Nitric oxide synthasis implication in indomethacin induced gastric mucosal lesion in albino rats: Immunohistochemical study

ABSTRACT

Eighty adult male albino rats weighing from 150-250 gm. were used in this study. They were divided into four groups Group I [control group] eight rats given distilled water 35 mg/kg subcutaneously. Group II [Indomethacin treated group] twenty-four rats received indomethacin subcutaneously as a single dose of 35-mg/kg body. Group III [Indomethacin and L-NAME treated rats] twenty-four rats received L-NAME [NG -nitro-L-arginine methyl ester] intraperitoneally at a dose of 50 mg/kg half an hour before giving the indomethacin intake. Group IV [Indomethacin and L-N treated rats] twenty-four rats were given L-NIL [N6-[iminoethyl]-L-lysin] intraperitoneally at a dose of 3 mg/k half an hour before giving the indomethacin injection. At the assigned time [after 6, 24 48 and 72 hours], the animals were sacrificed. The stomach was removed. The specimens were processed for paraffin sections at 4 microns and stained by immunohistochemical staining for eNOS and iNOS. Immunohistochemically stained sections were submitted for the image analysis to detect the optical densities of immunoreactivity of eNOS and iNOS in the specimens of studied groups. Immunohistochemically-stained sections with eNOS of the control group revealed the presence of immunoreactivity in the form of brown deposits of variable intensities in blood vessels of the lamina propria and in the deep half of the gastric glands. Immunohistochemically-stained sections with iNOS of the control group revealed immunoreactivity mainly in the cells of the lamina propria and in cells of gastric glands especially at the bases of the glands. Expression of iNOS was less prominent than with eNOS in normal gastric mucosa. In indomethacin-administration rats immunohistochemically-stained sections with eNOS revealed that the level of expression of eNOS was significantly increased after ulcer induction reaching its maximum level at 24 hours then, declined then, started to increase again on the 72 hours group. Immunohistochemically-stained sections with iNOS revealed that there was increase in the level of expression of iNOS reaching its maximum on the 72 hours group. Expression of both iNOS and eNOS was significantly high on the third day Statistical results revealed that expression of iNOS was more than eNOS. In indomethacin and LNAME treated rats, immunohistochemically-stained sections with eNOS revealed decrease in eNOS immunoreactivity from 6 hours until 72 hours reaching its minimum level on the third day. It was also observed that expression of eNOS was less than that in indomethacin only administration group on the 24 and 72 hours but higher than the control. Immunohistochemically-stained sections with iNOS revealed increase in iNOS immunoreactivity from 6 hours until 72 hours reaching its maximum level on the third day. Expression of iNOS was more than that in indomethacin given group or control group. It was observed that iNOS immunoreactivity was higher than eNOS immunoreactivity in this group. In indomethacin and L NIL treated rats, immunohistochemically-stained sections with eNOS revealed increase in eNOS immunoreactivity reaching its maximum level on 48 hours and 72 hours as compared with animals received indomethacin only or received indomethacin and L-NAME Immunohistochemically-stained sections with iNOS revealed decrease in iNOS immunoreactivity reaching its minimum level on the third day as compared with indomethacin and L-NAME given group but higher than the control group, also expression of iNOS was more in 6, 24, 48 hours groups but less in 72 hours group as compared with indomethacin only given group. The eNOS immunoreactivity was higher than iNOS immunoreactivity in this group. The present data suggested that eNOS-derived NO is the most important in terms of affects on the healing process, most likely through its effects on angiogenesis. It could be concluded that inhibition of NOS could have either beneficial or deleterious effects on gastric injury, depending on which isoforrn is being inhibited