OBJECTIVETo explore the influence of exogenous putrescine and cadaverine on pro-inflammatory factors in the peripheral blood of rabbits.

METHODSForty ordinary adult New Zealand rabbits were divided into saline, necrotic tissue homogenate (NTH), putrescine, and cadaverine groups according to the random number table, with 10 rabbits in each group. Saline, NTH, 10 g/L putrescine, and 10 g/L cadaverine were respectively peritoneally injected into rabbits of corresponding group in the amount of 1 mL/kg. The blood sample in the volume of 2 mL was collected from the central artery of rabbit ears before injection and at 2, 6, 12, 24, 30, 36, 48, 60 hours post injection (PIH). Contents of TNF-α, IL-1, and IL-6 in the serum were determined with enzyme-linked immunosorbent assay. Data were processed with repeated measurement data analysis of variance and Spearman correlation analysis, and cubic model curve was applied in curve fitting for the contents of inflammatory factors.

RESULTS(1) The serum contents of TNF-α, IL-1, and IL-6 were increased in NTH, putrescine, and cadaverine groups in different degrees at most post injection time points. There was no significant change in the concentrations of the three pro-inflammatory factors in saline group, and they were significantly lower than those of the other three groups at most post injection time points (with F values from 3.49 to 13.58, P values all below 0.05). The serum contents of TNF-α, IL-1, and IL-6 in putrescine group began to increase at PIH 2, 6, and 6, which was similar to the trend of NTH group, but the changes were delayed compared with those of cadaverine group(all at PIH 2). The peak values of TNF-α, IL-1, and IL-6 in putrescine group were respectively (339 ± 36), (518 ± 44), and (265.9 ± 33.5) pg/mL, which were significantly lower than those of cadaverine group [ (476 ± 86), (539 ± 22), and (309.4 ± 27.1) pg/mL], with F values respectively 5.11, 1.90, and 5.56, P values all below 0.05. (2) The period of time in which contents of TNF-α, IL-1, and IL-6 began to increase (PIH 3-4) and the peaking time of the three pro-inflammatory cytokines (PIH 18-30) in putrescine group appeared later than those of cadaverine group (PIH 2 and 12-30). The duration of peaking time of the three pro-inflammatory cytokines in putrescine group was shorter than that of cadaverine group (PIH 18-30 vs. PIH 12-30). The increasing period and the duration of peaking time of TNF-α, IL-1, and IL-6 in putrescine group were close to those of NTH group (PIH 3-5 and 18-30). The correlation coefficient test analysis showed that the trends of changes in contents of three pro-inflammatory cytokines in putrescine group were significantly correlated with those of NTH group (r(TNF-α) = 0.933, P < 0.01; r(IL-1) = 0.967, P < 0.01; r(IL-6) = 0.950, P < 0.01). The obvious correlation between cadaverine group and NTH group was only found in the contents of IL-1 and IL-6 (r(IL-1) = 0.913, P < 0.01; r(IL-6) = 0.883, P < 0.05).

CONCLUSIONSBoth exogenous putrescine and cadaverine can cause inflammatory reaction in rabbits. The trend of the inflammatory reaction induced by putrescine was similar with that by NTH, suggesting that putrescine may play a leading role in the inflammatory reaction induced by necrotic tissue decomposition.