Generation Scotland: the Scottish Family Health Study aims to identify genetic variants accounting for variation in levels of quantitative traits underlying the major common complex diseases (such as ...cardiovascular disease, cognitive decline, mental illness) in Scotland.
Generation Scotland will recruit a family-based cohort of up to 50,000 individuals (comprising siblings and parent-offspring groups) across Scotland. It will be a six-year programme, beginning in Glasgow and Tayside in the first two years (Phase 1) before extending to other parts of Scotland in the remaining four years (Phase 2). In Phase 1, individuals aged between 35 and 55 years, living in the East and West of Scotland will be invited to participate, along with at least one (and preferably more) siblings and any other first degree relatives aged 18 or over. The total initial sample size will be 15,000 and it is planned that this will increase to 50,000 in Phase 2. All participants will be asked to contribute blood samples from which DNA will be extracted and stored for future investigation. The information from the DNA, along with answers to a life-style and medical history questionnaire, clinical and biochemical measurements taken at the time of donation, and subsequent health developments over the life course (traced through electronic health records) will be stored and used for research purposes. In addition, a detailed public consultation process will begin that will allow respondents' views to shape and develop the study. This is an important aspect to the research, and forms the continuation of a long-term parallel engagement process.
As well as gene identification, the family-based study design will allow measurement of the heritability and familial aggregation of relevant quantitative traits, and the study of how genetic effects may vary by parent-of-origin. Long-term potential outcomes of this research include the targeting of disease prevention and treatment, and the development of screening tools based on the new genetic information. This study approach is complementary to other population-based genetic epidemiology studies, such as UK Biobank, which are established primarily to characterise genes and genetic risk in the population.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
We have studied synaptic function in a transgenic mouse strain relevant to Alzheimer's disease (AD), overexpressing the 695 amino acid isoform of human amyloid precursor protein with K670N and M671L ...mutations (APP(695)SWE mice), which is associated with early-onset familial AD. Aged-transgenic mice had substantially elevated levels of Abeta (up to 22 micromol/gm) and displayed characteristic Abeta plaques. Hippocampal slices from 12-month-old APP(695)SWE transgenic animals displayed reduced levels of synaptic transmission in the CA1 region when compared with wild-type littermate controls. Inclusion of the ionotropic glutamate receptor antagonist kynurenate during preparation of brain slices abolished this deficit. At 18 months of age, a selective deficit in basal synaptic transmission was observed in the CA1 region despite treatment with kynurenate. Paired-pulse facilitation and long-term potentiation (LTP) were normal in APP(695)SWE transgenic mice at both 12 and 18 months of age. Thus, although aged APP(695)SWE transgenic mice have greatly elevated levels of Abeta protein, increased numbers of plaques, and reduced basal synaptic transmission, LTP can still be induced and expressed normally. We conclude that increased susceptibility to excitotoxicity rather than a specific effect on LTP is the primary cause of cognitive deficits in APP(695)SWE mice.
Synaptic transmission and long-term potentiation (LTP) in the CA1 region of hippocampal slices have been studied during ageing of a double transgenic mouse strain relevant to early-onset familial ...Alzheimer's disease (AD). This strain, which over-expresses both the 695 amino acid isoform of human amyloid precursor protein (APP) with K670N and M671L mutations and presenilin 1 with the A246E mutation, has accelerated amyloidosis and plaque formation. There was a decrease in synaptic transmission in both wildtype and transgenic mice between 2 and 9 months of age. However, preparing slices from 14 month old animals in kynurenic acid (1 mM) counteracted this age-related deficit. Basal transmission and paired-pulse facilitation was similar between the two groups at all ages (2, 6, 9 and 14 months) tested. Similarly, at all ages LTP, induced either by theta burst stimulation or by multiple tetani, was normal. These data show that a prolonged, substantially elevated level of Abeta are not sufficient to cause deficits in the induction or expression of LTP in the CA1 hippocampal region.
GS:SFHS is a family-based genetic epidemiology study with DNA and socio-demographic and clinical data from about 24 000 volunteers across Scotland aged 18-98 years, from February 2006 to March 2011. ...Biological samples and anonymized data form a resource for research on the genetics of health, disease and quantitative traits of current and projected public health importance. Specific and important features of GS:SFHS include the family-based recruitment, with the intent of obtaining family groups; the breadth and depth of phenotype information, including detailed data on cognitive function, personality traits and mental health; consent and mechanisms for linkage of all data to comprehensive routine health-care records; and 'broad' consent from participants to use their data and samples for a wide range of medical research, including commercial research, and for re-contact for the potential collection of other data or samples, or for participation in related studies and the design and review of the protocol in parallel with in-depth sociological research on (potential) participants and users of the research outcomes. These features were designed to maximize the power of the resource to identify, replicate or control for genetic factors associated with a wide spectrum of illnesses and risk factors, both now and in the future.
