Brain targeting efficacy of novel drug delivery system in the treatment of Alzheimer's disease.

OBJECTIVE: Alzheimer's disease (AD), a common degenerative disease of the central nervous system in the elderly, has become the third largest health killer after cardiovascular and cerebrovascular diseases and tumors. Based on the fact that Alzheimer's disease is a disease with multiple etiologies and complex pathology, a single target is bound to have a limited curative effect, and the synergy of multiple links and multiple targets is expected to achieve a better curative effect. The aim of this study is to investigate the brain targeting of a drug modified by chitosan, based on the new nanodrug delivery system for treating Alzheimer's disease developed by the research group. MATERIALS AND METHODS: Chitosan with good biocompatibility, biosorption, and degradation products that can protect and promote the regeneration of nerve cells was selected to combine with galantamine, a natural representative cholinesterase inhibitor, to develop a new nano drug delivery system for nasal delivery of anti-Alzheimer's disease with a multi-target synergistic effect. Synchronous analysis was conducted on the blood and brain tissue drug concentrations after intravenous and nasal administration of the original drug solution and system solution. The brain targeting index (DTI) is used to evaluate the brain targeting effect of the nano-drug delivery system after intranasal administration. RESULTS: The blood concentration of galantamine original drug solution and galantamine system solution after intravenous injection and nasal show that in the two administration methods of intravenous injection and nasal administration, under the same administration method, the time point of the system reaching the highest blood drug concentration is much higher than that of the original drug. The content of galantamine in plasma samples and tissue samples indicate that after intravenous administration and intranasal administration of the galantamine system, at the same time point, the drug concentration in brain tissue was far greater than that of the original drug of galantamine, and the duration was also longer. The concentration of drugs in brain tissue decreased gradually in the order of olfactory bulb, olfactory tract, brain, and cerebellum. In the brain tissues of the olfactory bulb, olfactory tract, cerebrum, and cerebellum, the drug concentration of the galantamine system after intravenous injection is lower than that after nasal administration. CONCLUSIONS: This study concludes that compared with the original drug solution, the nano drug delivery system has significant brain targeting for nasal administration, and intravenous injection also has brain targeting. In the olfactory bulb, olfactory tract, brain, and cerebellum, the brain targeting index at the olfactory bulb is the highest, and the targeting is the best.

Effect of curcumin-donepezil combination on spatial memory, astrocyte activation, and cholinesterase expressions in brain of scopolamine-treated rats.

BACKGROUND: The study investigated the effect of co-administration of curcumin and donepezil on several markers of cognitive function (such as spatial memory, astrocyte activation, cholinesterase expressions) in the brain cortex and hippocampus of scopolamine-treated rats. METHOD AND RESULTS: For seven consecutive days, a pre-treatment of curcumin (50 mg/kg) and/or donepezil (2.5 mg/kg) was administered. On the seventh day, scopolamine (1 mg/kg) was administered to elicit cognitive impairment, 30 min before memory test was conducted. This was followed by evaluating changes in spatial memory, cholinesterase, and adenosine deaminase (ADA) activities, as well as nitric oxide (NO) level were determined. Additionally, RT-qPCR for glial fibrillary acidic protein (GFAP) and cholinesterase gene expressions was performed in the brain cortex and hippocampus. Also, GFAP immunohistochemistry  of the brain tissues for neuronal injury were performed in the brain cortex and hippocampus. In comparison to the control group, rats given scopolamine had impaired memory, higher levels of acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and ADA activities, as well as elevated markers of oxidative stress. In addition to enhanced GFAP immunoreactivity, there was also overexpression of the GFAP and BChE genes in the brain tissues. The combination of curcumin and donepezil was, however, observed to better ameliorate these impairments in comparison to the donepezil-administered rat group. CONCLUSION: Hence, this evidence provides more mechanisms to support the hypothesis that the concurrent administration of curcumin and donepezil mitigates markers of cognitive dysfunction in scopolamine-treated rat model.

