Enriched environment ameliorates learning and memory deficits in hepatic encephalopathy mice by restoration of the structure of dendrites and dendritic spines

Cognitive impairment is one of the most common symptoms of hepatic encephalopathy (HE). However, there is a lack of easily implementable rehabilitation strategies. As an easy-to-implement strategy, numerous studies suggest that enriched environment (EE) can be beneficial for cognitive function. However, the effects of EE on learning and memory, as well as dendritic spines plasticity in HE is still unclear. Accordingly, in the present study, we evaluated the effects of EE on the behavior and dendritic spine morphology in an animal model of HE. Our results showed that HE mice have no movement disorder and anxiety, but they exhibit spatial learning and memory dysfunction. Further analysis revealed that the complexity of the dendrites and the maturity of the dendritic spines are reduced in the hippocampus of HE mice. After 4 weeks of housekeeping in EE, dendritic complexity, and dendritic spine maturity, as well as the spatial learning and memory function of HE mice were restored. In conclusion, exposure to EE can positively influence dendritic spines plasticity in the hippocampus and thereby elicit its beneficial effects on cognitive functions in HE.

Effects of enriched environment on the expression of β-amyloid and transport-related proteins LRP1 and RAGE in chronic sleep-deprived mice

Sleep plays an important role in the learning process and memory consolidation, and sleep deprivation (SD) leads to inadequate memory consolidation and plays an important role in brain development and plasticity. SD increases β-amyloid levels while impairing cognitive function. We explored the effect of enriched environment (EE) on β-amyloid and transporter protein LRP1 and receptor for advanced glycosylation end-products (RAGE) expression in chronic sleep deprived mice. We randomly divided mice into four groups (n = 10), the standard environment group (Ctrl group), the sleep deprivation group (SD group), the enriched environment intervention group (EE group), and the sleep deprivation plus environmental enrichment intervention group (SD + EE group). A modified multi-platform SD model was used to sleep deprive the mice for 19 h per day. Five hours of EE intervention was performed daily in the EE group and the SD + EE group, respectively. The behavioral measurements of mice were performed by Y-maze method and new object recognition; the expression levels of Aβ1-42, LRP1, and RAGE in prefrontal cortex and hippocampus of mice were measured by immunofluorescence; the expression levels of LRP1 and RAGE in prefrontal cortex and hippocampus were detected by Western blot. The results showed that EE could effectively ameliorate the effects of SD on cognitive impairment, reduce SD induced Aβ deposition, and decrease the expression of RAGE, while increase the expression of LRP1.

Environmental enrichment for stroke and other non-progressive brain injury

BACKGROUND

Rehabilitation is effective for recovery after stroke and other non-progressive brain injuries but it is unclear if the rehabilitation environment itself, outside of limited therapy hours, is maximally conducive to recovery. Environmental enrichment is a relatively new concept within rehabilitation for humans. In this review, this is defined as an intervention designed to facilitate physical (motor and sensory), cognitive and social activity by the provision of equipment and organisation of a structured, stimulating environment. The environment should be designed to encourage (but not force) activities without additional specialised rehabilitation input.

OBJECTIVES

To assess the effects of environmental enrichment on well-being, functional recovery, activity levels and quality of life in people who have stroke or non-progressive brain injury.

SEARCH METHODS

We conducted the search on 26 October 2020. We searched the Cochrane Central Register of Controlled Trials (CENTRAL) in the Cochrane Library; MEDLINE (from 1950); Embase (from 1980); the Cumulative Index to Nursing and Allied Health Literature (CINAHL; from 1982); the Allied and Complementary Medicine Database (AMED; from 1985); PsycINFO (from 1806); the Physiotherapy Evidence Database (PEDro; from 1999); and 10 additional bibliographic databases and ongoing trial registers.

SELECTION CRITERIA

We planned to include randomised controlled trials (RCTs) that compared environmental enrichment with standard services.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed eligible studies, extracted data, and assessed study quality. Any disagreements were resolved through discussion with a third review author. We determined the risk of bias for the included study and performed a 'best evidence' synthesis using the GRADE approach.

MAIN RESULTS

We identified one RCT, involving 53 participants with stroke, comparing environmental enrichment (which included physical, cognitive and social activities such as reading material, board and card games, gaming technology, music, artwork, and computer with Internet) with standard services in an inpatient rehabilitation setting. We excluded five studies, found two studies awaiting classification and one ongoing study which described environmental enrichment in their interventions. Of the excluded studies, three were non-RCTs and two described co-interventions with a significant component of rehabilitation. Based on the single small included RCT at high risk of bias, data are insufficient to provide any reliable indication of benefit or risk to guide clinical practice in terms of the provision of environmental enrichment.

AUTHORS' CONCLUSIONS

The gap in current research should not, however, be interpreted as proof that environmental enrichment is ineffective. Further research is needed with robust study designs, such as cluster RCTs, and consistent outcome measurement evaluating the effectiveness of environmental enrichment in different settings (inpatient versus outpatient), the relative effectiveness of various components of environmental enrichment, cost-effectiveness, and safety of the intervention in people following stroke or other non-progressive brain injuries. It should be noted, however, that it is challenging to randomise or double-blind trials of environmental enrichment given the nature of the intervention.

Effectiveness and mechanisms of enriched environment in post-stroke cognitive impairment

Post-stroke cognitive impairment (PSCI) is one of the most common complications of stroke, it is also an important reason for the poor prognosis in stroke patients with motor and speech dysfunction. Enriched Environment (EE), a novel and easy-to-implement rehabilitation treatment strategy, is thought to be a potential intervention for PSCI recently. In this paper, we review the therapeutic effects and related mechanisms of EE in PSCI from the level of animal research and clinical application. Besides, we further discuss the application prospects and limitations of EE in PSCI patients.