Sucrose-based artificial cerebrospinal fluid (aCSF) is sometimes used to prepare brain slices for in vitro electrophysiological experiments. This study compared the effect of preparing brain slices ...using chilled sucrose-based aCSF versus the conventional method using chilled aCSF on hippocampal synaptic plasticity. Brain slices from each treatment group were transferred to normal aCSF before electrophysiological recordings were made. The stimulus–response relationship of field excitatory postsynaptic potentials (fEPSPs) in the CA1 region was indistinguishable between the two treatment groups. However, the amount of LTP induced by either a θ-burst (four stimuli at 100 Hz repeated ten times at 200 ms intervals) or tetanic stimulation (100 Hz for 1 s) was significantly reduced in slices that had been prepared using sucrose-based aCSF. This was associated with reduced facilitation of the fEPSPs during the high frequency stimulus, reduced post-tetanic potentiation and short-term potentiation. In sucrose-cut slices the fEPSPs were slightly shorter in duration (29%,
P<0.01), and during paired-pulse stimulation the broadening of the second fEPSP was enhanced. The LTP deficit in sucrose-cut slices was reversed by blocking GABA
A receptor function with picrotoxin. These data suggest that the use of sucrose based aCSF better preserves GABA-mediated synaptic transmission, which limits the induction of LTP in hippocampal brain slices.
Although mutations in amyloid precursor protein (APP) are known to be involved in the development of Alzheimer's disease in some individuals, the role of this protein in normal brain function is ...poorly understood. We have reported previously that in APP-null mice long-term potentiation (LTP) in the CA1 region of the hippocampus is present but its magnitude is reduced compared to wild-type littermate controls. In the present study, we have confirmed this deficit using a different theta burst induction protocol. Significantly, however, we find that this deficit is no longer apparent when LTP experiments are performed following blockade of γ-aminobutyric acid
A receptors. These results suggest that the LTP process per se is not altered by the absence of APP. The deficit may therefore be an indirect consequence of other changes in the hippocampus that occur in the APP-null animal.
Cyclic GMP (cGMP) has been implicated in the modulation of long-term potentiation (LTP) and depression (LTD) in the hippocampus. Transcripts for subunits of several types of cGMP specific ...phosphodiesterase are found in the mammalian brain but their relative role in hippocampal function is unclear. The retinal degeneration (
rd) mutation in the gene encoding the PDE6B subunit causes a loss of function in PDE6 enzyme and in adult mice homozygous to the mutation it causes blindness. We have used this natural mutation, and the cGMP phosphodiesterase inhibitor zaprinast, in wild-type and
rd/
rd mouse littermates to investigate whether PDE5 and/or PDE6 regulates excitatory synaptic transmission in the hippocampus. Mice were genotyped using two independent PCR methods. Glutamate-mediated synaptic transmission in the CA1 region or dentate gyrus was unaffected in hippocampal brain slices from mice carrying the
rd mutation. Similarly the facilitation of synaptic events by paired-pulse stimuli, and LTP induced by a theta-burst (10 bursts of four events at 100 Hz with a 200-ms inter-burst interval) were normal in
rd/
rd mice. Inhibition of cGMP-specific PDE activity by zaprinast (10 μM, an inhibitor of PDE5 and PDE6) induced a slowly developing and sustained depression of field synaptic potentials that was quantitatively similar in both wild-type and
rd/
rd mice. Thus in the CA1 region synaptic plasticity is likely to be regulated by the PDE5 rather than the PDE6 isoform.
Presenilin-1 (PS1) is intimately involved in cleavage of amyloid precursor protein to form β-amyloid peptides, certain forms of which aggregate in the brains of patients with Alzheimer's disease ...(AD). The function(s) of PS1 and its precise involvement in the development of cognitive deficits associated with AD are unclear. We have utilised genetically modified mice that under-express PS1 (PS1
+/− mice) to investigate the role of PS1 in hippocampal synaptic plasticity. Field excitatory postsynaptic responses elicited by baseline stimulation were indistinguishable between PS1
+/− mice and wild-type controls. Likewise, a measure of short-term plasticity, paired-pulse facilitation, was normal in PS1
+/− mice. However, long-term potentiation induced by multiple tetanus trains was reduced in PS1
+/− animals. These results demonstrate that chronic reduction of PS1 activity leads to impaired synaptic plasticity, thus suggesting a role for PS1 in normal cognitive function.
