title: Morphological evidence of an altered process of synaptic transcytosis in adult rats exposed to ethanol.
abstract: OBJECTIVE
  The effects of ethanol exposure on synaptic structure were investigated in the nucleus of solitary tract (NST) in rats, using the horse-radish peroxidase (HRP) method.
  
  
  METHODS
  Eight-week-old experimental rats were allowed free access to a liquid diet containing ethanol for 3 weeks, while controls were given an isocaloric diet. Some of the control and experimental animals were given an injection of wheat germ agglutinin conjugated with HRP (WGA-HRP) into the vagus nerve toward the end of the treatment period. After the treatment, the neuropil region of the NST was examined under an electron microscope.
  
  
  RESULTS
  We observed that a few terminals were characterized by deep indentation of axodendritic membranes into the post-synaptic neurons. This appeared to be similar to that commonly seen in exocrine glands. Interestingly, the indented portion often contained various sizes of vacuoles and flattened cisternae. HRP-reaction product (RP) transported to terminals was recognized easily as an electron-dense lysosomal substance when lead citrate staining was omitted. Terminals containing HRP-RP also revealed quite a similar structure with indentation of axodendritic membranes as described earlier. The results are considered to confirm that terminals forming 'apocrine-like structures' observed in the ethanol-fed animals with no injection of WGA-HRP originate from afferent fibers of the vagus nerve.
  
  
  CONCLUSIONS
  The present study suggests the possibility that the alteration of the synaptic structure induced by ethanol exposure can lead to the neuronal transcytosis of materials including proteins which is different from the normal vesicular exocytosis involved in chemical synaptic transmission.
authors.affiliation: Department of Anatomy and Neurobiology, Faculty of Medicine, Kagawa University, 1750-1 Ikenobe, Miki-cho, Kagawa 761-0793, Japan. takeuchi@med.kagawa-u.ac.jp
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Takeuchi
authors.forename: Takanori
authors.initials: T
authors.lastname: Miki
authors.forename: Jun-Qian
authors.initials: JQ
authors.lastname: Liu
authors.forename: Ken-Ichi
authors.initials: K
authors.lastname: Ohta
authors.forename: Katsuhiko
authors.initials: K
authors.lastname: Warita
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Matsumoto
authors.forename: Shingo
authors.initials: S
authors.lastname: Suzuki
authors.forename: Motoki
authors.initials: M
authors.lastname: Tamai
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Ameno
authors.forename: Kuldip Singh
authors.initials: KS
authors.lastname: Bedi
authors.forename: Tomiko
authors.initials: T
authors.lastname: Yakura
mesh_terms: D000818:Animals; D000431:Ethanol / Q000008:administration & dosage* / Q000633:toxicity; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D017552:Solitary Nucleus / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D013569:Synapses / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure*; D057900:Transcytosis / Q000187:drug effects* / Q000502:physiology
chemical_list: D000431:Ethanol