Florey Department of Neuroscience and Mental Health - Research Publications

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    The Effects of Ethinylestradiol and Progestins ("the pill") on Cognitive Function in Pre-menopausal Women
    Gogos, A ; Wu, YC ; Williams, AS ; Byrne, LK (SPRINGER/PLENUM PUBLISHERS, 2014-12)
    Oral contraceptives (OCs), often referred to as "the pill", are the most commonly employed form of reversible contraception. OCs are comprised of combined synthetic estrogen and progestin, which work to suppress ovulation and subsequently protect against pregnancy. To date, almost 200 million women have taken various formulations of OC, making it one of the most widely consumed classes of medication in the world. While a substantial body of literature has been dedicated to understanding the physical effects of OCs, much less is known about the long term consequences of OC use on brain anatomy and the associated cognitive effects. Accumulating evidence suggests that sex hormones may significantly affect human cognition. This phenomenon has been commonly studied in older populations, such as in post-menopausal women, while research in healthy, pre-menopausal women remains limited. The current review focused on the effects of OCs on human cognition, with the majority of studies comparing pre-menopausal OC users to naturally cycling women. Human neuroimaging data and animal studies are also described herein. Taken together, the published findings on OC use and human cognition are varied. Of those that do report positive results, OC users appear to have improved verbal memory, associative learning and spatial attention. We recommend future research to employ blinding procedures and randomised designs. Further, more detailed information pertaining to the specific generation and phasic type of OCs, as well as menstrual cycle phase of the OC non-users should be considered to help unmask the potential impact of OC use on human cognition.
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    Sex-dependent alterations in BDNF-TrkB signaling in the hippocampus of reelin heterozygous mice: a role for sex steroid hormones
    Hill, RA ; Wu, Y-WC ; Gogos, A ; van den Buuse, M (WILEY, 2013-08)
    Neurodevelopmental psychiatric disorders such as schizophrenia may be caused by a combination of gene × environment, gene × gene, and/or gene × sex interactions. Reduced expression of both Reelin and Brain-Derived Neurotrophic factor (BDNF) has been associated with schizophrenia in human post-mortem studies. However, it remains unclear how Reelin and BDNF interact (gene × gene) and whether this is sex-specific (gene × sex). This study investigated BDNF-TrkB signaling in the hippocampus of male and female Reelin heterozygous (Rln(+/-) ) mice. We found significantly increased levels of BDNF in the ventral hippocampus (VHP) of female, but not male Rln(+/-) compared to wild-type (WT) controls. While levels of TrkB were not significantly altered, phosphorylated TrkB (pTrkB) levels were significantly lower, again only in female Rln(+/-) compared to WT. This translated to downstream effects with a significant decrease in phosphorylated ERK1 (pERK1). No changes in BDNF, TrkB, pTrkB or pERK1/2 were observed in the dorsal hippocampus of Rln(+/-) mice. Ovariectomy (OVX) had no effect in WT controls, but caused a significant decrease in BDNF expression in the VHP of Rln(+/-) mice to the levels of intact WT controls. The high expression of BDNF was restored in OVX Rln(+/-) mice by 17β-estradiol treatment, suggesting that Rln(+/-) mice respond differently to an altered estradiol state than WT controls. In addition, while OVX had no significant effect on TrkB or ERK expression/phosphorylation, OVX + estradiol treatment markedly increased TrkB and ERK1 phosphorylation in Rln(+/-) and, to a lesser extent in WT controls, compared to intact genotype-matched controls. These data may provide a better understanding of the interaction of Reelin and BDNF in the hippocampus, which may be involved in schizophrenia.