Role of basal stress hormones and amygdala dimensions in stress coping strategies of male rhesus monkeys in response to a hazard-reward conflict

Environmental Effect of High-voltage Towers on the Cerebellum and Cognitive Impairments in the Monkey

Introduction

Today, high-voltage (HV) lines create a pernicious environment for humans living or working in the vicinity and even under these lines. The male rhesus monkey is used to investigate the effects of fields produced by HV towers. This study examines the function and level of impact in rhesus monkeys' brains from the cerebellum's cognitive, biological, and structural perspective.

Methods

Two monkeys have been used, one as a control and the second as a test. The monkey under test was subjected to a simulated HV electrical field of 3 kV/m, 4 hours a day, for 1 month. Behavioral tests were performed using a device designed and built for this purpose. Concentration analysis of adrenocorticotropic hormones (ACTH) and inspection of glucocorticoid receptor gene's (GR) expression were performed by the reverse transcription polymerase chain reaction method. Changes in cerebellar anatomy were examined with magnetic resonance imaging (MRI). All tests were performed before and after the study period and compared with the control monkey.

Results

Cognitive tests showed a significant reduction for the monkey exposed to the HV electrical field in the first week after imposition compared with the same time before. Also, the expression of the GR gene decreased, and the concentration of ACTH hormone in plasma increased. Surveying the level of cerebral MRI images did not show any difference, but hemorrhage was evident in a part of the cerebellum.

Conclusion

The tested monkey's cognitive, biological, and MRI results showed a decrease in visual learning and memory indices.

Evaluation of Stress and Cognition Indicators in a Puzzle Game: Neuropsychological, Biochemical and Electrophysiological Approaches

Video games have significant and diverse effects on stress and cognitive systems based on the game style. The effect of this media on the central nervous system is significant because of its repetition. Nowadays, video games have become an important part of human life at different ages, and therefore, assessing their effects (good and bad) on stress factors, cognition, and behavior can be an important help in understanding the nature of these games and managing their impact on humans. Consequently, this study aimed to investigate the effect of a puzzle game on the player's stress and cognitive indicators in neuropsychological, biochemical, and electrophysiological approaches. A total of 44 participants were entered into the study and randomly assigned to control and experimental groups. Our interventions were watching (control group) and playing (experimental group) the game. Salivary biomarkers (cortisol and alpha-amylase) were measured using the enzyme-linked immunosorbent assay method. Electrophysiological assessment of attention and stress was performed using electroencephalography. Neuropsychological assessments for the evaluation of mental health, mental fatigue, sustained attention, and reaction time were conducted using paced auditory serial addition test. All tests were administered before and after the interventions. The findings revealed that the salivary cortisol and alpha-amylase significantly reduced after playing the game. There were significantly higher levels of attention after playing the game. Mental health and sustained attention significantly increased after game playing. It can conclude that puzzle-style computer games can strengthen and empower the perceptual-cognitive system and suppress the stress system of players. Therefore, they can be used purposefully as a positive cognitive therapy approach.

Improvement of Cognitive Indicators in Male Monkeys Exposed to Extremely Low-Frequency Electromagnetic Fields

Today, the production of extremely low-frequency electromagnetic fields (ELF-EMFs) has significantly increased. This study aimed to investigate the effect of the ELF-EMFs on the structure and function of the brain in male rhesus monkeys in terms of visual learning (VL), visual memory (VM), and visual working memory (VWM). To conduct the study, four monkeys were selected, of whom two monkeys were irradiated by 12-Hz ELF-EMFs with a magnitude of 0.7 microtesla, and two monkeys were tested without irradiation (control group). A blood sample was taken in three stages, namely pre- and post-irradiated and the recovery phases. Changes in the plasma levels of sodium, potassium, and adrenocorticotropic hormone (ACTH) were evaluated. Moreover, gene expression of N-methyl-D-aspartate (NMDA) receptors was assessed. The anatomical change of the brain's prefrontal area was measured by magnetic resonance imaging and Digital Imaging and Communications in Medicine LiteBox file. The abilities of VL, VM, and VWM significantly improved after the irradiation. Furthermore, the expression of the NMDA receptors gene and the plasma levels of sodium, potassium, and ACTH significantly enhanced after the irradiation. However, the prefrontal area was not significantly affected by the irradiation. No significant differences were observed in any of the studied factors in the control group. Our findings suggested that ELF-EMFs irradiation at 12 Hz positively affected VL and VWM. Consequently, 12-Hz ELF-EMFs irradiations can be widely applied to improve cognitive abilities in monkeys.