The effect of chlorpyrifos oral exposure on the histomorphometric and kidney function in Wistar rat.

BACKGROUND: Chlorpyrifos belongs to a broad-spectrum organophosphate insecticide that has high toxicity, is metabolized in the liver by the oxidation reaction, and can inhibit acetylcholinesterase activity. Acetylcholinesterase inhibition generates the reactive oxygen species and induces oxidative stress, which ultimately results in cellular damage like in the kidney. Examining blood urea nitrogen (BUN) levels, creatinine, and kidney histopathology is an appropriate indicator to assess the toxicity of chlorpyrifos to the degree of damage to cells and kidney tissue. MATERIALS AND METHODS: This research used to determine the effect of duration of exposure to chlorpyrifos and dose-response relationships is important for early detection of the effects of chlorpyrifos toxicity on health. The research study was a true experimental (completely randomized design) consisting of 30 subjects divided into 5 groups. Controlled Group (K1) given 1 mg/kg BW Tween 20 and NaCl 0, 9% until the 56th day. The chlorpyrifos exposed group (P1, P2, P3, and P4) was given chlorpyrifos 5 mg/kg BW for 7, 14, 28, and 56 days. After the treatment, BUN and creatinine levels were measured, and microscopic changes in the kidney were analyzed. The results of BUN, creatinine, and kidney histopathologic were analyzed using the analysis of variance statistical test. RESULTS: The data result showed that compared to the control group, there were significant increases of BUN and creatinine (P = 0.013 and P = 0.003). Histopathological examinations of kidney glomerulus diameter were also smaller compared to the control group (P = 0.00). All the data measurement indicates significant differences compared to the control group. CONCLUSIONS: We concluded that sub-chronic oral exposure to chlorpyrifos at low doses can damage the kidneys and cause kidney failure.

Implantable trilayer microneedle transdermal delivery system to enhance bioavailability and brain delivery of rivastigmine for Alzheimer treatment: A proof-of-concept study.

Alzheimer's disease (ALZ) is a neurological disorder characterized by cognitive decline. Rivastigmine (RV), an acetylcholinesterase inhibitor, is commonly used to treat ALZ. Unfortunately, RV is availablein capsule form, which is associated with low drug bioavailability, and in patch form, which can lead to skin irritation upon repeated use. This study successfully fabricated a trilayer dissolving microneedle (TDMN) containing RV with adequate mechanical strength by using the molding method. In vitro release and ex vivo permeation showed that the release and permeation of RV were significantly sustained compared to control without PCL. The release and permeation percentages were 91.34 ± 11.39 % and 13.76 ± 1.49 µg/cm2, respectively. In addition, the concentration of RV in plasma and brain after 168 h was measured to be 0.44 ± 0.09 µg/mL and 1.23 ± 0.26 µg/g, respectively, which reached the minimum concentration to inhibit AcHE and BuChe. Pharmacokinetic testing revealed higher AUC values after administration of TDMN, indicating better bioavailability and RV concentrations in the brain were twice as high as those achieved with oral administration. This study suggests TDMN may enhance the bioavailability and brain delivery of RV.

Oxime-functionalized anti-insecticide fabric reduces insecticide exposure through dermal and nasal routes, and prevents insecticide-induced neuromuscular-dysfunction and mortality.

Farmers from South Asian countries spray insecticides without protective gear, which leads to insecticide exposure through dermal and nasal routes. Acetylcholinesterase plays a crucial role in controlling neuromuscular function. Organophosphate and carbamate insecticides inhibit acetylcholinesterase, which leads to severe neuronal/cognitive dysfunction, breathing disorders, loss of endurance, and death. To address this issue, an Oxime-fabric is developed by covalently attaching silyl-pralidoxime to the cellulose of the fabric. The Oxime-fabric, when stitched as a bodysuit and facemask, efficiently deactivates insecticides (organophosphates and carbamates) upon contact, preventing exposure. The Oxime-fabric prevents insecticide-induced neuronal damage, neuro-muscular dysfunction, and loss of endurance. Furthermore, we observe a 100% survival rate in rats when repeatedly exposed to organophosphate-insecticide through the Oxime-fabric, while no survival is seen when organophosphate-insecticide applied directly or through normal fabric. The Oxime-fabric is washable and reusable for at least 50 cycles, providing an affordable solution to prevent insecticide-induced toxicity and lethality among farmers.

