p(MGI:Chrna7)
Mice with a null mutation in the gene that encodes KAT II became a unique tool to resolve this issue (31, 410, 516). Low levels of KYNA in these mutant mice lead to alpha7 nAChR disinhibition in hippocampal CA1 SR interneurons, thereby increasing the activity of GABAergic interneurons impinging onto CA1 pyramidal neurons (31) PubMed:19126755
Mouse strains, like humans, also exhibit a striking age-related decline in nAChR expression. For instance, in the hippocampus of aged CBA and B6 mice, expression of alpha4 and alpha7 nAChR subunits decreases with age (166). PubMed:19126755
Tg2576 mice expressing human Abeta show reduced [3H]cytisine binding (a label of nAChRs) in the cortex at 17 months after birth (Apelt et al., 2002). In contrast, however, levels of alpha7 or alpha4 subunits were unchanged in double-mutant Swedish APP/PS-1 mice as determined by radiolabeled cytosine (alpha4beta2) or alpha-bungarotoxin (alpha7) binding (Marutle et al., 2002). PubMed:19293145
However, we identify a possible role of the alpha7 subunit in the normal aging process that should be further investigated PubMed:27522251
The analysis also showed significant effects of PHA and Gal on the protein levels on comparing with normal saline in AD mice (p<0.001). Moreover, Gal could not completely protect the a7 nAChR protein level in AD animals. This group has a lesser a7 nAChR protein level in comparison with the control group (p<0.001) (Fig. 8). The groups showed results in the cortex similar to those observed in the hippocampus (data not shown) PubMed:25881725
Inter-group analysis showed that the protein level decreased by pretreatment with selective a7 nAChR antagonist MLA (p<0.001). PHA and Gal prevent receptor destroying in AD animals, but this effect is completely abolished by MLA (p<0.001) (Fig. 9). The groups showed results in the cortex similar to those observed in the hippocampus (data not shown). PubMed:25881725
The analysis also showed significant effects of PHA and Gal on the protein levels on comparing with normal saline in AD mice (p<0.001). Moreover, Gal could not completely protect the a7 nAChR protein level in AD animals. This group has a lesser a7 nAChR protein level in comparison with the control group (p<0.001) (Fig. 8). The groups showed results in the cortex similar to those observed in the hippocampus (data not shown) PubMed:25881725
Inter-group analysis showed that the protein level decreased by pretreatment with selective a7 nAChR antagonist MLA (p<0.001). PHA and Gal prevent receptor destroying in AD animals, but this effect is completely abolished by MLA (p<0.001) (Fig. 9). The groups showed results in the cortex similar to those observed in the hippocampus (data not shown). PubMed:25881725
Notably, PHA could completely block the Ab-impaired task acquisition and reduce escape-latency to the normal level. Furthermore, the effect of PHA against the Ab-impaired task acquisition could be abolished by the pre-treatment of the a7 nAChR antagonist MLA (p<0.001). It was also noted that blockade of a7 nAChR by MLA in the Gal-treated group resulted in a significant prolongation of the escape-latency on comparing with the Gal group (p<0.001) (Fig. 2). PubMed:25881725
Effect of a7 nAChRs blockage on time spent in target quadrant in probe trials. The implications of the a7 nAChRs on PHA- or Gal-induced spatial memory enhancement were investigated by pretreatment with normal saline or MLA. A two-way ANOVA revealed significant differences of treatment [F(1,56)=4.24, p<0.05], pretreatment [F(1,56)=96.87, p<0.001] and treatment pretreatment interaction [F(1,32)=10.69, p<0.01]. Inter-group analysis showed that this effect was blocked by the selective a7 nAChR antagonist MLA (p<0.001). PubMed:25881725
Inter-group analysis showed that the protein level decreased by pretreatment with selective a7 nAChR antagonist MLA (p<0.001). PHA and Gal prevent receptor destroying in AD animals, but this effect is completely abolished by MLA (p<0.001) (Fig. 9). The groups showed results in the cortex similar to those observed in the hippocampus (data not shown). PubMed:25881725
Post hoc analysis revealed that, levels of the a7 nAChR protein in normal saline-treated AD mice were significantly lower than its level in the control animals (p<0.001). PubMed:25881725
α7 nAChRs are essential for the plasticity of the airway epithelium as α7 Ko mice show altered basal cell layer formation, hyperplasia, and uncontrolled growth PubMed:28901280
Mice with a null mutation in the gene that encodes KAT II became a unique tool to resolve this issue (31, 410, 516). Low levels of KYNA in these mutant mice lead to alpha7 nAChR disinhibition in hippocampal CA1 SR interneurons, thereby increasing the activity of GABAergic interneurons impinging onto CA1 pyramidal neurons (31) PubMed:19126755
