Chronic stress influence in panic development during scuba-diving practice: a pre-clinical study

Abstract

Background: The investigation of SCUBA-diving fatalities is performed in a multidisciplinary team to elucidate the cause of death and the sequence of events that led to the fatality. This is performed determining: triggering factor, disabling agent, disabling injury and cause of death. Panic is reported as one of the most common triggering factors (40-60%) specially in arterial gas embolism following pulmonary barotrauma (PBt/AGE) deaths that performed a rapid ascend even in experienced divers. Chronic stress has been observed as a risk factor on the development of panic and therefore loss of control when a hazardous or unpredicted situation appears. This situation can lead to a reactive maladaptive behaviour and the diver, even knowing that it can be lethal, performs a rapid ascent. Objective: To determine if chronic-stress impairs decision-making behaviour through a SCUBA-diving-like model, assessing rats behaviour after an underwater threatening situation and determining stress-related biomarkers (MAOA and CHRH1) in the prefrontal cortex and amygdala. Methodology: the preclinical study has three phases. First, rats will be trained to perform a SCUBA-diving test, consisting of an acquisition task (ACQ) followed by a retention (RT) test. In the second phase rats will be divided in two groups and one of them will be exposed to chronic unpredictable stress (CUS) protocol. Finally, in the third phase, both groups will be exposed to SCUBA-diving test under threatening situation (water trauma; UWT) to assess their under-water choice-making behaviour. At the end, qPCR will be used to assess MAOA and CHRH1 mRNA expression as biomarkers of underwater impaired choice-making behaviour