Alzheimer’s disease (AD) is the most common form of dementia over the age of 65. It is estimated that 115.4 million people will be affected by AD by 2050. Acetylcholinesterase inhibitors (AChEI) are the only available and approved treatment for AD. The aim of the present study was to analyse the evidence on the efficacy of the AChEI in the treatment of cognitive symptoms of Alzheimer’s disease. For that purpose, a review of review of the systematic reviews (SRs) on this topic was carried out by Web of Science, PubMed, and The Cochrane Library, among others, were searched until 24 September 2021. Thirteen of the 1773 articles evaluated the efficacy of AChEI on cognitive function and/or general condition and/or behavioural disturbances of patients with mild to moderate AD. Methodological quality and risk of bias were rated using the ROBIS scale. The quality of the identified studies was high for nine of them, unclear for two, and finally only in two of the 13 studies did we detect low quality. Overall, AChEI showed very low efficacy in improving cognition in patients with mild to moderate AD. Better results were obtained in improving global state, with donepezil being the most effective treatment. No improvements in behavioural disturbances were found. Few high-quality reviews provide clear evidence of the effects of AChEI on cognition, global change, behaviour, and mortality. The data suggest that AChEI stabilize or slow cognitive deterioration, improving global status. In addition, data indicate that the use of AChEI decreases mortality in patients with mild to moderate AD. However, there is no evidence that they improve patient behaviour. Donepezil is the best therapeutic alternative at a dose of 10 mg/day.

Background: Targeting dorsal raphe (DR) 5-HT1A receptors, which are coupled to G-protein inwardly rectifying potassium (GIRK) channels, has revealed their contribution not only to behavioral and functional aspects of depression, but also to the clinical response to its treatment. Although GIRK channels containing GIRK2 subunits play an important role controlling excitability of several brain areas, their impact on the DR activity is still unknown. Thus, the goal of the present study was to investigate in vivo the involvement of GIRK2 subunit-containing GIRK channels in depression-related behaviors and physiology of serotonergic (5-HT) neurotransmission. Methods: Behavioral, functional, including in vivo extracellular recordings of DR neurons, and neurogenesis studies were carried out in wild-type (WT) and GIRK2 mutant mice. Results: Deletion of the GIRK2 subunit promoted a depression-resistant phenotype and determined the behavioral response to the antidepressant citalopram without altering hippocampal neurogenesis. In the DR neurons of GIRK2 knockout mice (GIRK2-/-), and also using GIRK channel blocker tertiapin-Q, the basal firing rate was higher than that obtained in WT animals, although no differences were observed in other firing parameters. 5-HT1A receptors were desensitized in GIRK2-/- mice, as demonstrated by a lower sensitivity of DR neurons to the inhibitory effect of the 5-HT1A receptor agonist, 8-OH-DPAT and the antidepressant citalopram. Conclusions: Our results indicate that GIRK channels formed by GIRK2 subunits determine depression-related behaviors as well as basal and 5-HT1A receptor-mediated DR neuronal activity, becoming alternative therapeutical targets for psychiatric diseases underlying dysfunctional 5-HT transmission.

Acetylcholinesterase (AChE) is responsible for hydrolyzing the acetylcholine neurotransmitter, bringing an end point to cholinergic neurotransmission. Thus, AChE is the primary target of a wide spectrum of compounds used as pesticides, nerve agents or therapeutic drugs for neurodegenerative diseases such as Alzheimer’s disease (AD). This enzyme is heterogeneously distributed in the brain showing different activity depending on the nervous region. Therefore, the aim of this work is to report a novel technology that enables the simultaneous determination of tissue specific AChE activity, as well as the analysis and screening of specific inhibitors, by using cell membrane microarrays. These microarrays were composed of cell membranes, isolated from 41 tissues, organs and brain areas, that were immobilized over a slide, maintaining the functionality of membrane proteins. To validate this platform, demonstrating its usefulness in drug discovery as a high throughput screening tool, a colorimetric protocol to detect the membrane-bound AChE activity was optimized. Thus, rat cortical and striatal AChE activities were estimated in presence of increased concentrations of AChE inhibitors, and the donepezil effect was assessed simultaneously in 41 tissues and organs, demonstrating the major potential of this microarray’s technology.