title: Glycyrrhizin and long-term histopathologic changes in a murine model of asthma.
abstract: BACKGROUND
  Licorice root has been widely used to treat bronchial asthma for many years. However, the effect of this herb on lung histopathologic features is not fully understood.
  
  
  OBJECTIVE
  In this study, we aimed to determine the effects of oral administration of glycyrrhizin, an active constituent of licorice root, on lung histopathologic features in BALB/c mice, in which the model of chronic asthma was established.
  
  
  METHODS
  Twenty-eight BALB/c mice were divided into 4 groups: control, placebo, dexamethasone, and glycyrrhizin. Mice in the treatment and placebo groups were sensitized with 2 intraperitoneal injections of ovalbumin and then were exposed to aerosolized ovalbumin for 30 minutes per day on 3 days each week for 8 weeks beginning on the 21st study day. In the last week of inhalational exposure, mice in the placebo group received saline and those in the treatment groups received either dexamethasone, 1 mg/kg, or glycyrrhizin, 10 mg/kg, via orogastric gavage for 7 consecutive days. Animals were humanely killed 24 hours after the last ovalbumin and drug exposure. Lung histopathologic findings were evaluated using light and electron microscopy.
  
  
  RESULTS
  As evaluated in the control, placebo, dexamethasone, and glycyrrhizin groups, respectively, the mean (SD) basement membrane thickness was 306.34 (36.91), 657.52 (98.99), 405.13 (96.1), and 465.01 (121.48) nm; subepithelial smooth muscle thickness was 7.22 (1.37), 11.24 (1.85), 5.62 (1.15), and 7.76 (1.11) μm; epithelium thickness was 19.48 (1.22), 41.62 (5.49), 22.59 (3.18), and 25.54 (4.68) μm; number of mast cells was 1.34 (0.19), 3.62 (0.5), 2.06 (0.77), and 2.77 (0.23)/16,400 μm(2); and number of goblet cells was 0.32 (0.1), 4.92 (0.82), 0.66 (0.06), and 0.98 (0.15)/100 μm. Evaluation of lung histopathologic features demonstrated that the chronic asthma model of mice was successfully established, with significantly higher numbers of goblet and mast cells and increased thickness of epithelium, basement membrane, and subepithelial smooth muscle layers (P < 0.001 for all) in the asthma group compared with in the control group. The number of goblet (P < 0.001) and mast (P < 0.02) cells and the thickness of basement membrane (P < 0.001), subepithelial smooth muscle layers (P ≤ 0.001), and epithelium of the lung (P < 0.001) were found to be significantly lower in the glycyrrhizin group compared with in the placebo group. When the glycyrrhizin and dexamethasone groups were compared, there was no statistically significant difference between the 2 groups in the histopathologic parameters, including thickness of basement membrane (P = 0.514), subepithelial smooth muscle (P = 0.054), and epithelium (P = 1.0) and number of mast (P = 0.075) and goblet (P = 0.988) cells.
  
  
  CONCLUSIONS
  The results of this study suggest that the group receiving glycyrrhizin had amelioration of all established chronic histopathologic changes of lung in the mouse model of asthma. Further studies are needed to evaluate the efficacy of glycyrrhizin in the management of asthma.
authors.affiliation: Division of Allergy, Department of Pediatrics, Dokuz Eylul University Hospital, Izmir, Turkey.
authors.forename: Arzu Babayigit
authors.initials: AB
authors.lastname: Hocaoglu
authors.affiliation: Division of Allergy, Department of Pediatrics, Dokuz Eylul University Hospital, Izmir, Turkey.
authors.forename: Ozkan
authors.initials: O
authors.lastname: Karaman
authors.affiliation: Division of Allergy, Department of Pediatrics, Dokuz Eylul University Hospital, Izmir, Turkey.
authors.forename: Duygu Olmez
authors.initials: DO
authors.lastname: Erge
authors.affiliation: Department of Histology and Embryology, Dokuz Eylul University Hospital, Izmir, Turkey.
authors.forename: Guven
authors.initials: G
authors.lastname: Erbil
authors.affiliation: Department of Multidisciplinary Animal Laboratory, Dokuz Eylul University Hospital, Izmir, Turkey.
authors.forename: Osman
authors.initials: O
authors.lastname: Yilmaz
authors.affiliation: Department of Histology and Embryology, Dokuz Eylul University Hospital, Izmir, Turkey.
authors.forename: Alper
authors.initials: A
authors.lastname: Bagriyanik
authors.affiliation: Division of Allergy, Department of Pediatrics, Dokuz Eylul University Hospital, Izmir, Turkey.
authors.forename: Nevin
authors.initials: N
authors.lastname: Uzuner
keywords: BALB/c mice; Glycyrrhiza glabra; airway remodeling; asthma; glycyrrhizin; lung histopathology