Figure 1.
Serotonin (5-HT) protects mouse RBC from senescence in vitro.
Mouse RBC from WT or TPH1−/− mice were incubated at 4°C and their survival assessed by measuring hemolysis (A). Alternatively, mouse RBC from WT mice were incubated with increasing doses of 5-HT and their survival (B) and annexin V binding capacity (C) were evaluated. Data in each panel are presented as mean ± SEM of at least 4 independent experiments. In (C), *P<0.05; **P<0.01; ***P<0.001 when compared to value at day 0 in each group by one-way ANOVA and Dunnet’s post-hoc test.
Figure 2.
Serotonin (5-HT) protects mouse RBC from senescence in vivo.
Schematic diagram (left) of the transfer experiments conducted to evaluate the in vivo survival of WT RBC (right) in either a normal (WT, n = 12) or a 5-HT-depleted environment (TPH1−/−, n = 11). **P<0.01; ***P<0.001 by two-way ANOVA and Bonferroni’s post-hoc test.
Figure 3.
Serotonin (5-HT) precursors and agonists have no protective effect on mouse RBC in vitro.
Mouse RBC from WT mice were incubated at 4°C and their survival assessed by measuring hemolysis. The 5-HT precursors tryptophan, 5-hydroxytryptophan (5-HTP) or agonists for the 5-HT1A (8-OH DPAT), 5-HT1B/1D (GR 46611), 5-HT2 (PNU 22394), 5-HT4 (BIMU-8), 5-HT6 (WAY 208466) or the 5-HT7 receptors (LP-12) could not mimic the protective effect of 5-HT. All molecules were tested at a concentration of 100 µM. Data are presented as mean ± SEM of 3 independent experiments.
Table 1.
Mouse red blood cells do not express 5-HT receptors.
Figure 4.
Serotonin (5-HT) contributes to the antioxidant potential of plasma and its protective effect on RBC can be replicated by antioxidants.
Mouse RBC from WT mice were incubated at 4°C with the antioxidants trolox or melatonin and their survival assessed by measuring hemolysis (A). In (B), total antioxidant test was conducted on either normal (WT, n = 18) or 5-HT-deficient plasma (TPH1−/−, n = 17) to measure the plasma antioxidant capacity. Data are presented as mean ± SEM. ***P<0.001, by student t test.
Figure 5.
Serotonin (5-HT) supplementation improves 24h post-transfusion survival of RBC in a mouse model of blood banking.
Donor blood was collected in CPDA-1, leukoreduced and stored in sealed tubes in CPDA-1 supplemented or not with increasing doses of 5-HT. After storage, RBC were stained with CFDA-SE, transfused to recipient mice and their 24h post-transfusion survival was assessed by flow cytometry. Data are presented as mean ± SEM (n = 4–7). **P<0.01, ***P<0.001 by two-way ANOVA and Bonferroni’s post-hoc test.