of estrogen.


Subject(s)
Apoptosis/drug effects , Estradiol/pharmacology , Hippocampus/drug effects , Ovariectomy/adverse effects , Animals , Apoptosis/physiology , Blotting, Western , Female , Hippocampus/chemistry , Hippocampus/physiopathology , Proto-Oncogene Proteins c-bcl-2/analysis , Rats , Rats, Wistar , bcl-2-Associated X Protein/analysis
2.
Life sci. (1973) ; 86(21-22): 832-838, 2010.
Article in English | Sec. Est. Saúde SP, SESSP-IBPROD, Sec. Est. Saúde SP, SESSP-IBACERVO | ID: biblio-1064619

ABSTRACT

The aim of the present study was to investigate the effects of different periods of ovariectomy and 17â- estradiol replacement on apoptotic cell death and expression of members of the Bcl-2 family in the rat hippocampus. Hippocampi were obtained from rats in proestrus, ovariectomized (15 days, 21 days and 36 days), ovariectomized for 15 days and then treated with 17â-estradiol for 7 or 21 days, and rats ovariectomized and immediately treated with 17â-estradiol for 21 days. The expression of Bcl-2 and Bax and the number of apoptotic cells were determined. Ovariectomy decreased Bcl-2 expression and increased Bax expression and the number of apoptotic cells. Replacement with 17â-estradiol (21 days) throughout the post-ovariectomy period reduced the number of apoptotic cells to the control levels, and prevented the effects of ovariectomy on Baxexpression, but only partially restored the Bcl-2 expression. After 15 days of ovariectomy, the replacementwith 17â-estradiol for 21 days, but not for 7 days, restored the Bcl-2 and Bax expression and the percentageof apoptotic cells to the levels found in the proestrus control.The present results show that a physiological concentration of 17â-estradiol my help maintainlong-term neuronal viability by regulating the expression of members of the Bcl-2 family. Even after a period of hormonal deprivation, treatment with 17â-estradiol is able to restore the expression of Bax and Bcl-2 to control levels, but the duration of the treatment is a key factor to obtain the desired effect. These dataprovide new understanding into the mechanisms contributing to the neuroprotective action of estrogen.


Subject(s)
Animals , Rats , Apoptosis , Hippocampus , Ovariectomy , Rats
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