Dexamethasone Does Not Prevent Seven-Day ADX-Induced Apoptosis in the Dentate Gyrus of the Rat Hippocampus

Long-term adrenalectomy (ADX) is known to result in apoptosis within the dentate gyrus of the rat hippocampus. While the underlying mechanism is still unclear, adrenal steroids appear to play a pivotal role in granule cell survival, as administration of the mineralocorticoid receptor (MR) agonists, corticosterone and aldosterone, to ADX rats results in protection against the ADX-induced effect. The consequence of administration of the glucocorticoid receptor (GR) agonists, dexamethasone and RU28362, however, is less clear, and either complete or only partial protection for the ADX animal has been reported. This study investigated further the role played by GR in the degenerative process. After establishing the characteristics of seven-day ADX-induced apoptosis in the young male Wistar rat, the effect of chronically-implanted, subcutaneous pellets containing various doses of dexamethasone and corticosterone, on ADX-induced apoptosis was studied. Both high and low doses of corticosterone were found to be protective. In contrast to some other studies, however, neither dose of dexamethasone had any obvious protective effect and rather seemed to increase apoptosis in dentate gyrus of intact animals. Intracerebroventricular infusion of dexamethasone for seven days was also found to be ineffective in preventing apoptosis, demonstrating that it is occupation of MR, rather than GR, which is crucial to dentate gyrus granule cell survival.     

Increasing calcium intake in young women through gain-framed,targeted messages: A randomised controlled trial

Background: Adequate calcium consumption during early adulthood can help prevent osteoporosis in women.

Purpose: The effects of gain-framed, targeted messaging on calcium intake were examined over 12 months.

Methods: Young women (18–19 years) not consuming sufficient calcium were randomly assigned to receive standard care materials (control) or gain-framed, targeted materials (experimental). Health belief model (HBM) constructs, calcium intake and markers of bone formation, resorption and bone mineral density were assessed at various time points throughout the year.

Results: Calcium intake increased significantly more in the experimental versus the control condition (p?<?0.01). Self-efficacy was the only HBM construct to improve significantly more in the experimental condition versus control (p?=?0.05). The HBM did not mediate changes in calcium intake. Measures of bone health did not differ between conditions by the end of this nonpharmacological intervention (p's?>?0.05).

Conclusions: It is possible to increase young women's calcium consumption through gain-framed, targeted messages.