Complicated Role of Exercise in Modulating Memory: A Discussion of the Mechanisms Involved

Comparing the effect of fluoxetine, escitalopram, and sertraline, on the level of BDNF and depression in preclinical and clinical studies: a systematic review

Brain-derived neurotrophic factor (BDNF) dysfunction is one of the most important mechanisms underlying depression. It seems that selective serotonin reuptake inhibitors (SSRIs) improve depression via affecting BDNF level. In this systematic review, for the first time, we aimed to review the effect of three SSRIs including fluoxetine, escitalopram, and sertraline, on both depression and BDNF level in preclinical and clinical studies. PubMed electronic database was searched, and 193 articles were included in this study. After reviewing all manuscripts, only one important difference was found: subjects. We found that SSRIs induce different effects in animals vs. humans. Preclinical studies showed many controversial effects, while human studies showed only two effects: improvement of depression, with or without the improvement of BDNF. However, most studies used chronic SSRIs treatment, while acute SSRIs were not effectively used and evaluated. In conclusion, it seems that SSRIs are reliable antidepressants, and the improvement effect of SSRIs on depression is not dependent to BDNF level (at least in human studies).

Comparing the diagnostic accuracy of MR dacryocystography (MRD) and dacryoscintigraphy (DSG) in NLDO-related acquired epiphora

PROPOSE

This study aimed to compare the diagnostic accuracy of MR dacryocystography (MRD) and dacryoscintigraphy (DSG) in the diagnosis of acquired epiphora related to NLDO. A total of 15 patients with acquired epiphora and suspected NLDO were included in this study.

METHODS

All patients underwent MRD and DSG examinations. MRD was performed using a 3-Tesla magnetic resonance imaging (MRI) scanner, while DSG involved injection of a radiotracer into the lacrimal drainage system followed by DSG. The results of both imaging methods were compared with the reference standard that was a combination of clinical examination findings and surgical exploration.

RESULTS

The results of this study showed that no abnormal findings were observed in MR-DCG in patients before the Valsalva maneuver. However, after the Valsalva maneuver, stenosis/obstruction at the canal surface was observed in all 15 patients diagnosed by DSG, giving a sensitivity of 100% for canal stenosis. Moreover, the results revealed that among these 15 patients, 9 showed stenosis or simultaneous obstruction at the level of the canal and lacrimal sac, but MR-DCG showed these lesions in only 9 patients, giving a sensitivity of 60%. The specificity of MRD and DSG were 85% and 76.7%, respectively. There was a statistically significant difference in the sensitivity of MRD and DSG (p < 0.05).

CONCLUSION

This study demonstrated that MRD has a higher diagnostic accuracy in the diagnosis of acquired epiphora associated with NLDO compared to DSG. MRD showed significantly higher sensitivity and specificity than DSG. Therefore, MRD can be considered as the preferred imaging modality in the diagnosis of acquired epiphora due to NLDO. By accurately identifying the underlying cause of NLDO, MRD can help determine the most appropriate treatment approach for patients and lead to better outcomes.

The correlation between echinoderms diversity and physicochemical parameters in marine pollution: A case study of the Persian Gulf coastline

This study was conducted with the aim of investigating the correlation between echinoderms diversity and physicochemical parameters in the Persian Gulf coastline in Bushehr province in 4 seasons from March to December 2017. The physicochemical parameters including water temperature, dissolved oxygen (DO), electrical conductivity (EC), salinity, pH and turbidity were measured at each sampling location. The results showed a significant correlation between echinoderms diversity and physicochemical parameters. The correlation coefficient of the Astropecten polyacanthus species with the parameters of temperature, DO, EC, salinity and turbidity was reported as -0.41, 0.64, -0.25, -0.44 and 0.60 respectively. This coefficient for the Ophiothrix fragilis species was reported as -0.68, 0.70, -0.21, -0.36 and -0.55 respectively. The results demonstrated that the most sensitive species were Astropecten polyacanthus and Ophiothrix fragilis respectively. The different species of echinoderms can be used as biological indicators of pollution in evaluating the physicochemical quality of marine environments.