Pyridostigmine to Reduce the duration of postoperative Ileus after Colorectal surgery (PyRICo-RCT): randomized clinical trial.

BACKGROUND: Postoperative ileus, driven by the cholinergic anti-inflammatory pathway, is the most common complication in patients undergoing colorectal surgery. By inhibiting acetylcholinesterase, pyridostigmine can potentially modulate the cholinergic anti-inflammatory pathway and accelerate gastrointestinal recovery. This study aimed to assess the efficacy of pyridostigmine in improving gastrointestinal recovery after colorectal surgery. METHODS: This double-blinded RCT enrolled adult patients undergoing elective colorectal surgery at two hospitals in South Australia. Patients were randomized to 60 mg oral pyridostigmine or placebo twice daily starting 6 h after surgery until the first passage of stool. The primary outcome was GI-2, a validated composite measure of time to first stool and tolerance of oral diet. Secondary outcomes included incidence of postoperative ileus (defined as GI-2 greater than 4 days), duration of hospital stay, and 30-day complications, evaluated by intention-to-treat univariate analysis. RESULTS: Of 130 patients recruited (mean(s.d.) age 58.4(16.4) years; 73 men, 56%), 65 were allocated to each arm. The median GI-2 was 1 day shorter with pyridostigmine compared with placebo (2 (i.q.r. 1-3) versus 3 (2-4) days; P = 0.015). However, there were no significant differences in postoperative ileus (17.2 versus 21.5%; P = 0.532) or duration of hospital stay (median 5 (i.q.r. 4-8.75) versus 5 (4-7.5) days; P = 0.921). Similarly, there were no significant differences in overall complications, anastomotic leak, cardiac complications, or patient-reported side effects. CONCLUSION: Pyridostigmine resulted in a quicker return of GI-2 and was well tolerated. Larger multicentre studies are required to determine the optimal dosing and evaluate the impact of pyridostigmine in different surgical settings. Registration number: ACTRN12621000530820 (https://anzctr.org.au).

The donepezil transdermal system for the treatment of patients with mild, moderate, or severe Alzheimer's disease: a critical review.

INTRODUCTION: Cholinesterase inhibitors, along with memantine, are the mainstay of symptomatic treatment for AD (Alzheimer's disease); however, these medications are typically administered orally, which can be difficult for people with AD and their caregivers. AREAS COVERED: In this drug profile and narrative review, the authors trace the development of the new FDA-approved transdermal donepezil. The authors discuss the studies showing its bioequivalence with the oral formulation, including two double-blinded placebo controlled non-inferiority trials. The authors also compare the patch to the only other transdermal cholinesterase inhibitor on the market, rivastigmine, and highlight the potential advantages and disadvantages between these two treatments. EXPERT OPINION: While the patch is bio-equivalent, it is rather large and may not be affordable for some patients. In addition, there is no high dose (e.g. 23 mg) equivalent. Nevertheless, transdermal donepezil will be useful for people with AD and their caregivers, given its effectiveness and potential convenience.

Effect of coadministration of 10 mg/kg calcium chloride and neostigmine on extubation time: A randomized controlled trial.

