Effects of estrogen on intracellular signaling pathways linked to activation of muscarinic acetylcholine receptors and on acetylcholinesterase activity in rat hippocampus

Effects of 17β-estradiol replacement on the apoptotic effects caused by ovariectomy in the rat hippocampus

“…There is evidence in the literature to support the hypothesis that estrogen may lose its ability to positively affect cognition after a longterm period of hormone deprivation in female rats (Gibbs 2000;Cardoso et al 2004;Daniel et al 2006;Pereira et al 2008). However, in the present study, the neuroprotective effects of a physiological dose of 17β-estradiol was clearly demonstrated not only if the treatment with the hormone was initiated immediately after ovariectomy but also if the treatment started after a period of hormonal deprivation.…”

“…The last injection of 17β-estradiol (17β-estradiol benzoate, Sigma Chemical Co., MO, USA) was given one day before euthanasia. A dose of 50 µg/kg of 17β-estradiol was chosen because it results in circulating levels of estradiol observed on the morning of proestrus (Viau and Meaney 1991), has been shown to maintain the relative weight of the uterus (Cardoso et al 2004;Pereira et al 2008) and to enhance cell proliferation in the dentate gyrus of adult female rats (Tanapat et al 2005;Barha et al 2009). However, this same dose produces supraphysiological levels of estradiol shortly after administration (Woolley and McEwen 1993), stabilize to physiological range and then decay to control levels over the next 24 to 48 hours (Gibbs 1997(Gibbs , 1998(Gibbs , 2000.…”

“…However, this same dose produces supraphysiological levels of estradiol shortly after administration (Woolley and McEwen 1993), stabilize to physiological range and then decay to control levels over the next 24 to 48 hours (Gibbs 1997(Gibbs , 1998(Gibbs , 2000. All experimental groups were chosen based on previous studies (Gibbs 1997(Gibbs , 1998(Gibbs , 2000Cardoso et al 2004;Pereira et al 2008).…”

17-β estradiol in the acetylcholinesterase activity and lipid peroxidation in the brain and blood of ovariectomized adult and middle-aged rats

“…The duration and/or the critical period of initiation of estrogen therapy should be considered important for an influence on the brain AChE activity (Pereira et al, 2008). Another important aspect is that HP and CC, which receive cholinergic projections from the nucleus basalis of Meynert and ST (which has an intrinsic cholinergic circuit), did not present similar results in our research.…”

Water quality evaluation of two interconnected dam lakes with field-captured and laboratory-acclimated fish, Cyprinus carpio

“…There is limited literature on E 2 exposure and AChE activity correlation on fish. Pereira et al (2008) suggested that estrogen modulates muscarinic acetylcholine receptor expression and AChE activity in rat brain. On the other hand, an analysis of fish exposed to a synthetic pharmaceutical estrogen, ethynylestradiol, for 3 and 7 days indicated enhanced AChE activity (Greco et al 2007).…”