Neuroprotective effects of HTR1A antagonist WAY-100635 on scopolamine-induced delirium in rats and underlying molecular mechanisms

BACKGROUND

Limited surveys have assessed the performance of 5-hydroxytreptamine receptor 1A and its antagonist WAY-100635 in pharmacological manipulations targeting delirium therapies. The purpose of this paper was to assess the central pharmacological activity of WAY-100635 in a rat model of scopolamine-induced delirium and its underlying mechanism.

RESULTS

A delirium rat model was established by intraperitoneal injection of scopolamine and behavioral changes evaluated through open field and elevated plus maze experiments. Concentrations of monoamines in the hippocampus and amygdalae were detected by high performance liquid chromatography. The effect of WAY-100635 on the recovery of rats from delirium was assessed by stereotactic injection of WAY-100635 and its mechanism of action determined by measuring mRNA and protein expression via real time PCR and western blotting methods. The total distance and the number of crossing and rearing in the elevated plus maze test and the time spent in the light compartment in the dark/light test of scopolamine-treated rats were significantly increased while the percentage of time spent in the open arms was decreased, showing the validity of the established delirium rat model. The measurement of the concentrations of noradrenaline, 3,4-dihydroxyphenylacetic acid, the homovanillic acid, 5-hydroxy-3-indoleacetic acid and serotonin concentrations in the cerebrospinal fluid (CSF) of scopolamine-induced delirium rats were significantly increased. The intra-hippocampus and intra-BLA injections of WAY-100635 improved the delirium-like behavior of rats by significantly reducing the expression of NLRP3 inflammasome and the release of IL1-β and IL8 into CSF.

CONCLUSIONS

Taken together, these findings indicate that WAY-100635 may exert a therapeutic effect on post-operative delirium by controlling neurotransmission as well as suppressing neuroinflammation in the central nervous system.

Postoperative Delirium in Patients Undergoing Total Joint Arthroplasty: A Systematic Review

We systematically reviewed the English-language literature to assess the incidence, risk factors and prevention strategies for postoperative delirium following total joint arthroplasty (TJA). A total of 10 studies were included in the final review, of which 3 (30%) were Level I studies, 6 were Level II (60%) studies and 1 (10%) was a Level III study. Incidence of postoperative delirium ranged from 5% to 14.3%. Pre-screening of patients was shown to reduce its incidence. Independent predictors include age, history of psychiatric illness, decreased functional status and decreased verbal memory.

Management of delirium in palliative care: a review

Delirium is a complex but common disorder in palliative care with a prevalence between 13 and 88 % but a particular frequency at the end of life (terminal delirium). By reviewing the most relevant studies (MEDLINE, EMBASE, PsycLit, PsycInfo, Cochrane Library), a correct assessment to make the diagnosis (e.g., DSM-5, delirium assessment tools), the identification of the possible etiological factors, and the application of multicomponent and integrated interventions were reported as the correct steps to effectively manage delirium in palliative care. In terms of medications, both conventional (e.g., haloperidol) and atypical antipsychotics (e.g., olanzapine, risperidone, quetiapine, aripiprazole) were shown to be equally effective in the treatment of delirium. No recommendation was possible in palliative care regarding the use of other drugs (e.g., α-2 receptors agonists, psychostimulants, cholinesterase inhibitors, melatonergic drugs). Non-pharmacological interventions (e.g., behavioral and educational) were also shown to be important in the management of delirium. More research is necessary to clarify how to more thoroughly manage delirium in palliative care.