Learning induces EPO/EPOr expression in memory relevant brain areas, whereas exogenously applied EPO promotes remote memory consolidation

Memory and learning allow animals to appropriate certain properties of nature with which they can navigate in it successfully. Memory is acquired slowly and consists of two major phases, a fragile early phase (short-term memory, <4 h) and a more robust and long-lasting late one (long-term memory, >4 h). Erythropoietin (EPO) prolongs memory from 24 to 72 h when animals are trained for 5 min in a place recognition task but not when training lasted 3 min (short-term memory). It is not known whether it promotes the formation of remote memory (≥21 days). We address whether the systemic administration of EPO can convert a short-term memory into a long-term remote memory, and the neural plasticity mechanisms involved. We evaluated the effect of training duration (3 or 5 min) on the expression of endogenous EPO and its receptor to shed light on the role of EPO in coordinating mechanisms of neural plasticity using a single-trial spatial learning test. We administered EPO 10 min post-training and evaluated memory after 24 h, 96 h, 15 days, or 21 days. We also determined the effect of EPO administered 10 min after training on the expression of arc and bdnf during retrieval at 24 h and 21 days. Data show that learning induces EPO/EPOr expression increase linked to memory extent, exogenous EPO prolongs memory up to 21 days; and prefrontal cortex bdnf expression at 24 h and in the hippocampus at 21 days, whereas arc expression increases at 21 days in the hippocampus and prefrontal cortex.

Improvement of Retinal Capillary Function After High-Speed Circuit Resistance Training in Healthy Older Adults

BACKGROUND

To determine the retinal capillary function (RCF, the efficiency of blood flow transferring in the capillary network) and its relation to cognitive function in healthy older people without known cognitive impairment following an 8-week high-speed circuit resistance training program (HSCT).

METHODS

Eleven subjects in the HSCT group and 7 age-matched nontraining controls (CON) were recruited. The HSCT group trained 3 times per week for 8 weeks, whereas CON performed no formal training. One eye of each subject from both groups was imaged at baseline and 8-week follow-up. Retinal blood flow (RBF) was measured using a retinal function imager, and retinal capillary density (RCD, expressed as fractal dimension Dbox) was measured using optical coherence tomography angiography. RCF was defined as the ratio of RBF to RCD. Cognitive function was assessed during both visits using the NIH Toolbox Fluid Cognition Battery.

RESULTS

RCF was 2.07 ± 0.64 nL⋅s -1 ·Dbox -1 (mean ± SD) at baseline, and significantly increased to 2.59 ± 0.54 nL⋅s -1 ·Dbox -1 after training ( P = 0.0003) in the HSCT group, reflecting an increase of 25%. The changes of RBF were not related to the changes of RCD in the HSCT group (r = -0.18, P = 0.59). There was no significant change of RCF in the CON group ( P = 0.58). In the HSCT group, the Pattern Comparison Processing Speed Test and Fluid Cognition Composite Score were significantly increased after HSCT ( P = 0.01). Furthermore, the changes in Flanker Inhibitory Control and Attention Test (FLNK) were positively correlated to increases in RCF (r = 0.77, P = 0.005).

CONCLUSIONS

This is the first prospective study to demonstrate that the increased RCF after HSCT was related to improved cognition in cognitively normal older adults.

The Interaction Effect of Sleep Deprivation and Treadmill Exercise in Various Durations on Spatial Memory with Respect to the Oxidative Status of Rats

Sleep deprivation (SD) has deleterious effects on cognitive functions including learning and memory. However, some studies have shown that SD can improve cognitive functions. Interestingly, treadmill exercise has both impairment and improvement effects on memory function. In this study, we aimed to investigate the effect of SD for 4 (short-term) and 24 (long-term) hours, and two protocols of treadmill exercise (mild short-term and moderate long-term) on spatial memory performance, and oxidative and antioxidant markers in the serum of rats. Morris Water Maze apparatus was used to assess spatial memory performance. Also, SD was done using gentle handling method. In addition, the serum level of catalase (CAT), superoxide dismutase (SOD), malondialdehyde (MDA), and glutathione peroxidase (GSH-Px) was measured. The results showed that 24 h SD (but not 4 h) had negative effect on spatial memory performance, decreased SOD, CAT, and GSH-Px level, and increased MDA level. Long-term moderate (but not short-term mild) treadmill exercise had also negative effect on spatial memory performance, decreased SOD, CAT, and GSH-Px level, and increased MDA level. Interestingly, both protocols of treadmill exercise reversed spatial memory impairment and oxidative stress induced by 24 h SD. In conclusion, it seems that SD and treadmill exercise interact with each other, and moderate long-term exercise can reverse the negative effects of long-term SD on memory and oxidative status; although, it disrupted memory function and increased oxidative stress by itself.

