title: The effect of gamma knife irradiation on functions of striatum in rats.
abstract: OBJECTIVE
  An animal model has been developed to study the effect of gamma knife surgery(GKS) on cerebral function.
  
  
  METHODS
  A rat was fixed in a newly developed Régis-Valliccioni frame that enables the target region to be planned directly on the magnetic resonance images. The left striatum was irradiated with 150 Gy via a 4-mm collimator of the Leksell gamma knife. Apomorphine (dopamine agonist) was administered to elicit a circling behavior (apomorphine test) after the GKS so as to examine the time course of the changes in dopaminergic functions of irradiated striatum. After a series of behavioral analyses, irradiated brains were subjected to histological examination. Necrosis was observed in the irradiated area surrounded by hemorrhage and gliosis. The distance between the histologically estimated and planned centers of the irradiation areas was 1.0 +/- 0.5 mm. The extent of the distance was due to errors along dorsoventral axis. The distribution of the irradiation areas influenced the activity and the circling behaviors in apomorphine test, which was suggestive of involvement of the nigrostriatal pathway.
  
  
  CONCLUSIONS
  Targeting by using the Régis-Valliccioni frame was very accurate compared with targeting with coordinates based on brain maps used hitherto. Although targeting improved the accuracy, further effort will still be necessary to reduce errors along dorsoventral axis. The apomorphine test indicated a reduced dopaminergic function of the irradiated area including striatum, which accompanied histological changes after a high dose of irradiation (150 Gy).
authors.affiliation: Department of Physiology and Neurosurgery, School of Medicine, Tokyo Women's Medical University, Shinjuku City, Tokyo, Japan. ostokuma@research.twmu.ac.jp
authors.forename: Osamu
authors.initials: O
authors.lastname: Tokumaru
authors.forename: Mihoko
authors.initials: M
authors.lastname: Tomida
authors.forename: Yoko
authors.initials: Y
authors.lastname: Katayama
authors.forename: Mootohiro
authors.initials: M
authors.lastname: Hayashi
authors.forename: Yoriko
authors.initials: Y
authors.lastname: Kawakami
authors.forename: Nobuo
authors.initials: N
authors.lastname: Kouyama
mesh_terms: D000818:Animals; D001058:Apomorphine / Q000008:administration & dosage / Q000494:pharmacology; D002543:Cerebral Hemorrhage / Q000209:etiology; D003342:Corpus Striatum / Q000187:drug effects / Q000473:pathology / Q000601:surgery*; D018491:Dopamine Agonists / Q000008:administration & dosage / Q000494:pharmacology; D004867:Equipment Design; D005911:Gliosis / Q000209:etiology; D008279:Magnetic Resonance Imaging; D008297:Male; D009336:Necrosis / Q000473:pathology; D011183:Postoperative Complications; D011829:Radiation Dosage; D016634:Radiosurgery / Q000295:instrumentation*; D051381:Rats; D017208:Rats, Wistar; D013378:Substantia Nigra / Q000187:drug effects / Q000473:pathology / Q000601:surgery
chemical_list: D018491:Dopamine Agonists; D001058:Apomorphine