A NOVEL ACTION OF ANGIOTENSIN PEPTIDES IN INHIBITING NEURITE OUTGROWTH FROM ISOLATED CHICK SYMPATHETIC NEURONS IN CULTURE

There is increasing evidence that neuropeptides have trophic functions during embryogenesis. We examined the ability of angiotensin II, subs tance P, somatostatin-28 and luteinising hormone-releasing hormone to influence neurite outgrowth from embryonic chick sympathetic neurons i n culture. Nanomolar concentrations of angiotensin II inhibited neurit e outgrowth, whereas the other peptides had no effect at similar conce ntrations. The effect of angiotensin II on neurite outgrowth is likely to be mediated by an atypical angiotensin receptor, as it was only we akly inhibited by [sar(1),ala(8)]angiotensin II, and was not inhibited by losartan, an inhibitor of mammalian AT(1) receptors, or PD123319, an AT(2) inhibitor. Neurite outgrowth was also inhibited by angiotensi n III and angiotensin IV but not by angiotensinogen I-1-14. The study provides further evidence that angiotensin peptides, like classical ne urotransmitters, may have trophic functions during embryogenesis.