Mouse strains, like humans, also exhibit a striking age-related decline in nAChR expression. For instance, in the hippocampus of aged CBA and B6 mice, expression of alpha4 and alpha7 nAChR subunits decreases with age (166). PubMed:19126755
For example, a recent study has shown that alpha7-specific ligands rescue the Abeta-induced decrease in neurite outgrowth of cultured mouse neurons (Hu et al., 2007). PubMed:19293145
This AD model displays spatial memory deficit at 13-16 months of age, while APP-alpha7KO mice did not exhibit any memory deficit, suggesting that the absence of the alpha7 subunit of the nicotinic receptor protects against the behavioural deficit caused by expression of the mutated forms of APP in this AD model PubMed:25514383
In the APP-alpha7KO line the lack of alpha7 was sufficient to preserve synaptic terminals and dendrites, rescuing levels of synaptophysin and MAP2 to reach that of aged-matched WT controls PubMed:25514383
In the APP-alpha7KO line the lack of alpha7 was sufficient to preserve synaptic terminals and dendrites, rescuing levels of synaptophysin and MAP2 to reach that of aged-matched WT controls PubMed:25514383
Signs of neuropathology were found in APP-alpha7KO illustrated by loss of MAP2 immunoreactivity in the hippocampus PubMed:25514383
The authors postulated that the absence of alpha7 could prevent Abeta intracellular accumulation ameliorating the cognitive neuropathology and its phenotypic association (Dziewczapolski et al., 2009) PubMed:25514383
In the hippocampus, it was shown that APP-alpha7KO mice had high levels of Abeta, although significantly less than APP mice, an effect which is not due to modification of the APP expression level,equivalent in the two lines PubMed:25514383
The authors postulated that the absence of alpha7 could prevent Abeta intracellular accumulation ameliorating the cognitive neuropathology and its phenotypic association (Dziewczapolski et al., 2009) PubMed:25514383
The contextual fear conditioning and the novel object recognition tasks both showed that the cognitive deficits worsen when alpha7 is absent PubMed:25514383
As a consequence of the lower Abeta concentration, the plaque load was clearly reduced in APP-alpha7KO mice PubMed:25514383
Noninjected mice spent the same amount of time exploring novel and familiar compartments during the test session (p = 0.6; Fig. 5C), confirming the presence of a constitutive recognition memory deficit in age-matched alpha7 KO mice PubMed:27522251
Because the alpha7 KO had a memory deficit independent of hAPP-SLA expression, we could not draw any conclusion on the role of alpha7 in the memory deficit observed PubMed:27522251
In the NOR task (15 months p.i.) as well, both GFP-alpha7 and APP-alpha7 displayed a cognitive impairment (Fig. 5DeE) PubMed:27522251
However, we identify a possible role of the alpha7 subunit in the normal aging process that should be further investigated PubMed:27522251
Immunofluorescence performed with VHH 31-1 on brain slices of APP-alpha7 mice also showed intracellular Abeta oligomers in the polymorphic layer (Fig. 8, arrows), whereas GFP-alpha7 mice did not show any Abeta oligomers PubMed:27522251
Notably, PHA could completely block the Ab-impaired task acquisition and reduce escape-latency to the normal level. Furthermore, the effect of PHA against the Ab-impaired task acquisition could be abolished by the pre-treatment of the a7 nAChR antagonist MLA (p<0.001). It was also noted that blockade of a7 nAChR by MLA in the Gal-treated group resulted in a significant prolongation of the escape-latency on comparing with the Gal group (p<0.001) (Fig. 2). PubMed:25881725
Effect of a7 nAChRs blockage on time spent in target quadrant in probe trials. The implications of the a7 nAChRs on PHA- or Gal-induced spatial memory enhancement were investigated by pretreatment with normal saline or MLA. A two-way ANOVA revealed significant differences of treatment [F(1,56)=4.24, p<0.05], pretreatment [F(1,56)=96.87, p<0.001] and treatment pretreatment interaction [F(1,32)=10.69, p<0.01]. Inter-group analysis showed that this effect was blocked by the selective a7 nAChR antagonist MLA (p<0.001). PubMed:25881725
Post hoc analysis revealed that, levels of the a7 nAChR protein in normal saline-treated AD mice were significantly lower than its level in the control animals (p<0.001). PubMed:25881725
α7 nAChRs are essential for the plasticity of the airway epithelium as α7 Ko mice show altered basal cell layer formation, hyperplasia, and uncontrolled growth PubMed:28901280
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If you find BEL Commons useful in your work, please consider citing: Hoyt, C. T., Domingo-Fernández, D., & Hofmann-Apitius, M. (2018). BEL Commons: an environment for exploration and analysis of networks encoded in Biological Expression Language. Database, 2018(3), 1–11.