Joanne Ryan

Postnatal stability, tissue, and time specific effects of AHRR methylation change in response to maternal smoking in pregnancy

The intrauterine environment has the potential to “program” the developing fetus in a way that can be potentially deleterious to later health. While in utero environmental/stochastic factors are known to influence DNA methylation profile at birth, it has been difficult to assign specific examples of epigenetic variation to specific environmental exposures. Recently, several studies have linked exposure to smoking with DNA methylation change in the aryl hydrocarbon receptor repressor (AHRR) gene in blood. This includes hypomethylation of AHRR in neonatal blood in response to maternal smoking in pregnancy. The role of AHRR as a negative regulator of pathways involved in pleiotropic responses to environmental contaminants raises the possibility that smoking-induced hypomethylation is an adaptive response to an adverse in utero environmental exposure. However, the tissue specificity of the response to maternal smoking, and the stability of the methylation changes early in life remain to be determined. In this study we analyzed AHRR methylation in three cell types—cord blood mononuclear cells (CBMCs), buccal epithelium, and placenta tissue—from newborn twins of mothers who smoked throughout pregnancy and matched controls. Further, we explored the postnatal stability of this change at 18 months. Our results confirm the previous association between maternal smoking and AHRR methylation in neonatal blood. In addition, this study expands the region of AHRR methylation altered in response to maternal smoking during pregnancy and reveals the tissue-specific nature of epigenetic responses to environmental exposures in utero. Further, the evidence for postnatal stability of smoking-induced epigenetic change supports a role for epigenetics as a mediator of long-term effects of specific in utero exposures in humans. Longitudinal analysis of further specific exposures in larger cohorts is required to examine the extent of this phenomenon in humans.

Late-life depression and mortality: influence of gender and antidepressant use

BACKGROUND Depression may increase the risk of mortality among certain subgroups of older people, but the part played by antidepressants in this association has not been thoroughly explored. AIMS To identify the characteristics of older populations who are most at risk of dying, as a function of depressive symptoms, gender and antidepressant use. METHOD Adjusted Cox proportional hazards models were used to determine the association between depression and/or antidepressant use and 4-year survival of 7,363 community-dwelling elderly people. Major depressive disorder was evaluated using a standardised psychiatric examination based on DSM-IV criteria and depressive symptoms were assessed using the Center for Epidemiological Studies-Depression scale. RESULTS Depressed men using antidepressants had the greatest risk of dying, with increasing depression severity corresponding to a higher hazard risk. Among women, only severe depression in the absence of treatment was significantly associated with mortality. CONCLUSIONS The association between depression and mortality is gender-dependent and varies according to symptom load and antidepressant use.

A prospective study of the association between endogenous hormones and depressive symptoms in postmenopausal women.

Objective: Across a womans lifetime, variations in hormone levels are known to influence mood and well-being. Whether absolute or changes in hormone levels over time are associated with depression among postmenopausal women remains unclear. Methods: The Melbourne Womens Midlife Health Project is a longitudinal population-based study of women who were followed through the menopausal transition. This analysis is based on data collected from 138 postmenopausal women in years 11 and 13 of the study, who were assessed for the presence of depressive symptoms using the Center for Epidemiological Studies Depression Scale. Logistic regression models were developed to determine whether absolute or changes in hormone levels were associated with depression. Results: No significant associations were found between depressive symptoms and the absolute levels of sex hormone-binding globulin, testosterone, free androgen index, estradiol, free estradiol, or follicle-stimulating hormone (FSH). On the other hand, women with a decline in total serum estradiol over the 2-year period had a more than threefold increased risk of depressive symptoms (odds ratio, 3.5; 95% CI, 1.2-9.9). A large increase in FSH levels over this period was also associated with depressive symptoms (odds ratio, 2.6; 95% CI, 1.0-6.7). These associations remained even after adjustment for initial depression score, as well as a range of potential confounding factors. Conclusions: Changes in estradiol and, to a lesser extent, in FSH levels are associated with an increased risk of depressive symptoms in postmenopausal women. These results further support a role for fluctuating rather than absolute hormone levels in depression in later life.

