ABSTRACT
High altitude (HA), defined as approximately 3000–5000 m, considerably alters physiological and psychological parameters within a few hours. Chronic HA-mediated hypoxia (5000 m) results in permanent neuronal damage to the human brain that persists for one year or longer, even after returning to sea level. At HA, there is a decrease in barometric pressure and a consequential reduction in the partial pressure of oxygen (PO2), an extreme environmental condition to which humans are occasionally exposed. This condition is referred to as hypobaric hypoxia (HBH), which represents the most unfavourable characteristics of HA. HBH causes the disruption of oxygen availability to tissue. However, no review article has explored the impact of HBH on cognitive functions or the potential therapeutic agents for HBH. Therefore, the present review aimed to describe the impact of HBH on both physiological and cognitive functions, specifically learning and memory. Finally, the potential therapeutic agents for the treatment of HBH-induced cognitive impairment are discussed.
ABSTRACT
Background: Depression is one of the common post-menopausal symptoms. In addition to estrogen deficiency, social instability stress may contribute as an additional underlying factor in the development of depressive behaviour in females. Therefore, this study was aimed at examining the influence of social instability stress on depressive behaviour in ovariectomized rats. Methods: The rats were divided into four groups (n = 5 per group); (i) sham-operated control without stress, (ii) sham-operated control with stress, (iii) ovariectomized without stress, and (iv) ovariectomized with stress. These rats were subjected to social instability stress procedures for 15 days prior to an enforced swimming test. Struggling, immobility, and swimming times were recorded promptly. Results: The results were analysed using the one-way analysis of variance (ANOVA) and a P value of < 0.05 was considered as significant. The mean durations of struggling, immobility, and swimming behaviour were significantly distinct among the four groups. Ovariectomized rats exhibited a substantial decrease in struggling and swimming behaviour, and an increase in immobility behaviour in comparison with the sham-operated controls (P < 0.05). Ovariectomized rats with stress displayed a supplementary decrease in struggling and swimming behaviour as well as an advanced increase in immobility behaviour, compared to sham-operated controls with or without stress (P < 0.05). Conclusion: In summary, these findings suggest that ovariectomized rats encountered an augmented amount of depressive behaviour following social instability stress.