Evidence for a form of adrenergic response to stress in the mollusc Crassostrea gigas.
Catecholamines and pro-opiomelanocortin (POMC)-derived peptides, some of the central regulators of the stress-response systems of vertebrates, are also present in invertebrates. However, studies are needed to determine how these hormones participate in the organisation of neuroendocrine stress-response axes in invertebrates. Our present work provides evidence for the presence of an adrenergic stress-response system in the oyster Crassostrea gigas. Noradrenaline and dopamine are released into the circulation in response to stress. Storage and release of these hormones take place in neurosecretory cells presenting morphological and biochemical similarities with vertebrate chromaffin cells. Both in vivo and in vitro experiments showed that applications of the neurotransmitters acetylcholine or carbachol caused no significant release of noradrenaline or dopamine. Moreover, the nicotinic antagonists hexamethonium and &agr; -bungarotoxin and the muscarinic antagonist atropine caused no significant inhibition of catecholamine release in stressed oysters. Adrenocorticotropic hormone (ACTH) induced a significant release of noradrenaline, but the release of dopamine in response to ACTH was not significant. These results suggest that, unlike that of vertebrates, the adrenergic stress-response system of oysters is not under the control of acetylcholine and that other factors, such as the neuropeptide ACTH, might control this system.
Lacoste
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A
Station Biologique de Roscoff, CNRS, INSU, Université Pierre et Marie Curie, Paris 6, BP 74, F-29682 ROSCOFF, France. lacoste@sb-roscoff.fr
Malham
S K
SK
Cueff
A
A
Jalabert
F
F
Gélébart
F
F
Poulet
S A
SA
D000109:Acetylcholine / Q000494:pharmacology; D000324:Adrenocorticotropic Hormone / Q000494:pharmacology; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D002038:Bungarotoxins / Q000494:pharmacology; D002217:Carbachol / Q000494:pharmacology; D018679:Cholinergic Agonists / Q000494:pharmacology; D019439:Chromaffin Cells / Q000166:cytology / Q000378:metabolism; D004298:Dopamine / Q000378:metabolism*; D006321:Heart / Q000187:drug effects / Q000502:physiology; D006458:Hemolymph / Q000737:chemistry; D018738:Hexamethonium / Q000494:pharmacology; D008856:Microscopy, Fluorescence; D018727:Muscarinic Antagonists / Q000494:pharmacology; D018733:Nicotinic Antagonists / Q000494:pharmacology; D009638:Norepinephrine / Q000378:metabolism*; D010125:Ostreidae / Q000502:physiology*; D014665:Vasodilator Agents / Q000494:pharmacology
D002038:Bungarotoxins; D018679:Cholinergic Agonists; D018727:Muscarinic Antagonists; D018733:Nicotinic Antagonists; D014665:Vasodilator Agents; D018738:Hexamethonium; D001285:Atropine; D002217:Carbachol; D000324:Adrenocorticotropic Hormone; D000109:Acetylcholine; D004298:Dopamine; D009638:Norepinephrine