New trisubstituted 1,2,4-triazole derivatives as potent ghrelin receptor antagonists. 3. Synthesis and pharmacological in vitro and in vivo evaluations.

Ghrelin receptor ligands based on trisubstituted 1,2,4-triazole structure were synthesized and evaluated for their in vitro binding and biological activity. In this study, we explored the replacement of the alpha-aminoisobutyryl moiety by aromatic or heteroaromatic groups. Compounds 5 and 34 acted as potent in vivo antagonists of hexarelin-stimulated food intake. These two compounds did not stimulate growth hormone secretion in rodents and did not antagonize growth hormone secretion induced by hexarelin.

The Wnt Target Jagged-1 Mediates the Activation of Notch Signaling by Progastrin in Human Colorectal Cancer Cells

The Wnt and Notch signaling pathways are both abnormally activated in colorectal cancer (CRC). We recently showed that progastrin depletion inhibited Wnt signaling and increased goblet cell differentiation of CRC cells. Here, we show that progastrin down-regulation restores the expression by CRC cells of the early secretory lineage marker Math-1/Hath-1 due to an inhibition of Notch signaling. This effect is mediated by a decreased transcription of the Notch ligand Jagged-1, downstream of beta-catenin/Tcf-4. Accordingly, recombinant progastrin sequentially activated the transcription of Wnt and Notch target genes in progastrin-depleted cells. In addition, restoration of Jagged-1 levels in these cells is sufficient to activate Tcf-4 activity, demonstrating the occurrence of a feedback regulation from Notch toward Wnt signaling. These results suggest that progastrin could be instrumental in maintaining the concomitant activation of Wnt and Notch pathways in CRC cells, further highlighting the interest of progastrin targeting for the clinical management of CRC.

Hormonal treatment, mild cognitive impairment and Alzheimer's disease.

A plethora of in vitro and in vivo studies have supported the neuroprotective role of estrogens and their impact on the neurotransmitter systems implicated in cognition. Recent hormonal replacement therapy (HRT) trials in non-demented postmenopausal women suggest a temporary positive effect (notably on verbal memory), and four meta-analyses converge to suggest a possible protective effect in relation to Alzheimers disease (reducing risk by 29 to 44%). However, data from the only large randomized controlled trial published to date, the Womens Health Initiative Memory Study, did not confirm these observations and have even suggested an increase in dementia risk for women using HRT compared to controls. Apart from methodological differences, one key shortcoming of this trial has probably been the focus on late-onset (postmenopausal) hormonal changes, i.e. at a time when the neurodegenerative process has already begun and without taking into account individual lifetime exposure to hormone variability. Multifactorial models based on an exhaustive view of all hormonal events throughout the reproductive life (rather than on a specific exposure to a given steroid) together with other risk factors (notably genetic risk factors related to estrogen receptor polymorphisms) should be explored to clarify the role of hormonal risk factors, or protective factors for cognitive dysfunction and dementia.

Characteristics of hormone therapy, cognitive function, and dementia: the prospective 3C Study

Objectives: To examine the association between hormone therapy (HT) and cognitive performance or dementia, focusing on the duration and type of treatment used, as well as the timing of initiation of HT in relation to the menopause. Methods: Women 65 years and older were recruited in France as part of the Three City Study. At baseline and 2- and 4-year follow-up, women were administered a short cognitive test battery and a clinical diagnosis of dementia was made. Detailed information was also gathered relating to current and past HT use. Analysis was adjusted for a number of sociodemographic, behavioral, physical, and mental health variables, as well as APOE ε4. Results: Among 3,130 naturally postmenopausal women, current HT users performed significantly better than never users on verbal fluency, working memory, and psychomotor speed. These associations varied according to the type of treatment and a longer duration of HT appeared to be more beneficial. However, initiation of HT close to the menopause was not associated with better cognition. HT did not significantly reduce dementia risk over 4 years but current treatment diminished the negative effect associated with APOE ε4. Conclusions: Current hormone therapy (HT) was associated with better performance in certain cognitive domains but these associations are dependent on the duration and type of treatment used. We found no evidence that HT needs to be initiated close to the menopause to have a beneficial effect on cognitive function in later life. Current HT may decrease the risk of dementia associated with the APOE ε4 allele.

