高原地区烧伤后延迟复苏氧化应激对大鼠肠上皮细胞凋亡及bax和bcl-2基因表达的影响

Objective To explore influence of oxidative stress reaction on apoptosis rate and expres-sion of apoptosis-related genes bax and bcl-2 of enterocytes in severely burned rats with delayed resuscitation on the plateau. Methods One hundred and twenty rats subjected to 30% TBSA full-thickness scald on the back were derided into plateau experimental group (PE, altitude 3840 m) and Lanzhou experimental group (LE, altitude 1517 m). Then LE and PE groups were subdivided into Lanzhou immediate fluid resus-citation group (LIFR, with immediate intraperitoneal injection of isotonic saline after scald, 40 mL/kg), Lanzhou delayed fluid resuscitation group [LDFR, with intraperitoneal injection of isotonic saline at 6 post scald hour (PSH), 40 mL/kg], and plateau immediate fluid resuscitation group (PIFR, with immediate in-traperitoneal injection of isotonic saline after scald, 40 mL/kg), plateau delayed fluid resuscitation group (PDFR, with intraperitoneal injection of isotonic saline at 6 PSH, 40 mL/kg). Another 12 rats were divided into Lanzhou sham scald group (LS) and plateau sham scald group (PS), with 6 rats in each group. Rats in LS and PS groups were sham scalded in a water bath for 15 s without fluid infusion. Rats were sacrificed at 6, 12, 24, 48, 72 PSH for collection of small intestine samples to determine the contents of malonaldehyde (MDA) and total hydrosulfide (TSH). The apoptosis of enterocytes was determined by TUNEL, and the ex-pression of bax and bcl-2 in epithelial cells were observed by immunohistochemical method. Intestinal sample of LS and PS groups were collected to determine the contents of MDA and TSH. Results After being scal-ded, content of MDA in intestinal tissue of rats in LDFR group and PDFR group was respectively greater than that in LIFR group and PIFR group (P<0.05 or P<0.01). Intestinal tissue content of MDA of rats in LDFR group (9.8±4.0 nmol/mg) and PDFR group (10.2±1.3 nmol/mg) was respectively greater than that in LIFR group (9.5±2.7 nmol/mg) and PIFR group (9.6±1.1 nmol/mg) (P<0.05) at 24 PSH. After being scalded, intestinal content of TSH of rats in PE group and PDFR group was respectively smaller than that in LE group and LIFR group (P<0.05). A multitude of brown positive apoptotic cells were ob-served in PDFR at 6 and 12 PSH. Absorbance values in LDFR group, PIFR group, and PDFR group were higher than that in LIFR group at each time point (P<0.05 or P<0.01). A multitude of bax positive cells were observed in intestinal mucous membrane in PDFR at 6 and 12 PSH. Expression of bal-2 was nega-tive in PE group, and LIFR and LDFR groups at 6, 12 PSH, and it was weakly positive in LIFR and LDFR groups at 24, 48, 72 PSH. Conclusions Enhancement of bax expression and weakening of bcl-2 expres-sion in enterocytes are induced by the severe oxidative stress reaction in intestinal mucous membrane after burn with delayed resuscitation on the plateau, which may be one of the important reasons in inducing an in-crease in apoptosis of enterocytes.

Influence of oxidative stress on apoptosis and expression of bax and bcl-2 of enterocytes in burn rats with delayed resuscitation on the plateau

Objective To explore influence of oxidative stress reaction on apoptosis rate and expres-sion of apoptosis-related genes bax and bcl-2 of enterocytes in severely burned rats with delayed resuscitation on the plateau. Methods One hundred and twenty rats subjected to 30% TBSA full-thickness scald on the back were derided into plateau experimental group (PE, altitude 3840 m) and Lanzhou experimental group (LE, altitude 1517 m). Then LE and PE groups were subdivided into Lanzhou immediate fluid resus-citation group (LIFR, with immediate intraperitoneal injection of isotonic saline after scald, 40 mL/kg), Lanzhou delayed fluid resuscitation group [LDFR, with intraperitoneal injection of isotonic saline at 6 post scald hour (PSH), 40 mL/kg], and plateau immediate fluid resuscitation group (PIFR, with immediate in-traperitoneal injection of isotonic saline after scald, 40 mL/kg), plateau delayed fluid resuscitation group (PDFR, with intraperitoneal injection of isotonic saline at 6 PSH, 40 mL/kg). Another 12 rats were divided into Lanzhou sham scald group (LS) and plateau sham scald group (PS), with 6 rats in each group. Rats in LS and PS groups were sham scalded in a water bath for 15 s without fluid infusion. Rats were sacrificed at 6, 12, 24, 48, 72 PSH for collection of small intestine samples to determine the contents of malonaldehyde (MDA) and total hydrosulfide (TSH). The apoptosis of enterocytes was determined by TUNEL, and the ex-pression of bax and bcl-2 in epithelial cells were observed by immunohistochemical method. Intestinal sample of LS and PS groups were collected to determine the contents of MDA and TSH. Results After being scal-ded, content of MDA in intestinal tissue of rats in LDFR group and PDFR group was respectively greater than that in LIFR group and PIFR group (P<0.05 or P<0.01). Intestinal tissue content of MDA of rats in LDFR group (9.8±4.0 nmol/mg) and PDFR group (10.2±1.3 nmol/mg) was respectively greater than that in LIFR group (9.5±2.7 nmol/mg) and PIFR group (9.6±1.1 nmol/mg) (P<0.05) at 24 PSH. After being scalded, intestinal content of TSH of rats in PE group and PDFR group was respectively smaller than that in LE group and LIFR group (P<0.05). A multitude of brown positive apoptotic cells were ob-served in PDFR at 6 and 12 PSH. Absorbance values in LDFR group, PIFR group, and PDFR group were higher than that in LIFR group at each time point (P<0.05 or P<0.01). A multitude of bax positive cells were observed in intestinal mucous membrane in PDFR at 6 and 12 PSH. Expression of bal-2 was nega-tive in PE group, and LIFR and LDFR groups at 6, 12 PSH, and it was weakly positive in LIFR and LDFR groups at 24, 48, 72 PSH. Conclusions Enhancement of bax expression and weakening of bcl-2 expres-sion in enterocytes are induced by the severe oxidative stress reaction in intestinal mucous membrane after burn with delayed resuscitation on the plateau, which may be one of the important reasons in inducing an in-crease in apoptosis of enterocytes.