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Bosco G, Giacon TA, Paolocci N, Vezzoli A, Noce CD, Paganini M, Agrimi J, Garetto G, Cialoni D, D'Alessandro N, Camporesi EM, Mrakic-Sposta S. Dopamine/BDNF loss underscores narcosis cognitive impairment in divers: a proof of concept in a dry condition. Eur J Appl Physiol 2023; 123:143-158. [PMID: 36214902 DOI: 10.1007/s00421-022-05055-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2022] [Accepted: 09/18/2022] [Indexed: 01/20/2023]
Abstract
PURPOSE Divers can experience cognitive impairment due to inert gas narcosis (IGN) at depth. Brain-derived neurotrophic factor (BDNF) rules neuronal connectivity/metabolism to maintain cognitive function and protect tissues against oxidative stress (OxS). Dopamine and glutamate enhance BDNF bioavailability. Thus, we hypothesized that lower circulating BDNF levels (via lessened dopamine and/or glutamate release) underpin IGN in divers, while testing if BDNF loss is associated with increased OxS. METHODS To mimic IGN, we administered a deep narcosis test via a dry dive test (DDT) at 48 msw in a multiplace hyperbaric chamber to six well-trained divers. We collected: (1) saliva samples before DDT (T0), 25 msw (descending, T1), 48 msw (depth, T2), 25 msw (ascending, T3), 10 min after decompression (T4) to dopamine and/or reactive oxygen species (ROS) levels; (2) blood and urine samples at T0 and T4 for OxS too. We administered cognitive tests at T0, T2, and re-evaluated the divers at T4. RESULTS At 48 msw, all subjects experienced IGN, as revealed by the cognitive test failure. Dopamine and total antioxidant capacity (TAC) reached a nadir at T2 when ROS emission was maximal. At decompression (T4), a marked drop of BDNF/glutamate content was evidenced, coinciding with a persisting decline in dopamine and cognitive capacity. CONCLUSIONS Divers encounter IGN at - 48 msw, exhibiting a marked loss in circulating dopamine levels, likely accounting for BDNF-dependent impairment of mental capacity and heightened OxS. The decline in dopamine and BDNF appears to persist at decompression; thus, boosting dopamine/BDNF signaling via pharmacological or other intervention types might attenuate IGN in deep dives.
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Affiliation(s)
- Gerardo Bosco
- Department of Biomedical Sciences, University of Padova, 35131, Padova, Italy
- Division of Cardiology, Johns Hopkins Medical Institutions, Baltimore, MD, USA
- Institute of Clinical Physiology, National Research Council (CNR), 20162, Milano, Italy
- ATIP Center for Hyperbaric Medicine, Padova, Italy
| | | | - Nazareno Paolocci
- Department of Biomedical Sciences, University of Padova, 35131, Padova, Italy
- Division of Cardiology, Johns Hopkins Medical Institutions, Baltimore, MD, USA
| | - Alessandra Vezzoli
- Institute of Clinical Physiology, National Research Council (CNR), 20162, Milano, Italy
| | - Cinzia Della Noce
- Institute of Clinical Physiology, National Research Council (CNR), 20162, Milano, Italy
| | - Matteo Paganini
- Department of Biomedical Sciences, University of Padova, 35131, Padova, Italy
| | - Jacopo Agrimi
- Division of Cardiology, Johns Hopkins Medical Institutions, Baltimore, MD, USA
| | | | - Danilo Cialoni
- Department of Biomedical Sciences, University of Padova, 35131, Padova, Italy
- Division of Cardiology, Johns Hopkins Medical Institutions, Baltimore, MD, USA
- Institute of Clinical Physiology, National Research Council (CNR), 20162, Milano, Italy
- ATIP Center for Hyperbaric Medicine, Padova, Italy
- Dan Europe Foundation, Research Division, Roseto degli Abbruzzi, Teramo, Italy
| | | | | | - Simona Mrakic-Sposta
- Institute of Clinical Physiology, National Research Council (CNR), 20162, Milano, Italy.
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