Effect of β-adrenergic antagonists on bioluminescence control in three species of brittlestars (Echinodermata: Ophiuroidea)

The role of adrenaline in the nervous control of bioluminescence in three brittlestar species, Amphiura filiformis, Amphipholis squamata, and Ophiopsila aranea, was assessed by testing two different β-adrenergic antagonists (propranolol and labetalol) over a wide concentration range (10-10–10-3M). We compared the effects of analogues (active vs. inactive) of the same substance (l- and d-enantiomers of propranolol). Propranolol presented both specific and nonspecific effects: (i) nonspecific effects were observed at the higher concentrations tested (10-4 and 10-3M) in all three species; (ii) specific effects were detected only at the lower concentrations tested (10-6–10-5M). In A. squamata, the involvement of adrenaline in the nervous control of luminescence is supported by propranolol and labetolol specific inhibition. The neuropharmacological implications of nonspecific effects, the involvement of adrenaline and the interspecific differences in the brittlestar nervous control of bioluminescence are discussed. [Copyright &y& Elsevier]