The Effect of 12 Hz Extremely Low-frequency Electromagnetic Field on Visual Memory of Male Macaque Monkeys

Introduction

Today, humans live in a world surrounded by electromagnetic fields. Numerous studies have been conducted to discover the biological, physiological, and behavioral effects of electromagnetic fields on humans and animals. Given the biological similarities between monkeys and humans, The present research aimed to examine Visual Memory (VM), hormonal, genomic, and anatomic changes, in the male rhesus macaques exposed to an Extremely Low-Frequency Magnetic Field (ELF-MF).

Methods

Four male rhesus macaques (Macaca mulatta) were used. For the behavioral tests, the animals should be fasting for 17 hours. For the tests such as visual memory, the animal's cooperation was necessary. Using the radiation protocol, we exposed two monkeys to a 12-Hz electromagnetic field with a magnitude of 0.7 μT (electromagnetic radiation) four hours a day for a month. Before and after the exposure, a visual memory test was conducted using a coated device (visible reward) on a movable stand. Ten milliliters of blood was obtained from the femoral artery of each monkey, and half of it was used to examine cortisol serum levels using the MyBioSource kit (made in the USA). The other half of the blood was used to extract lymphocytes for assaying expressions of Glucocorticoid Receptor (GR) genes before and after radiation using the PCR method. Anatomic studies of the amygdala were carried out based on pre- and post-radiation Magnetic Resonance Imaging (MRI).

Results

Research results indicated that visual memory in male primates increased significantly after exposure to the 12-Hz frequency. Hormonal analysis at the 12-Hz frequency showed a decrease in cortisol serum levels. However, visual memory and serum cortisol levels did not change considerably in male primates in the control group. There was no considerable amygdala volumetric difference after exposure to the 12-Hz frequency. The expression of the GR genes decreased in the 12-Hz group compared to the control group.

Conclusion

In short, these results indicated that ELF might benefit memory enhancement because exposure to the 12-HZ ELF can enhance visual memory. This outcome may be due to a decrease in plasma cortisol and or expression of GR genes. Moreover, direct amygdala involvement in this regard cannot be recommended.

Highlights

The effects of Extremely Low-Frequency Electromagnetic Fields (ELF-EMF) of 12 Hz on monkeys were studied.The results showed a reduction in the serum cortisol levels and the expression of GR genes.The amygdala anatomical area changes were not significant in the experimental group.In the experimental group, visual memory (delay of 30- and 60-s evaluation) improved after exposure to a frequency of 12 Hz.

Plain Language Summary

Extremely low-frequency electromagnetic fields are among the most important factors affecting humans. This study aimed to determine the fields of 12-Hz frequency on the visual memory changes of male monkeys. The importance of research is due to the cognitive similarity of monkeys to humans. The findings of the research can be attributed to humans. Behavioral, hormonal, genetic, and anatomical studies indicated improvement in visual memory (test monkeys versus control monkeys). This study demonstrates the effect of the 12-Hz frequency on the monkey's visual memory. Researchers can study 12-Hz frequency in other cognitive indices.

The Effect of Electrical Fields From High-voltage Transmission Line on Cognitive, Biological, and Anatomical Changes in Male Rhesus macaque Monkeys Using MRI: A Case Report Study

Introduction

Living near high-voltage power lines and exposure to high-frequency electromagnetic fields (EMFs) is a potentially serious hazard to animal and human health. The present study was conducted to evaluate the effect of high-frequency EMFs from simulated high-voltage electric towers on cognitive, anatomical, and biological changes in the male macaque.

Methods

In this study, two Rhesus macaque were recruited, one experimental and one control. The experimental subject was exposed to EMFs from 3 kV/m simulated electric towers with a specific protocol and the control subject was tested without irradiation (4h per day, for 30 days). All required tests were performed before and after the intervention on experimental and control monkeys. The anatomical alternation of the prefrontal area (PFA) was measured by MRI images. All tests were performed on irradiated and control animals before and after the intervention and the results were compared between irradiated and control animals.