1. Intracellular current clamp recordings were made from CA1 pyramidal neurones in rat hippocampal slices. Experiments were
performed in the presence of ionotropic glutamate receptor antagonists and ...gamma-aminobutyric acid (GABA) receptor antagonists
to block all fast excitatory and inhibitory synaptic transmission. A single stimulus, delivered extracellularly in the stratum
oriens, caused a reduction in spike frequency adaptation in response to a depolarizing current step delivered 2 s after the
stimulus. A 2- to 10-fold increase in stimulus intensity evoked a slow excitatory postsynaptic potential (EPSP) which was
associated with a small increase in input resistance. The peak amplitude of the EPSP occurred approximately 2.5 s after the
stimulus and its magnitude (up to 30 mV) and duration (10-50 s) increased with increasing stimulus intensity. 2. The slow
EPSP was unaffected by the metabotropic glutamate receptor antagonist (+)-alpha-methyl-4-carboxyphenylglycine ((+)-MCPG; 1000
microM) but was greatly enhanced by the acetylcholinesterase inhibitor physostigmine (1-5 microM). Both the slow EPSP and
the stimulus-evoked reduction in spike frequency adaptation were inhibited by the muscarinic acetylcholine receptor (mAChR)
antagonist atropine (1-5 microM). These results are consistent with these effects being mediated by mAChRs. 3. Both the mAChR-mediated
EPSP (EPSPm) and the associated reduction in spike frequency adaptation were reversibly depressed (up to 97%) by either adenosine
(100 microM) or its non-hydrolysable analogue 2-chloroadenosine (CADO; 0.1-5.0 microM). These effects were often accompanied
by postsynaptic hyperpolarization (up to 8 mV) and a reduction in input resistance (up to 11%). The selective adenosine A1
receptor agonists 2-chloro-N6-cyclopentyladenosine (CCPA; 0.1-0.4 microM) and R(-)N6-(2-phenylisopropyl)-adenosine (R-PIA;
1 microM) both depressed the EPSPm. In contrast, the adenosine A2A receptor agonist 2-p-(2-carboxyethyl)-phenethylamino-5'-N-ethylcarboxamidoadenosine
(CGS 21680; 0.5-1.0 microM) did not significantly affect the EPSPm. 4. The selective adenosine A1 receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine
(DPCPX; 0.2 microM) fully reversed the depressant effects of both adenosine (100 microM) and CADO (1 microM) on the EPSPm
and the stimulus-evoked reductions in spike frequency adaptation. 5. DPCPX (0.2 microM) alone caused a small but variable
mean increase in the EPSPm of 22 +/- 19% and enabled activation of an EPSPm by a previously subthreshold stimulus. In contrast,
the selective adenosine kinase inhibitor 5-iodotubercidin (5-IT; 10 microM) inhibited the EPSPm by 74 +/- 10%, an effect that
was reversed by DPCPX. 6. The concentration-response relationship for the depressant action of CADO on the EPSPm more closely
paralleled that for its presynaptic depressant action on glutamate-mediated EPSPs than that for postsynaptic hyperpolarization.
The respective mean IC50 and EC50 concentrations for these effects were 0.3, 0.8 and 3.0 microM. 7. CADO (1-5 microM) did
not have a significant effect on the postsynaptic depolarization, increase in input resistance and reduction in spike frequency
adaptation evoked by carbachol (0.5-3.0 microM). All these effects were abolished by atropine (1 microM). 8. These data provide
good evidence for an adenosine A1 receptor-mediated inhibition of mAChR-mediated synaptic responses in hippocampal CA1 pyramidal
neurones. This inhibition is mediated predominantly presynaptically, is active tonically and can be enhanced when extracellular
levels of endogenous adenosine are raised.
Both GABA B and muscarinic acetylcholine receptors (mAChRs) influence hippocampal-dependent mnemonic processing. Here the possibility
of a direct interaction between GABA B receptors and ...mAChR-mediated synaptic responses has been studied using intracellular recording in rat hippocampal slices.
The GABA B receptor agonist(â)-baclofen (5â10 μ m ) depressed an atropine-sensitive slow EPSP (EPSP M ) and occluded the GABA B -receptor-mediated IPSP (IPSP B ) which preceded it. These inhibitory effects were accompanied by postsynaptic hyperpolarization (9 ± 2 mV) and a reduction
in cell input resistance (12 ± 3 %).
The selective GABA B receptor antagonist CGP 55845A (1 μ m ) fully reversed the depressant effects of (â)-baclofen (5â10 μ m ) such that in the combined presence of (â)-baclofen and CGP 55845A the EPSP M was 134 ± 21 % of control.
(â)-Baclofen (5â10 μ m ) caused a small (28 ± 11 %) inhibition of carbachol-induced (3.0 μ m ) postsynaptic depolarizations and increases in input resistance.
CGP 55845A (1 μ m ) alone caused an increase in the amplitude of the EPSP M (253 ± 74 % of control) and blocked the IPSP B that preceded it.
In contrast, the selective GABA uptake inhibitor NNC 05â0711 (10 μ m ) increased the amplitude of the IPSP B by 141 ± 38 % and depressed the amplitude of the EPSP M by 58 ± 10 %. This inhibition was abolished by CGP 55845A (1 μ m ).
Taken together these data provide good evidence that synaptically released GABA activates GABA B receptors that inhibit mAChR-mediated EPSPs in hippocampal CA1 pyramidal neurones. The mechanism of inhibition may involve
both pre- and postsynaptic elements.
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