Neuroendocrinology and neuroimmunology of stress in an invertebrate model, the oyster Crassostrea gigas
In invertebrates, the immune and neuroendocrine systems communicate and interact via diverse cytokines and hormones. Thus, both systems constitute an integrated network allowing the organism to elicit neuroendocrine as well as immune responses to both cognitive and non-cognitive stimuli. This neuro-...
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| Other Authors: | , , , , |
| Format: | Doctoral or Postdoctoral Thesis |
| Language: | French |
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HAL CCSD
2001
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| Subjects: | |
| Online Access: | https://hal.sorbonne-universite.fr/tel-01117505 https://hal.sorbonne-universite.fr/tel-01117505/document https://hal.sorbonne-universite.fr/tel-01117505/file/lacoste.pdf |
| Summary: | In invertebrates, the immune and neuroendocrine systems communicate and interact via diverse cytokines and hormones. Thus, both systems constitute an integrated network allowing the organism to elicit neuroendocrine as well as immune responses to both cognitive and non-cognitive stimuli. This neuro-immune system axis plays essential roles in the maintenance of homeostasis, particularly when the animal faces stressful situations. The present work aimed at providing further knowledge concerning the evolutionary origins of these adaptative mechanisms by studying neuroendocrinology and neuroimmunlogy of stress in an invertebrate model.Our biological model was chosen among molluscs because these organisms possess a relatively immune system and because their nervous system is well characterized at the functional, cellular and molecular levels. Among molluscs, we focused on the Pacific oyster Crassostrea gigas because this bivalve is of economical interest and because research on the physiology of stress in oysters can be directly applied in aquaculture. We provide evidence that oysters possess a form of neuroendocrine response to stress. Indeed, two catecholamines, namely noradrenaline and dopamine, are released in the hemolymph when the animal encounters stressful situations. Oyster catecholamine-secreting cells possess morphological, biochemical and functional characteristics of vertebrate chromaffin cells. Moreover, these cells exhibit a remarkable plasticity since they can transdifferentiate into either neuron-like or glial-like cells.Noradrenaline produced bu chromaffin cells modulate certain immune functions such as the production of reactive oxygen species and phagocytosis. This catecholamine can also trigger hemocyte apoptosis and/or upregulate the transcription of the heat stress protein 70 (hsp70) gene in immune cells. These mechanisms involve α and β-adrenergic receptors, GTPases of the Ras family such as Rho, MAP kinases and P35-sensitive caspases. Finally, we found that stress and stress-induced ... |
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