Figure 3
Survival of neurons pre-cultured for 4 days followed by 2 days of culture in the absence (▲) or presence of mast cells (■, indicated by horizontal bar in each graph). During the co-culture period the effects of GLP1, GLP2 and VIP (10-9- 10-6 M), in the absence or presence of GLP1 receptor antagonist (exendin(9-39)amide, 10-7 M) or VIP receptor antagonist (hybVIP, 10-7 M), on neuronal survival were determined by neuronal cell counting. With increasing concentrations all three peptides were able to reverse mast cell-induced neuronal cell death (denoted ns; no significant difference). Simultaneous presence of exendin(9-39)amide (10-7 M) counteracted the effects of GLP1 while GLP2- or VIP-induced neuroprotection was unaffected. Addition of hybVIP (10-9 M) to the co-cultures hampered GLP1- and VIP-, but not GLP2-, induced neuroprotection. Means ± SEM, n = 5-12; ns, no significant difference; * p < 0.1; ** p < 0.05; *** p < 0.01 as compared to controls run in parallel (▲) without addition of mast cells, peptides or antagonists.