A. Lacoste et al., Noradrenaline reduces the stimulatory effect of interleukin-1 alpha on reactive oxygen species production by oyster immunocytes, INVERTEBR B, 120(4), 2001, pp. 358-364
A growing body of evidence suggests that interleukin-1 alpha (IL-1 alpha) i
s present in invertebrates. Both invertebrate and human IL-1 alpha can bind
to invertebrate receptors and stimulate invertebrate immune functions. The
present study shows that IL-1 alpha increases reactive oxygen species (ROS
) production by oyster immunocytes. However, physiological doses of noradre
naline (NA) exert a suppressive effect on IL-1 alpha stimulation in vitro.
The beta -adrenoceptor agonist isoproterenol mimicked the effects of NA and
the beta -adrenoceptor antagonist propanolol blocked the NA-induced suppre
ssion of hemocyte responsiveness to IL-1 alpha. The type IV phosphodiestera
se inhibitor rolipram acted in synergy with isoproterenol to reduce hemocyt
e response to IL-1 alpha and the protein kinase A inhibitor H-89 suppressed
the effects of isoproterenol. These results suggest that circulating NA im
pairs IL-1 alpha -stimulation of oyster hemocyte via a beta -adrenoceptor/c
yclic AMP/protein kinase-A signaling pathway. Considering that mollusc immu
nocytes secrete NA, an autocrine regulatory loop may also modulate the abil
ity of these cells to respond to IL-1 alpha.