Tamoxifen and raloxifene modulate gap junction coupling during early phases of retinoic acid-dependent neuronal differentiation of NTera2/D1 cells

Gap junctions (GJ) represent a cellular communication system known to influence neuronal differentiation and survival. To assess a putative role of this system for neural effects of tamoxifen (TAM) and raloxifene (RAL), we used the human teratocarcinoma cell line NTera2/D1, retinoic acid (RA)-dependent neuronal differentiation of which is regulated by gap junctions formed of connexin43 (Cx43). As demonstrated by Western blot analysis, concentrations above 1 µmol/l for TAM, and 0.1 µmol/l for RAL lead to a temporary time- and concentration-dependent increase in Cx43 immunoreactivity, which reached a peak for TAM after 1 day and for RAL after 2 days. Immunocytochemical stainings revealed the increase in Cx43 immunoreactivity to result from an accumulation in intracellular compartments such as the Golgi apparatus or lysosomes. In addition, TAM and RAL were able to prevent the RA-dependent decrease of Cx43 immunoreactivity in NTera2/D1 cells, normally observed during neuronal differentiation. This suggested a suppression of neuronal differentiation to result from these substances. According to this, treatment of NTera2/D1 cells with 10 µmol/l TAM or RAL during weeks 1 and 2 of a 6 weeks RA-driven differentiation schedule impaired, whereas treatment during weeks 5 and 6 did not impair, neuronal differentiation of these cells. Modulation of GJ coupling between NTera2/D1 cells by TAM and RAL seems therefore to perturb early neuronal differentiation, whereas differentiated neurons in the mature brain seem to be not affected. These effects could be of importance for actions of TAM and RAL on early embryonic steps of nervous system formation

Assessing physical activity in older people: findings from the Hertfordshire cohort study

Background: Physical activity (PA) is difficult to assess and few instruments are relevant to older people. We have developed a self-administered PA questionnaire (HPAQ) for the Hertfordshire Cohort Study; we report its feasibility and validity and describe PA participation in older people.Methods: 525 participants completed the HPAQ; 15 women also completed the EPAQ-2 for validation. Activity participation was described using percentage participation, estimated energy expenditure and cluster analysis.Results: Most participants found the HPAQ simple to complete. Agreement between the HPAQ and EPAQ-2 was good. Activities with highest participation rates and energy expenditures were walking (99.6%, 149.8 MET.h/mth) for men and home activities (100%, 287.1 MET.h/mth) for women. Clustering identified three patterns of activity participation for men (“Keep Fit”, “Indoors” & “Less active”), and two for women (“Keep Fit” & “Indoors”).Conclusions: The HPAQ is a feasible and valid PA questionnaire for older people. Clustering identified different patterns of PA participation