INTRODUCTION AND OBJECTIVES: Some studies investigating the effect of calcium on neostigmine-induced recovery of neuromuscular blockade have shown that this combination promotes neuromuscular recovery, but does not significantly affect the incidence of postoperative residual curarization and time to extubation. This study aimed to evaluate the effects of 10 mg/kg calcium chloride co-administered with neostigmine on early recovery and time to extubation. PATIENTS AND METHODS: This prospective, randomized, double-blinded, placebo-controlled study included 88 ASA I-II patients aged between 18 and 65 years who were scheduled for elective surgery lasting at least 1 h under general anaesthesia in which 10 mg/kg of calcium chloride or the same volume of normal saline was co-administered with 5 µg/kg of neostigmine at the end of surgery. Time to extubation (time from neostigmine administration to extubation), time from neostigmine administration to TOF ratio (TOFr) 0.9 (neuromuscular recovery), and the incidence of residual neuromuscular blockade (RNMB) and other adverse effects were recorded. RESULTS: Median (Q1, Q3) extubation time was significantly shorter in the calcium group vs. the placebo group (6.5 min [5.52-7.43] vs. 9.78 min [8.35-11]), P < .001. Median neuromuscular recovery time in the calcium group was 5 min vs. 7.1 min in the placebo group, P < .001. Patients in the calcium group had significantly higher TOFr and lower incidence of RNMB at 5 and 10 min vs. the placebo group, and no significant side effects. CONCLUSION: Calcium chloride at a dose of 10 mg/kg co-administered with neostigmine promotes early neuromuscular recovery and reduces time to extubation by about 32%.

The value of cholinesterase inhibitors for improving neuropsychiatric and functional assessment scores in patients with Alzheimer disease: a systematic review and meta-analysis of on placebo-controlled RCTs.

INTRODUCTION: At present, increasing reports from different aspects indicated that cholinesterase inhibitors (ChEIs) may be effective on improving neuropsychiatric and functional assessment scores in patients with Alzheimer disease (AD). However, no studies comprehensively and detailedly evaluated the effect of ChEIs on AD. The present analysis was designed to comprehensively evaluate the efficacy and safety of ChEIs for AD. METHODS: Two independent researchers systematically reviewed 1096 searching records in PubMed, Embase, Cochrane Library, and Web of Science from inception to 10 May 2023, and finally identified 12 randomized, double-blind, placebo-controlled trials with 6908 participants according to predetermined inclusion and exclusion criteria. The effects were assessed with standardized mean difference (SMD) or odds ratio (OR). The primary outcomes were the mean change and least squares (LS) mean change from baseline to endpoint of neuropsychiatric and functional assessment scores. The secondary outcome was adverse events of ChEIs when compared to placebo for patients with AD. All statistical analyses were performed using the standard statistical procedures provided in Review Manager 5.2 and and Stata 12.0. RESULTS: Pooled analysis indicated that ChEIs significantly improved the assessment scores of the AD Assessment Scale (ADAS) (SMD -1.57; 95% CI: -2.64 to -0.51), Clinician's Interview-Based Impression of Change-Plus caregiver input (CIBIC-Plus) (SMD -0.28; 95% CI: -0.41 to -0.15), the Neuropsychiatric Inventory (NPI) (both SMD -1.67; 95% CI: -2.88 to -0.47 for 10-tiem total score and SMD -1.83; 95% CI: -3.25 to -0.42 for 12-tiem total score), and the AD Cooperative Study-Activities of Daily Living (ADCS-ADL) total score (SMD 2.44; 95% CI: 1.29-3.59), evaluated with mean change from baseline to endpoint. In addition, when evaluated with the LS mean change from baseline to endpoint, ChEIs significantly improved Mini-Mental State Examination (MMSE) total score, the Clinician Interview-Based Impression of Severity, CIBIC-Plus, ADCS-ADL total score, NPI, ADAS. Regarding to adverse events (AEs) of patients with AD, it indicated that compared to placebo, ChEIs did not increase the frequency of severe and serious AEs (fatal or nonfatal) as well as the incidence of death. CONCLUSIONS: Our analysis indicated that ChEIs treatment generally improved neuropsychiatric and functional assessment scores in patients with AD though opposite result was observed in Wechsler Memory Scale. ChEIs had an acceptable safety profile in patients with AD without increasing of any crucial adverse or outcomes.

