Is montelukast effective in regression of endometrial implants in an experimentally induced endometriosis model in rats?

OBJECTIVE Montelukast, a selective antagonist of Type 1 cysteinyl leukotriene receptors (CysLT1Rs), antagonizes the proinflammatory and proasthmatic activities of CysLT1Rs. We investigated the effect of montelukast on a surgically induced endometriosis rat model. STUDY DESIGN Thirty-two sexually mature, cycling, female Wistar-Albino rats, in which endometriotic implants were surgically induced, were randomly divided into three groups. Group I [Montelukast (M), 10 rats)] was given 1.6 mg/kg/day of oral montelukast sodium. Group II [Leuprolide acetate (L), 11 rats] was given 1 mg/kg single dose of s.c.leuprolide acetate. Group III [Control (C), 11 rats] received saline solution through an orogastric tube and served as controls. After a 3-weeks medication, the rats were sacrificed to investigate the endometriotic implants for size and morphological and histological characteristics, including immunoreactivity of MMP-2 and VEGF. RESULTS The mean area of implants decreased from 48.2 ± 24.7 to 29.3 ± 15.8mm(2) in Group I (M) (P = 0.008) and from 62 ± 32.1 to 39.9 ± 18.1mm(2) in Group II (L) (P=0.003). In Group III (C), the mean area increased from 41.1 ± 31.1 to 60.4 ± 37.1mm(2) (P = 0.025). Histopathological analysis showed statistically significant lower scores in rats treated with montelukast compared to leuprolide and controls. MMP H scores were not different between the groups in both epithelial and stromal MMP-2 immunostaining. VEGF H scores were statistically lower in Group 1 (M) in epithelial VEGF immunostaining when compared to Group II (L) and Group III (C) (P=0.006). CONCLUSION(S) Montelukast may effectively cause a significant decrease in the area of endometriotic implants.