Effects of electrical lesion of basolateral amygdala nucleus on rat anxiety‐like behaviour under acute, sub‐chronic, and chronic stresses

Abstract

Stress contributes, as a risk factor, to such psychological disorders as anxiety. The effects of electrical lesions in the basolateral amygdala nucleus (BLA) were investigated on the locomotor activity and anxiety-like behaviour in different stress durations. For this purpose, rats were randomly allocated to control, sham, and experimental groups, the latter including groups with and without BLA nucleus subjected to acute, sub-chronic, and chronic stress conditions for 1, 7, and 21 days, respectively, applied 6 h/d. The induced anxiety behaviour was evaluated using the open field test (OFT) while other variables were measured. Findings revealed that sub-chronic stress led to significantly reduced (P<.05) anxiety behaviours as measured by entries into and the time spent in the centre area while it also led to significant impairments in exploratory and locomotor activities, indicating intensified anxiety-like behaviour. BLA lesion affected rat behaviour differently such that it significantly (P<.05) decreased fear under sub-chronic and chronic stress conditions as evidenced by the subjects' greater tendency to enter the centre area in the open field test and their increased number of rearing events (P<.01). However, BLA lesion led to no significant decrease in the locomotor activity of subjects exposed to sub-chronic or chronic stress conditions as compared with those in similar groups but without BLA lesion. Finally, BLA lesion was found not only to decrease significantly (P<.01) adrenal gland and body weights, particularly under sub-chronic stress, but also to play a critical role in modulating adrenal functions by decreasing adrenal gland weight, and thereby reducing depression-like symptoms.

Effects of Crocin on Learning and Memory in Rats Under Chronic Restraint Stress with Special Focus on the Hippocampal and Frontal Cortex Corticosterone Levels

“…The findings confirm the hypothesis that chronic stress is accompanied by a disturbance in STL as memory. It has been shown that chronic restraint stress impairs brain functions and memory processing in rats,[ 2 30 31 32 33 ] whereas it also alters such neuronal properties as suppression of neurogenesis in the dentate gyrus of the hippocampus[ 34 35 36 ] and changes the emotional and stress-related responses in animals. [ 2 30 ] Various mechanisms are involved in the stress responses; these include changes in stress biomarkers, hormones, and neurotransmitters as well as free radical generation and anti-oxidant enzyme activities.…”

Effects of Isolation and Social Subchronic Stresses on Food Intake and Levels of Leptin, Ghrelin, and Glucose in Male Rats

“…Moreover, they proposed that there were more changes in subchronic restraint stress on BWD. [17] Collectively, the findings of the current and previous studies suggested that stress duration (even with different kinds of stress) is the main factor that affects the BWD. In addition, it is proposed that the subchronic stress corresponds to the alternation of food intake responses similar to acute stress and reduces food intake and body weight.…”

“…They demonstrated that subchronic stress (7 days) has the most deleterious emotional stress. [121617] In this regard, previous studies also have shown that acute stress is associated with the reduction of food intake,[439] while chronic stress increases the food consumption. [40] Moreover, it seems that changes of food intake are related to the stressor's characteristics such as type stress, duration of stress, the intensity of stress, and the individual's stress characteristics, metabolic state, and dietary in stress condition.…”

“…[1314] Based on the stress duration category, a variety of acute, subchronic, and chronic stress exists. [1115161718] Acute stress suppresses the appetite as an instant physiological response. [4] While, seeking out and eating happens in the chronic stress situations.…”

Short-term environmental enrichment induces ‘resilience to chronic stress’ in adulthood (A study traversing behavioural, neuronal and molecular plasticity in brain)

“…consecutive days) and chronic (stress exposure for 21 consecutive days) stress in rodents which confirms that anxiety behaviour induced by chronic stress is in fact mediated by the BLA [217]. Besides this, Section 2.3.2 C also mentions various studies which elaborate on how molecules such as GAD, GR and BDNF in the BLA are essentially involved in mediating fear responses are affected by stress.…”