Recent developments in ghrelin receptor ligands.

The 28‐amino acid peptide ghrelin is a neuroendocrine hormone synthesized primarily in the stomach. It stimulates growth hormone secretion and appetite, thus promoting food intake and body‐weight gain. The pharmacological properties of this peptide are mediated by the growth hormone secretagogue receptor type 1a (GHS‐R1a). Given its wide spectrum of biological activities, it is evident that the discovery of ghrelin and its receptor has opened up many perspectives in the fields of neuroendocrine and metabolic research and has had an influence on such fields of internal medicine as gastroenterology, oncology, and cardiology. It is therefore increasingly likely that synthetic, peptidyl, and nonpeptidyl GHS‐R1a ligands, acting as agonists, partial agonists, antagonists, or inverse agonists, could have both clinical and therapeutic potential. This review summarizes the various types of GHS‐R1a ligands that have been described in the literature and discusses the recent progress made in this research area.

Life-time estrogen exposure and cognitive functioning in later life

CONTEXT While recent studies suggest that exogenous estrogen treatment could help reduce age-related cognitive decline and delay the onset of dementia, this has not been found consistently. Few studies have considered the influence of life-time estrogen exposure which may have an independent effect on cognition and/or modulate treatment response. OBJECTIVE The aim of this study was to examine whether factors related to estrogen exposure across the life-time were associated with cognitive function in postmenopausal women. DESIGN A battery of cognitive tests were administered at baseline and at 2 and 4 years of follow-up to evaluate cognitive performance among a population-based cohort of 996 French women aged 65 years or older, who were recruited as part of the ESPRIT study. Detailed reproductive histories were also obtained. Logistic regression models, controlling for an extensive range of potential confounding factors, were generated to determine whether hormone-related factors across a womans lifetime were associated with poor cognitive performance in later life. RESULTS Age at first menses was negatively associated with performance on the tasks of visual memory and psychomotor speed, while a longer reproductive period was associated with better verbal fluency. Likewise, women who had their first child at a young age performed significantly worse on each of these tasks, as well as on a measure of global cognitive function. The results also suggest that current hormone therapy may be beneficial for a number of cognitive domains, however, in multivariate analysis, women performed significantly better on the task of visual memory only. In contrast, in analysis adjusted for baseline cognitive performance and a range of other factors, none of the reproductive variables were associated with a decline in cognitive performance or the incidence of dementia during the 4-year follow-up period. CONCLUSIONS In addition to hormone therapy, certain hormone-related events across the lifetime are also associated with cognitive functioning in later life. They were not observed in this study to modulate dementia risk; however, this should be verified over a longer follow-up period. Further studies will also be required to determine whether lifetime hormonal exposure may modify womens response to hormone therapy after the menopause.

Hormone levels and cognitive function in postmenopausal midlife women

Gonadal hormones may influence cognitive function. Postmenopausal midlife women in the population-based Melbourne Womens Midlife Health Project cohort were administered a comprehensive battery of neuropsychological tests on two occasions 2 years apart. Participants (n = 148, mean age 60 years) had undergone natural menopause and were not using hormone therapy. Estrone, total and free estradiol, and total and free testosterone levels were measured at time of the first testing. Principal-component analysis identified four cognitive factors. In multiple linear regression analyses, better semantic memory performance was associated with higher total (p = 0.02) and free (p = 0.03) estradiol levels and a lower ratio of testosterone to estradiol (p = 0.007). There were trends for associations between better verbal episodic memory and lower total testosterone (p = 0.08) and lower testosterone/estradiol ratio (p = 0.06). Lower free testosterone levels were associated with greater 2-year improvement on verbal episodic memory (p = 0.04); higher testosterone/estradiol predicted greater semantic memory improvement (p = 0.03). In postmenopausal midlife women, endogenous estradiol and testosterone levels and the testosterone/estradiol ratio are associated with semantic memory and verbal episodic memory abilities.