Results

The results of the present study indicated increased white blood cell counts after high-frequency EMFs irradiation. Also, the red blood cell counts showed a decreasing trend after irradiation. The plasma adrenaline level increased after irradiation. Besides, the blood glucose levels increased after irradiation. The PFA was different before and after the irradiation. Moreover, some behavioral disorders, such as fatigue, drowsiness, anorexia, and insomnia were observed after irradiation.

Conclusion

The results of biological tests and MRI showed an elevated risk of immunodeficiency disorders, weakness, and behavioral disorders. People who live or work near high-voltage electric towers with high-frequency EMFs are warned.

Highlights

Magnetic, and electric fields from high pressure towers caused negative effects in terms of biology and even anatomical changes in the prefrontal part of the brain.Disturbance in the prefrontal part of the brain caused the monkey's cognitive and behavioral disorder.An increase in white blood cells, a decrease in red blood cells, and an increase in the adrenaline and blood sugar were indicative of biological disorders after wave exposure in male rhesus monkeys.The effects of magnetic and electric fields resulting from high pressure towers on the nerves and psyche require health researchers to do more studies.

Plain Language Summary

Today, one of the factors that threaten the cognitive and behavioral health of humans and animals is living in the vicinity of magnetic and electric fields resulting from the power transmission of high-pressure towers. These fields cause cognitive and behavioral disorders in living beings. Therefore, because it threatens the cognitive health of creatures, it needs more research.

Rubrofusarin Attenuates Chronic Restraint Stress-Induced Depressive Symptoms

The aim of this study was to examine whether rubrofusarin, an active ingredient of the Cassia species, has an antidepressive effect in chronic restraint stress (CRS) mouse model. Although acute treatment using rubrofusarin failed, chronic treatment using rubrofusarin ameliorated CRS-induced depressive symptoms. Rubrofusarin treatment significantly reduced the number of Fluoro-Jade B-positive cells and caspase-3 activation within the hippocampus of CRS-treated mice. Moreover, rubrofusarin treatment significantly increased the number of newborn neurons in the hippocampus of CRS-treated mice. CRS induced activation of glycogen synthase kinase-3β and regulated development and DNA damage responses, and reductions in the extracellular-signal-regulated kinase pathway activity were also reversed by rubrofusarin treatment. Microglial activation and inflammasome markers, including nod-like receptor family pyrin domain containing 3 and adaptor protein apoptosis-associated speck-like protein containing CARD, which were induced by CRS, were ameliorated by rubrofusarin. Synaptic plasticity dysfunction within the hippocampus was also rescued by rubrofusarin treatment. Within in vitro experiments, rubrofusarin blocked corticosterone-induced long-term potentiation impairments. These were blocked by LY294002, which is an Akt inhibitor. Finally, we found that the antidepressant effects of rubrofusarin were blocked by an intracerebroventricular injection of LY294002. These results suggest that rubrofusarin ameliorated CRS-induced depressive symptoms through PI3K/Akt signaling.

Effects of the Extremely Low Frequency Electromagnetic Fields on NMDA-Receptor Gene Expression and Visual Working Memory in Male Rhesus Macaques

Introduction

The present research aimed to examine Visual Working Memory (VWM) test scores, as well as hormonal, genomic, and brain anatomic changes in the male rhesus macaques exposed to Extremely Low Frequency Magnetic Field (ELF-MF).

Methods

Four monkeys were exposed to two different ELF-MF frequencies: 1 Hz (control) and 12 Hz (experiment) with 0.7 μT (magnitude) 4 h/d for 30 consecutive days. Before and after the exposure, VWM test was conducted using a coated devise on a movable stand. About 10 mL of the animals' blood was obtained from their femoral vain and used to evaluate their melatonin concentration. Blood lymphocytes were used for assaying the expressions of N-Methyl-D-aspartate NMDA-receptor genes expression before and after ELF exposure. Anatomical changes of hippocampus size were also assessed using MRI images.

Results

Results indicated that VWM scores in primates exposed to 12 Hz frequency ELF increased significantly. Plasma melatonin level was also increased in these animals. However, these variables did not change in the animals exposed to 1 Hz ELF. At last, expression of the NMDA receptors increased at exposure to 12 Hz frequency. However, hippocampal volume did not increase significantly in the animals exposed to both frequencies.

Conclusion

In short, these results indicate that ELF (12 Hz) may have a beneficial value for memory enhancement (indicated by the increase in VWM scores). This may be due to an increase in plasma melatonin and or expression of NMDA glutamate receptors. However, direct involvement of the hippocampus in this process needs more research.