Nose-to-Brain Targeted Delivery of Donepezil Hydrochloride via Novel Hyaluronic Acid-Doped Nanotransfersomes for Alzheimer's Disease Mitigation.

Alzheimer's disease is the most serious neurodegenerative disorder characterized by cognitive and memorial defects alongside deterioration in behavioral, thinking and social skills. Donepezil hydrochloride (DPZ) is one of the current two FDA-approved cholinesterase inhibitors used for the management of Alzheimer's disease. The current study aimed to formulate hyaluronic acid-coated transfersomes containing DPZ (DPZ-HA-TFS) for brain delivery through the intranasal pathway to surpass its oral-correlated GIT side effects. DPZ-HA-TFS were produced using a thin film hydration method and optimized with a 24 factorial design. The influence of formulation parameters on vesicle diameter, entrapment, cumulative release after 8 h, and ex vivo nasal diffusion after 24 h was studied. The optimal formulation was then evaluated for morphology, stability, histopathology and in vivo biodistribution studies. The optimized DPZ-HA-TFS formulation elicited an acceptable vesicle size (227.5 nm) with 75.83% entrapment efficiency, 37.94% cumulative release after 8 h, 547.49 µg/cm2 permeated through nasal mucosa after 24 h and adequate stability. Histopathological analysis revealed that the formulated DPZ-HA-TFS was nontoxic and tolerable for intranasal delivery. Intranasally administered DPZ-HA-TFS manifested significantly superior values for drug targeting index (5.08), drug targeting efficiency (508.25%) and direct nose-to-brain transport percentage (80.32%). DPZ-HA-TFS might be deemed as a promising intranasal nano-cargo for DPZ cerebral delivery to tackle Alzheimer's disease safely, steadily and in a non-invasive long-term pattern.

Balanced modulation of neuromuscular synaptic transmission via M1 and M2 muscarinic receptors during inhibition of cholinesterases.

Organophosphorus (OP) compounds that inhibit acetylcholinesterase are a common cause of poisoning worldwide, resulting in several hundred thousand deaths each year. The pathways activated during OP compound poisoning via overstimulation of muscarinic acetylcholine receptors (mAChRs) play a decisive role in toxidrome. The antidotal therapy includes atropine, which is a nonspecific blocker of all mAChR subtypes. Atropine is efficient for mitigating depression in respiratory control centers but does not benefit patients with OP-induced skeletal muscle weakness. By using an ex vivo model of OP-induced muscle weakness, we studied the effects of the M1/M4 mAChR antagonist pirenzepine and the M2/M4 mAChR antagonist methoctramine on the force of mouse diaphragm muscle contraction. It was shown that weakness caused by the application of paraoxon can be significantly prevented by methoctramine (1 µM). However, neither pirenzepine (0.1 µM) nor atropine (1 µM) was able to prevent muscle weakness. Moreover, the application of pirenzepine significantly reduced the positive effect of methoctramine. Thus, balanced modulation of neuromuscular synaptic transmission via M1 and M2 mAChRs contributes to paraoxon-induced muscle weakness. It was shown that methoctramine (10 µmol/kg, i.p.) and atropine (50 µmol/kg, i.p.) were equieffective toward increasing the survival of mice poisoned with a 2xLD50 dose of paraoxon.

Coincidental Onset of Ocular Myasthenia Gravis Following ChAdOx1 n-CoV-19 Vaccine against Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2).

BACKGROUND: The Oxford-AstraZeneca vaccine ChAdOx1 (AZD1222, Vaxzevria) is playing a crucial role in counteracting the coronavirus disease-2019 (COVID-19) pandemic [1]. Since March 2021, reports of unexpected thrombotic events associated with thrombocytopenia and vaccination have been published [2]. To the best of our knowledge there is only one report about vaccination-associated myasthenia gravis (MG) occurring after a second dose of BNT162b2 (Pfizer-BioNTech).