A Systematic Study into the Effects of Long-Term Multicomponent Training on the Cognitive Abilities of Older Adults with Neurodegenerative Disorders

Cognition includes all processes through which a person becomes aware of their situation, needs, goals, and necessary actions. Regular specialized cognitive and neuromotor simulation exercises have improved various cognitive processes, including memory, speed of reasoning, and problem-solving skills. This review focuses on understanding the efficacy of long-term multicomponent exercise interventions to mitigate and delay the effects on cognitive abilities in older adults with neurodegenerative disorders. The main criteria for final studies were randomised controlled trials with a minimum of a 24-week intervention. The Cochrane Central Register of Controlled Trials, Web of Science, SCOPUS, B-On, Sport Discus, Scielo, APA PsycINFO, Psychology and Behavioural Sciences, Academic Search Complete, Medline (PubMed), ERIC, and Google Scholar databases were checked. The search occurred between April 2022 and July 2022. A total of 19 studies were used in this review. The initial search identified 6.835 studies. In the first screening, a total of 6474 studies were excluded. After this, 361 studies were analysed by co-authors and did not meet the specific final criteria and were excluded. In total, 19 studies were included in the final analysis, and 14 papers met all requirements previously defined.

Effects of Aerobic Training on Brain Plasticity in Patients with Mild Cognitive Impairment: A Systematic Review of Randomized Controlled Trials

The purpose of this study was to systematically review to find if aerobic exercise compared to no exercise or any other intervention affects brain plasticity among people with mild cognitive impairment (MCI). Searches were conducted in the Scopus, SciELO, PubMed, Web of Science, Science Direct, and Google Scholar databases. The included studies were randomized control trials (RCTs) written in English comprising individuals with MCI that evaluated the effects of aerobic training on brain-derived neurotrophic factor (BDNF), brain structures, or brain activity. The quality of trials was evaluated using the PEDro scale for RCTs. Twelve studies with medium to high quality were included, of which five studies focused on brain-derived neurotrophic factor (four articles reported elevation and one article reported no changes in BDNF levels following the aerobic exercise), two studies focused on brain structures (both reported increases in hippocampus volume following the aerobic exercise), and five studies focused on brain activity (four articles reported positive changes, and one article reported no changes in brain activity following the aerobic exercise). Research regarding the effects of aerobic training on brain plasticity in people with MCI is in its infancy. Still, aerobic exercise seems to be a promising therapy in people with MCI.

Effects of Treadmill Exercise on Social Behavior in Rats Exposed to Thimerosal with Respect to the Hippocampal Level of GluN1, GluN2A, and GluN2B

Thimerosal (THIM) kills brain neurons via induction of apoptosis and necrosis and induces the pathological features of autism spectrum disorder (ASD) in rats. THIM also affects the function of glutamatergic receptors. On the other hand, exercise induces both improvement and impairment effects on memory, depending on intensity, type, and duration. Treadmill exercise can also alter the expression of glutamatergic receptors. In this study, we aimed to investigate the effect of THIM and three protocols of treadmill exercise on social interaction memory and hippocampal expression of GluN1, GluN2A, and GluN2B in rats. THIM was injected intramuscularly at the dose of 300 µg/kg. The three-chamber apparatus was used to evaluate social interaction memory, and western blotting was used to assess protein expression. The results showed that THIM impaired social memory. Exercise 1 impaired social affiliation in controls. Social memory was impaired in all exercise groups of controls. Exercise 1 + 2 impaired social affiliation in THIM rats. Social memory was impaired in all groups of THIM rats. Exercises 2 and 1 + 2 decreased the expression of GluN1, and exercise 1 increased the expression of GluN2A and GluN2B in controls. THIM increased the expression of GluN2B, while exercise 1 reversed this effect. All exercise protocols increased the expression of GluN2A, and exercises 2 and 1 + 2 increased the expression of GluN1 in THIM rats. In conclusion, both THIM and exercise impaired social memory. Of note, the results did not show a separate and influential role for glutamatergic subunits in modulating memory processes following THIM injection or exercise.