Research into the development of Alzheimer's disease (AD) provides increasing evidence that vascular risk factors, including high serum cholesterol, might influence the progression of cognitive impairment and neural degeneration. In this study, we investigated the effects of high dietary cholesterol intake and the cholesterol-lowering liver X receptor-agonist T0901317 on capillary density, amyloid-β deposition, and presynaptic boutons in the hippocampus of adult (8 months) and aged (15 months) AβPPswe-PS1dE9 and wild-type mice to elucidate how cholesterol may affect neurodegenerative processes in aging and AD. Our results show increased number of presynaptic boutons in 15-month-old AβPP-PS1 mice compared to age-matched wild-type animals, but no difference at 8 months of age. High cholesterol intake accelerated this response by increasing the amount of presynaptic boutons at 8 and 15 months of age, while T0901317 intake decreased the amount of presynaptic boutons in 15-month-old AβPP-PS1 mice. These findings suggest a synaptic compensatory response to maintain connectivity during aging. We hypothesize that high cholesterol intake may cause impaired cerebral blood flow inducing ischemia, fortifying the above mentioned hypothesis of a compensatory mechanism. Contrarily, cholesterol-lowering agents may positively influence cerebral circulation, thereby diminishing aggravation of AD-like pathology.

Brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) are intra-ovarian signalling peptides that are important in follicle development and oocyte maturation. In the ovary, neurotrophin expression is regulated by gonadotrophins. Therefore, this study postulates that aetiology of infertility will affect follicular-fluid BDNF and NGF concentrations. Follicular fluid from the first follicle aspirated from 190 infertile women attending a university-affiliated fertility programme (McMaster University and ONE Fertility, Burlington, Ontario) was collected between February 2004 and November 2010. The relationship between follicular-fluid BDNF and NGF concentration and age, day-3 FSH and peak serum oestradiol concentrations and antral follicle count was determined. Participants were aged between 24 and 44 years (mean±SEM, 35.2±0.3years) of age. The median concentrations of BDNF and NGF in the follicular fluid was 19.4pg/ml and 344.6ng/ml, respectively. The concentrations of BDNF and NGF were significantly related (P=0.028) but only the BDNF concentration was significantly higher (P<0.05) in women with unexplained infertility compared with other causes of infertility. It is concluded that, apart from unexplained infertility, the underlying cause of infertility did not affect ovarian output of BDNF and NGF in response to ovulation induction.