Effects of Increased Central Cholinergic Activity on the Metabolic Challenge Induced by Submaximal Exercise in Rats: Adrenomedullary Secretion Influences.

AIM: The aim of this study was to assess the influence of adrenomedullary secretion on the plasma glucose, lactate, and free fatty acids (FFAs) during running exercise in rats submitted to intracerebroventricular (i.c.v.) injection of physostigmine (PHY). PHY i.c.v. was used to activate the central cholinergic system. METHODS: Wistar rats were divided into sham-saline (sham-SAL), sham-PHY, adrenal medullectomy-SAL, and ADM-PHY groups. The plasma concentrations of glucose, lactate, and FFAs were determined immediately before and after i.c.v. injection of 20 µL of SAL or PHY at rest and during running exercise on a treadmill. RESULTS: The i.c.v. injection of PHY at rest increased plasma glucose in the sham group, but not in the ADM group. An increase in plasma glucose, lactate, and FFAs mobilization from adipose tissue was observed during physical exercise in the sham-SAL group; however, the increase in plasma glucose was greater with i.c.v. PHY. Moreover, the hyperglycemia induced by exercise and PHY in the ADM group were blunted by ADM, whereas FFA mobilization was unaffected. CONCLUSION: These results indicate that there is a dual metabolic control by which activation of the central cholinergic pathway increases plasma glucose but not FFA during rest and exercise, and that this hyperglycemic response is dependent on adrenomedullary secretion.

Induction of distinct neuroinflammatory markers and gut dysbiosis by differential pyridostigmine bromide dosing in a chronic mouse model of GWI showing persistent exercise fatigue and cognitive impairment.

AIMS: To characterize neuroinflammatory and gut dysbiosis signatures that accompany exaggerated exercise fatigue and cognitive/mood deficits in a mouse model of Gulf War Illness (GWI). METHODS: Adult male C57Bl/6N mice were exposed for 28 d (5 d/wk) to pyridostigmine bromide (P.O.) at 6.5 mg/kg/d, b.i.d. (GW1) or 8.7 mg/kg/d, q.d. (GW2); topical permethrin (1.3 mg/kg), topical N,N-diethyl-meta-toluamide (33%) and restraint stress (5 min). Animals were phenotypically evaluated as described in an accompanying article [124] and sacrificed at 6.6 months post-treatment (PT) to allow measurement of brain neuroinflammation/neuropathic pain gene expression, hippocampal glial fibrillary acidic protein, brain Interleukin-6, gut dysbiosis and serum endotoxin. KEY FINDINGS: Compared to GW1, GW2 showed a more intense neuroinflammatory transcriptional signature relative to sham stress controls. Interleukin-6 was elevated in GW2 and astrogliosis in hippocampal CA1 was seen in both GW groups. Beta-diversity PCoA using weighted Unifrac revealed that gut microbial communities changed after exposure to GW2 at PT188. Both GW1 and GW2 displayed systemic endotoxemia, suggesting a gut-brain mechanism underlies the neuropathological signatures. Using germ-free mice, probiotic supplementation with Lactobacillus reuteri produced less gut permeability than microbiota transplantation using GW2 feces. SIGNIFICANCE: Our findings demonstrate that GW agents dose-dependently induce differential neuropathology and gut dysbiosis associated with cognitive, exercise fatigue and mood GWI phenotypes. Establishment of a comprehensive animal model that recapitulates multiple GWI symptom domains and neuroinflammation has significant implications for uncovering pathophysiology, improving diagnosis and treatment for GWI.

