OBJECTIVETo explore the influence of exogenous putrescine on the function of liver and apoptosis of liver cells in rats.

METHODSNinety healthy clean SD rats were divided into control group (C, n = 10, intraperitoneally injected with 2 mL normal saline), low dosage putrescine group (LP, n = 40), and high dosage putrescine group (HP, n = 40) according to the random number table. Rats in the latter two groups were intraperitoneally injected with approximately 2 mL putrescine (2.5 or 5.0 g/L) with the dosage of 25 or 50 µg/g. Ten rats from group C at post injection hour (PIH) 24 and 10 rats from each of the latter two groups at PIH 24, 48, 72, 96 were sacrificed. Heart blood was obtained for determination of serum contents of ALT and AST. Liver was harvested for gross observation and histomorphological observation with HE staining. Apoptosis was shown with in situ end labeling, and apoptosis index (AI) was calculated. Data among the three groups and those at different time points within one group were processed with one-way analysis of variance or Welch test; LSD or Dunnett's T3 test was used for paired comparison; factorial design analysis of variance of two factors was applied for data between group LP and group HP.

RESULTS(1) No obvious abnormality was observed at gross observation of liver of rats in each group. Liver tissue of rats in group C was normal. Light edema was observed occasionally in liver of rats in groups LP and HP, but necrotic cells were not seen. (2) Content of ALT at PIH 24, 48, 96 and content of AST at PIH 72 and 96 in group LP were respectively (38 ± 10), (45 ± 6), (34 ± 4), (207 ± 18), (196 ± 19) U/L, and content of ALT at PIH 72 and 96 and content of AST at PIH 24, 72, 96 in group HP were respectively (38 ± 6), (48 ± 5), (213 ± 43), (209 ± 40), (230 ± 29) U/L. They were significantly higher than those of rats in group C [(29 ± 5), (163 ± 42) U/L, with P values all below 0.01]. There were statistically significant differences between group LP and group HP in the content of ALT at PIH 48, 72, 96 and content of AST at PIH 96 (with P values all below 0.05). Compared with that at PIH 24 of each group, content of ALT of rats in group LP at PIH 48 and that of rats in group HP at PIH 96, as well as content of AST of rats in group LP at PIH 48, 72, 96 and that of rats in group HP at PIH 48 were significantly increased or decreased (with P values all below 0.05). Factorial analysis showed that the differences due to different concentration of putrescine on content of AST were statistically significant (F = 12.21, P = 0.001), but not on content of ALT (F = 0.01, P = 0.974) between group LP and group HP. (3) AI values of rats in group LP at PIH 24, 48, 72 were respectively (5.69 ± 0.38)%, (13.80 ± 1.66)%, (11.56 ± 1.74)%, and AI values of rats in group HP at PIH 72 and 96 were respectively (10.29 ± 1.43)%, (15.29 ± 1.41)%. They were all obviously higher than AI value of control group at PIH 24 [(3.50 ± 0.30)%, with P values all below 0.01]. There were statistically significant differences between group LP and group HP in AI value at PIH 24, 48, 96 (with P values all below 0.05). Compared with that at PIH 24 of each group, AI value of rats in groups LP and HP at PIH 48, 72, 96 were significantly increased or decreased (with P values all below 0.05). Factorial analysis showed that the differences in the influence of concentration of putrescine and stimulation time on AI value were statistically significant (with F values respectively 22.95 and 130.44, P values all below 0.01).

CONCLUSIONSIntraperitoneal injection of exogenous putrescine in the dosage of 25 or 50 µg/g could lead to certain degree of functional damage of liver and apoptosis of liver cells of rat. The higher the dosage and the longer the stimulation time, the more obvious the damage and apoptosis would be.