title: Effects of nano and conventional zinc oxide on anxiety-like behavior in male rats.
abstract: OBJECTIVE
  Current drug therapies for psychological disorders, such as anxiety, are not as effective as expected, and it has been shown that zinc supplements, such as zinc oxide (ZnO), can influence anxiety. ZnO nanoparticles (ZnO NPs) are among the most used nanomaterials produced and applied in many products.
  
  
  METHODS
  This study investigated the effects of ZnO NPs in comparison with conventional ZnO (cZnO) on anxiety-like behaviors. Adult male Wistar rats were divided into groups: Control (receiving saline 0.9%), ZnO NPs (5, 10, 20 mg/kg), and cZnO (5, 10, 20 mg/kg). All drugs were dispersed in saline 0.9%, and 30 minutes after intraperitoneal (i.p.) injection of drugs, elevated plus maze apparatus was used to evaluate anxiety.
  
  
  RESULTS
  ZnO NPs (5 mg/kg) and cZnO (10 and 20 mg/kg) significantly increased the percentage of time spent in open arm (open arm time % OAT) compared with the control group (P < 0.05). This indicates the anxiolytic effect of such components; in addition, ZnO NPs (20 mg/kg) reduced locomotor activity (P < 0.05). Serum zinc concentration increased by both anxiolytic dose of components (from 1.75 ± 1.07 (mg/l) in control group to 5.31 ± 0.53 (mg/l) in ZnO NPs (5 mg/kg) and 10.38 ± 0.90 (mg/l) in cZnO (10 mg/kg) groups). Also, all doses increased serum pH (from 7.3 ± 0.05 in control group to 8.1 ± 0.05 in ZnO NPs (5 mg/kg) and 8.05 ± 0.01 in cZnO (10 mg/kg) groups and kept them constant after 24 hours.
  
  
  CONCLUSIONS
  Results indicate that the anxiolytic effect of ZnO NPs is much higher than its conventional form, but the introduction of ZnO NPs, as a new drug for treatment of anxiety disorder, needs further investigations.
authors.affiliation: Department of Biology, Shahid Chamran University, Ahvaz, Iran.
authors.forename: Mozhgan
authors.initials: M
authors.lastname: Torabi
authors.forename: Mahnaz
authors.initials: M
authors.lastname: Kesmati
authors.forename: Hooman Eshagh
authors.initials: HE
authors.lastname: Harooni
authors.forename: Hosein Najafzadeh
authors.initials: HN
authors.lastname: Varzi
mesh_terms: D000818:Animals; D001007:Anxiety / Q000188:drug therapy*; D001522:Behavior, Animal; D006863:Hydrogen-Ion Concentration; D008297:Male; D053768:Metal Nanoparticles; D051381:Rats; D017208:Rats, Wistar; D015032:Zinc / Q000097:blood; D015034:Zinc Oxide / Q000008:administration & dosage* / Q000627:therapeutic use*
chemical_list: D015032:Zinc; D015034:Zinc Oxide
keywords: Anxiety; Nano ZnO; plus maze; rat