Anticholinesterase activity of ß-carboline-1, 3, 5-triazine hybrids

Abstract The ß-carboline-1,3,5-triazine hydrochlorides 8-13 were evaluated in vitro against acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE). The analysed compounds were selective to BuChE, with IC50 values in the range from 1.0-18.8 µM being obtained. The N-{2-[(4,6-dihydrazinyl-1,3,5-triazin-2-yl)amino]ethyl}-1-phenyl-ß-carboline-3-carboxamide (12) was the most potent compound and kinetic studies indicate that it acts as a competitive inhibitor of BuChE. Molecular docking studies show that 12 strongly interacts with the residues of His438 (residue of the catalytic triad) and Trp82 (residue of catalytic anionic site), confirming that this compound competes with the same binding site of the butyrylthiocholine

Tetradenia riparia leaves, flower buds, and stem essential oils to control of Aedes aegypti larvae

Abstract Tetradenia riparia (Hochst.) Codd (Lamiaceae) is a species native to the African continent and used as an insect repellent. The objective of the study was to evaluate the larvicidal potential of essential oils (EOs) from the leaves, flower buds, and stem of T. riparia, collected in winter against Aedes aegypti larvae. The EOs were extracted by hydrodistillation (3 h) and identified by GC/MS. The EOs were tested against larvae of A. aegypti at concentrations ranging from 12500 to 1.5 µg/mL for 24 h. The insecticide activity was evaluated by probit analysis, and the anticholinesterase activity was determined by bioautographic method. The results of the class projection indicated sesquiterpenes as the majority class, corresponding to 60.66% (leaves), 64.70% (flower buds) and 83.99% (stem), and the bioassays on A. aegypti larvae indicated LC50 of 1590, 675 and 665 µg/mL, respectively. The anticholinesterase activity indicated that the EO of the leaves inhibited the enzyme at a concentration of 780 µg/mL, and those from the flower buds and stem inhibited up to 1560 µg/mL. The results indicated weak activity of essential oils against A. aegypti larvae.

Effect of Intrahippocampal Administration of α7 Subtype Nicotinic Receptor Agonist PNU-282987 and Its Solvent Dimethyl Sulfoxide on the Efficiency of Hypoxic Preconditioning in Rats.

We have previously suggested a key role of the hippocampus in the preconditioning action of moderate hypobaric hypoxia (HBH). The preconditioning efficiency of HBH is associated with acoustic startle prepulse inhibition (PPI). In rats with PPI > 40%, HBH activates the cholinergic projections of hippocampus, and PNU-282987, a selective agonist of α7 nicotinic receptors (α7nAChRs), reduces the HBH efficiency and potentiating effect on HBH of its solvent dimethyl sulfoxide (DMSO, anticholinesterase agent) when administered intraperitoneally. In order to validate the hippocampus as a key structure in the mechanism of hypoxic preconditioning and research a significance of α7nAChR activation in the hypoxic preconditioning, we performed an in vivo pharmacological study of intrahippocampal injections of PNU-282987 into the CA1 area on HBH efficiency in rats with PPI ≥ 40%. We found that PNU-282987 (30 µM) reduced HBH efficiency as with intraperitoneal administration, while DMSO (0.05%) still potentiated this effect. Thus, direct evidence of the key role of the hippocampus in the preconditioning effect of HBH and some details of this mechanism were obtained in rats with PPI ≥ 40%. The activation of α7nAChRs is not involved in the cholinergic signaling initiated by HBH or DMSO via any route of administration. Possible ways of the potentiating action of DMSO on HBH efficiency and its dependence on α7nAChRs are discussed.

Donepezil Regulates LPS and Aß-Stimulated Neuroinflammation through MAPK/NLRP3 Inflammasome/STAT3 Signaling.

