The respiratory burst of rainbow trout, Oncorhynchus mykiss (Walbaum), phagocytes is modulated by sympathetic neurotransmitters and the neuro peptide ACTH

The phagocytic leukocytes of teleosts, like those of many animal groups, are capable of converting molecular oxygen to a series of highly reactive oxygen intermediates. These constitute part of the cytotoxic defences of the animal. Reactive oxygen intermediates produced in vitro by rainbow trout, Oncorhynchus mykiss , pronephric myeloid cells have been detected by means of luminol-enhanced chemiluminescence, and by the reduction of cytochrome c in the presence and absence of exogenous superoxide dismutase and catalase. A panel of potential biological response modifiers, when added individually to cell suspensions, showed that the catecholamine receptor agonists phenylephrine and isoproterenol differentially modulate the respiratory burst. Receptor antagonists yohimbine, phentolamine and prazosin showed that the effects were receptor-mediated. Adrenocorticotropin (ACTH) enhanced the apparent respiratory burst in both assays. Pathways of neuroimmunological regulation, therefore, include non-lymphoid cells as targets of classical neurotransmitters and a neurohormone.