In the present study, we have examined the behavioral and biochemical effect of induction of psychological stress using a modified version of the resident-intruder model for social stress (social defeat). At the end of the social defeat protocol, body weights, food and water intake were recorded, depression and anxiety-like behaviors as well as learning-memory function was examined. Biochemical analysis including oxidative stress measurement, inflammatory markers and other molecular parameters, critical to behavioral effects were examined. We observed a significant decrease in the body weight in the socially defeated rats as compared to the controls. Furthermore, social defeat increased anxiety-like behavior and caused memory impairment in rats (P<0.05). Socially defeated rats made significantly more errors in long term memory tests (P<0.05) as compared to control rats. Furthermore, brain extracellular signal-regulated kinase-1/2 (ERK1/2), and an inflammatory marker, interleukin (IL)-6 were activated (P<0.05), while the protein levels of glyoxalase (GLO)-1, glutathione reductase (GSR)-1, calcium/calmodulin-dependent protein kinase type (CAMK)-IV, cAMP-response-element-binding protein (CREB) and brain-derived neurotrophic factor (BDNF) were significantly less (P<0.05) in the hippocampus, but not in the prefrontal cortex and amygdala of socially defeated rats, when compared to control rats. We suggest that social defeat stress alters ERK1/2, IL-6, GLO1, GSR1, CAMKIV, CREB, and BDNF levels in specific brain areas, leading to oxidative stress-induced anxiety-depression-like behaviors and as well as memory impairment in rats.
Diminished estrogen influence at menopause is reported to be associated with cognitive decline, heightened anxiety and hypertension. While estrogen therapy is often prescribed to overcome these behavioral and physiological deficits, antioxidants which have been shown beneficial are gaining nutritional intervention and popularity. Therefore, in the present study, utilizing the antioxidant properties of grapes, we have examined effect of 3 weeks of grape powder (GP; 15 g/L dissolved in tap water) treatment on anxiety-like behavior, learning-memory impairment and high blood pressure in ovariectomized (OVX) rats. Four groups of female Wistar rats were used; sham control, sham-GP treated, OVX and OVX+GP treated. We observed a significant increase in systolic and diastolic blood pressure in OVX rats as compared to sham-controls. Furthermore, ovariectomy increased anxiety-like behavior and caused learning and memory impairment in rats as compared to sham-controls. Interestingly, providing grape powder treated water to OVX rats restored both systolic and diastolic blood pressure, decreased anxiety-like behavior and improved memory function. Moreover, OVX rats exhibited an impaired long term potentiation which was restored with grape powder treatment. Furthermore, ovariectomy increased oxidative stress in the brain, serum and urine, selectively decreasing antioxidant enzyme, glyoxalase-1 protein expression in the hippocampus but not in the cortex and amygdala of OVX rats, while grape powder treatment reversed these effects. Other antioxidant enzyme levels, including manganese superoxide dismutase (SOD) and Cu/Zn SOD remained unchanged. We suggest that grape powder by regulating oxidative stress mechanisms exerts its protective effect on blood pressure, learning-memory and anxiety-like behavior. Our study is the first to examine behavioral, biochemical, physiological and electrophysiological outcome of estrogen depletion in rats and to test protective role of grape powder, all in the same study.
Previously, using the single-prolonged stress (SPS) rat model of post-traumatic stress disorder, we reported that moderate treadmill exercise, via modulation of oxidative stress related mechanisms, rescued anxiety and depression-like behaviors and reversed SPS-induced memory impairment. In this study using the SPS model (2 h restrain, 20 min forced swimming, 15 min rest, and 1–2 min diethyl ether exposure), we hypothesized that antioxidant rich grape powder (GP) prevents SPS-induced behavioral and memory impairment in rats. Male Sprague Dawley rats were randomly assigned into: Control (CON; provided tap water), SPS (provided tap water), GP-SPS (provided 15 g/L GP in tap water for 3 wk followed by SPS), or GP-CON (3 wk of GP followed by control exposure). Anxiety and depression-like behaviors were significantly greater in SPS rats when compared to CON or GP treated rats and GP reversed these behavioral deficits. SPS rats made significantly more errors in both short- and long-term memory tests compared to CON or GP treated rats, which were prevented in GP-SPS rats. GP prevented SPS-induced increase in plasma corticosterone level. Furthermore, brain derived neurotrophic factor (BDNF) levels were significantly decreased in amygdala of SPS rats but not in GP-SPS rats compared to CON or GP-CON rats. Additionally, GP significantly increased acetylated Histone3, Histone deacetylase 5 (HDAC 5) in hippocampus and amygdala of SPS rats as compared to CON or GP-CON rats. In conclusion, we suggest protective role of GP in SPS-induced behavioral, cognitive and biochemical impairments in rats. Perhaps, epigenetic regulation of BDNF enables GP-mediated prevention of SPS-induced deficits in rats.
Coronavirus Disease 2019 (COVID-19) is a contagious disease that affects the respiratory system. In addition to the severe effects of the disease on health, the pandemic caused a negative impact on basic needs and services, employment, education, and economy worldwide. In Jordan, the whole country locked down, and quarantine was enforced by the military forces, which successfully controlled the spread of the disease. This research aims to study the influence of the COVID-19 pandemic and its associated quarantine on university students' beliefs about online learning practice in Jordan. An online descriptive survey involved questions that covered students' demographic information, student's basic and advanced knowledge about COVID-19, students' online learning experience during the quarantine, and finally students' views on the enforced quarantine practice in Jordan. Results showed that students have a good knowledge (>50%) about the COVID-19 basic information and a moderate knowledge (<50%) regarding COVID-19 advanced information. In general, students were pessimistic about the future of COVID-19 both locally and worldwide. Although some students acknowledged that they learned new skills in the fields of electronics, informatics, and computer software during the pandemic, most of them were unsatisfied about the quality and quantity of the given material, online exams, and the evaluation processes. Unfortunately, most of the students faced internet technical problems or challenges to electronic accessibility. The majority of the participants (>90%) supported the military-enforced quarantine implemented in the country despite the hard time the students had during the quarantine. We conclude that university students were able to protect themselves from COVID-19 through their good knowledge about the infectious disease and their commitment to follow the rules imposed by the Government of Jordan. Nevertheless, the challenges caused by the pandemic and its associated quarantine, combined with the sudden unprecedented online experience, negatively impacted students' thoughts and beliefs about the online learning experience during the quarantine. Further studies need to be performed in this context. We hope our results will help decision-makers better understand the students' attitudes and motivation toward online learning and how this will affect their future plans and decisions.
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