The acetylcholinesterase inhibitors donepezil and rivastigmine have been used as therapeutic drugs for Alzheimer's disease (AD), but their effects on LPS- and Aß-induced neuroinflammatory responses and the underlying molecular pathways have not been studied in detail in vitro and in vivo. In the present study, we found that 10 or 50 µM donepezil significantly decreased the LPS-induced increases in the mRNA levels of a number of proinflammatory cytokines in BV2 microglial cells, whereas 50 µM rivastigmine significantly diminished only LPS-stimulated IL-6 mRNA levels. In subsequent experiments in primary astrocytes, donepezil suppressed only LPS-stimulated iNOS mRNA levels. To identify the molecular mechanisms by which donepezil regulates LPS-induced neuroinflammation, we examined whether donepezil alters LPS-stimulated proinflammatory responses by modulating LPS-induced downstream signaling and the NLRP3 inflammasome. Importantly, we found that donepezil suppressed LPS-induced AKT/MAPK signaling, the NLRP3 inflammasome, and transcription factor NF-kB/STAT3 phosphorylation to reduce neuroinflammatory responses. In LPS-treated wild-type mice, a model of neuroinflammatory disease, donepezil significantly attenuated LPS-induced microglial activation, microglial density/morphology, and proinflammatory cytokine COX-2 and IL-6 levels. In a mouse model of AD (5xFAD mice), donepezil significantly reduced Aß-induced microglial and astrocytic activation, density, and morphology. Taken together, our findings indicate that donepezil significantly downregulates LPS- and Aß-evoked neuroinflammatory responses in vitro and in vivo and may be a therapeutic agent for neuroinflammation-associated diseases such as AD.

Use of antipsychotic drugs and cholinesterase inhibitors and risk of falls and fractures: self-controlled case series.

OBJECTIVE: To evaluate the association between the use of antipsychotic drugs and cholinesterase inhibitors and the risk of falls and fractures in elderly patients with major neurocognitive disorders. DESIGN: Self-controlled case series. SETTING: Taiwan's National Health Insurance Database. PARTICIPANTS: 15 278 adults, aged ≥65, with newly prescribed antipsychotic drugs and cholinesterase inhibitors, who had an incident fall or fracture between 2006 and 2017. Prescription records of cholinesterase inhibitors confirmed the diagnosis of major neurocognitive disorders; all use of cholinesterase inhibitors was reviewed by experts. MAIN OUTCOME MEASURES: Conditional Poisson regression was used to derive incidence rate ratios and 95% confidence intervals for evaluating the risk of falls and fractures for different treatment periods: use of cholinesterase inhibitors alone, antipsychotic drugs alone, and a combination of cholinesterase inhibitors and antipsychotic drugs, compared with the non-treatment period in the same individual. A 14 day pretreatment period was defined before starting the study drugs because of concerns about confounding by indication. RESULTS: The incidence of falls and fractures per 100 person years was 8.30 (95% confidence interval 8.14 to 8.46) for the non-treatment period, 52.35 (48.46 to 56.47) for the pretreatment period, and 10.55 (9.98 to 11.14), 10.34 (9.80 to 10.89), and 9.41 (8.98 to 9.86) for use of a combination of cholinesterase inhibitors and antipsychotic drugs, antipsychotic drugs alone, and cholinesterase inhibitors alone, respectively. Compared with the non-treatment period, the highest risk of falls and fractures was during the pretreatment period (adjusted incidence rate ratio 6.17, 95% confidence interval 5.69 to 6.69), followed by treatment with the combination of cholinesterase inhibitors and antipsychotic drugs (1.35, 1.26 to 1.45), antipsychotic drugs alone (1.33, 1.24 to 1.43), and cholinesterase inhibitors alone (1.17, 1.10 to 1.24). CONCLUSIONS: The incidence of falls and fractures was high in the pretreatment period, suggesting that factors other than the study drugs, such as underlying diseases, should be taken into consideration when evaluating the association between the risk of falls and fractures and use of cholinesterase inhibitors and antipsychotic drugs. The treatment periods were also associated with a higher risk of falls and fractures compared with the non-treatment period, although the magnitude was much lower than during the pretreatment period. Strategies for prevention and close monitoring of the risk of falls are still necessary until patients regain a more stable physical and mental state.