role of Nitric Oxide synthases inhibitors in indomethacin induced gastric mucosal lesion in albino rat

ABSTRACT

The present work was undertaken to explore the role of nitric oxide synthases [NOSs] inhibitors L-NAME [non-selective constitutive NOS and inducible NOS inhibitor] and L-NIL [selective inducible NOS inhibitor] in the pathogenesis of indomethacin induced gastric mucosal lesions in the early stage of ulcer development and healing [0-3 days]. 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 initro-L-arginine methyl ester] intraperitoneally at a dose of 50 mg/kg half an hour before giving the indomethacin Group IV [Indomethacin and L-NIL treated rats] twenty-four rats were given L-NIL [N6- [iminoethyl]-L-lysine] intraperitoneally at a dose of 3 mg/kg half an hour before giving the indomethacin. At the assigned time [after 6 hours, 24 hours, 48 hours and 72 hours] the animals were sacrificed. The stomach was removed and dissected along the greater curvature. The macroscopic lesions in obtained specimens were assessed by magnifying lens and dissecting microscope The numerical data obtained from macroscopic studies of stomach sections were statistically analyzed to obtain the mean ulcer index. The specimens were processed for paraffin sections at 6 microns and stained by haematoxylin and eosin stain; and examined histologically. In the control group, macroscopic and histological examination revealed normal appearance of the gastric mucosa. In indomethacin-administrated group, macroscopic and histological examination revealed time-dependent occurrence of damage in the stomach from 6 hours up to 72 hours reaching maximum damage at 72 hours. After 72 hours, there was evidence of healing process. In indomethacin and L-NAME administrated group, it was observed that pre-treatment with L-NAME significantly enhanced gastric mucosal lesions induced by indomethacin. Macroscopic and histologieal examination revealed significant increase in the mean ulcer index in the mucosa of the stomach as compared with indomethacin only given rats reaching its maximum effect on the third day. No or little evidence of regenerating epithelium on the third day was observed. In indomethacin and L-NIL administrated group, it was observed that pre-treatment with L-NIL significantly reduced but not prevented gastric mucosal lesions induced by indomethacin. Macroscopic and histological examination revealed time-dependent occurrence of damage in the stomach from 6 hours up to 48 hours reaching maximum damage at 48 hours then ulcer index began to decrease on 72 hours. There was decrease in the mean ulcer index as compared with rats given either indomethacin and L-NAME or indomethacin only. Evidence of healing was observed in 48 hours and 72 hours groups. The results of the present study confirmed the importance of NOS inhibitors in the modulation of gastric ulcer healing in early stage of ulcer development [0-3] days. The present data suggested that eNOS-derived NO is the most important in terms of effects on the healing process, most likely through its effects on angiogenesis