Effect of PDGF and TGF-beta on the release of biogenic amines from invertebrate immunocytes and their possible role in the stress response

PDGF-AB and TGF-beta 1 intervene in molluscan stress response, the former inhibiting and the latter inducing the release of norepinephrine and epinephrine from hemocytes, These amines are down-regulated even when TGF-beta 1 is added to hemolymph pre-incubated with PDGF-AB, The opposite behaviour is observed if the growth factors are reversed. The dopamine response is not affected in either case, even after the addition of CRH or ACTH. After pre-incubation with PDGF-AB or TGF-beta 1 in the presence of CRH or ACTH, norepinephrine and epinephrine release falls, These findings suggest that when the interaction is between growth factors, the order of combination is crucial, while in cases where the interaction is between growth factors and other peptides, such as CRH and ACTH, the order is of no importance. (C) 1997 Federation of European Biochemical Societies.