Acute Restraint Stress in Zebrafish: Behavioral Parameters and Purinergic Signaling

Abstract

Despite the extensive knowledge about the effects of acute restraint stress (ARS) in rodents, zebrafish research is still elementary in this field, and the consequences of stress on purinergic system are unclear. Therefore, we evaluated the effects of ARS on behavior, biochemical, and molecular parameters in zebrafish brain. Animals were submitted to a 90 min ARS protocol and tested for anxiety levels, exploratory behavior, and memory performance. Furthermore, we analyzed ectonucleotidase and adenosine deaminase activities and their gene expression profile, as well as transcription of adenosine receptors. ARS increased anxiety, but did not impair locomotion or cognition. ARS significantly increased ATP hydrolysis, decreased cytosolic ADA activity, and changed the entpd and adora gene expression. In conclusion, ARS disturbed zebrafish behavior, and we hypothesize that the augmentation in adenosine-mediated signaling may be a strategy to reestablish homeostasis and normal behavior after a stressful event.

Unpredictable Chronic Stress Alters Adenosine Metabolism in Zebrafish Brain

“…Meanwhile, the same stress protocol was able to induce an increase on ATP hydrolysis, without changes in the ADP or AMP hydrolysis in rat hippocampal synaptosomes [57]. Piato and colleagues [18] showed that acute restraint stress significantly increased ATP hydrolysis, decreased cytosolic ADA activity, and altered the entpd and adora gene expression. In our study, there were no significant changes on ectonucleotidase activities (NTPDase and ecto-5′-nucleotidase) after the exposure to UCS protocol in zebrafish brain.…”

“…UCS changes brain physiology and neural circuits [14] and leads to the development of depressive behaviors [15]. In mammalians, the hypothalamic-pituitary-adrenal (HPA) axis and the sympathetic nervous system (SNS) have a major role on physiological stress response in the body and constitute the main effector pathways of the stress system, mediating their adaptive functions [3,16] Zebrafish is a helpful model organism to evaluate stress and anxiety [17][18][19][20] and is useful for assessing behavioral and molecular mechanisms of brain disorders [21][22][23], developmental biology, pathophysiology of metabolic diseases, and neurodegeneration [24][25][26][27]. There is a high degree of homology between zebrafish and humans, as the presence of a homologue of the HPA axis, the hypothalamic-pituitary-interrenal axis (HPI).…”

“…Evidence demonstrated that adenosine receptors may be altered during chronic stress [41,42], and changes in the concentrations of extracellular ATP [43] and adenosine in rodents [44] have also been observed after exposure to stressors. Studies have already demonstrated that acute restraint stress altered ADA activities in zebrafish brain [18]. However, the relationship between chronic stress and its effects on purinergic signaling in zebrafish is limited.…”

Adenosine enhances progenitor cell recruitment and nerve growth via its A2B receptor during adult fin regeneration

“…Recent studies showed that acute restraint stress enhanced ROS production in the brain [42] and modified purinergic signalling in adult fish [43]. Considering that caudal fin amputation triggers ROS production which is essential for regeneration [10], we decided to test directly whether the purinergic signalling engaged by apoptotic cells during adult caudal fin regeneration is of importance for cell plasticity, i.e.…”

“…S1). Four adenosine receptor (AdoR) subtypes (A1, A2A, A2B and A3) and two transporters (ENT1 and 2) have been identified in vertebrates [46] and the subtypes A1 [43] as well as A2A and B [47] studied in zebrafish [41]. After caudal fin amputation, the fish were incubated in agonists or an antagonist of AdoR, and the size of the regenerate was analysed at 3 dpa (Fig.…”