title: Nicotine impact on the structure of adult male guinea pig auditory cortex.
abstract: BACKGROUND
  A growing body of evidence suggests that chronic cigarette smoking causes detrimental effects on brain morphology.
  
  
  OBJECTIVE
  To study the structural changes in auditory cortex region (Layer V), under the influence of nicotine.
  
  
  METHODS
  Three animal groups (10 each) were used; group I (control) and groups IIa and IIb received 3 and 6mg/kg nicotine respectively. The specimens from the auditory cortex were examined using light and electron microscopy and morphometry.
  
  
  RESULTS
  Neurons and blood capillaries of the auditory cortex (layer V), were influenced by chronic nicotine treatment in a dose dependent manner. The neurons and their processes revealed disorganization and dissociation of microtubules. The neuronal cells nucleoli characteristically revealed large fibrillar centers detected by silver stain and ultrastructure. The blood capillaries revealed collapse, irregular lumen, thickened basal lamina, abnormal forms of nuclei and organization of microtubules. Neuroglia revealed marked reactivity. Morphometrically, there was a significant decrease in the thickness of the auditory cortex and the number of light neurons and a significant increase in the number of dark neurons in comparison to the control.
  
  
  CONCLUSIONS
  Nicotine affects the integrity of the auditory cortex possibly by reducing metabolic and transcription activities.
authors.affiliation: Department of Histology, Faculty of Medicine, Assiut University, Assiut, Egypt. Electronic address: selgar1@hotmail.com.
authors.forename: Sanaa A M
authors.initials: SA
authors.lastname: Elgayar
authors.affiliation: Department of Histology, Faculty of Medicine, Assiut University, Assiut, Egypt.
authors.forename: Ola A
authors.initials: OA
authors.lastname: Hussein
authors.affiliation: Department of Histology, Faculty of Medicine, Assiut University, Assiut, Egypt.
authors.forename: Amel M M
authors.initials: AM
authors.lastname: Abdel-Hafez
authors.affiliation: Department of Histology, Faculty of Medicine, Assiut University, Assiut, Egypt.
authors.forename: Huda S A
authors.initials: HS
authors.lastname: Thabet
mesh_terms: D000818:Animals; D001303:Auditory Cortex / Q000187:drug effects* / Q000648:ultrastructure*; D002452:Cell Count; D006168:Guinea Pigs; D007279:Injections, Subcutaneous; D008297:Male; D046529:Microscopy, Electron, Transmission; D009474:Neurons / Q000187:drug effects* / Q000473:pathology / Q000648:ultrastructure; D009538:Nicotine / Q000008:administration & dosage / Q000633:toxicity*
chemical_list: D009538:Nicotine
keywords: Auditory cortex; Guinea pig; Nicotine; Ultrastructure