Experimental study on the effects of organic solvent exposure to development of GABAergic system in juvenile rats

2004 Fiscal Year Final Research Report Summary

• Project/Area Number: 15590512
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Hygiene
• Research Institution: OKAYAMA UNIVERSITY
• Principal Investigator: ITO Takehiko Okayama University, Faculty of Education, Associate Professor, 教育学部, 助教授 (10291973)
• Project Period (FY): 2003 – 2004
• Keywords: organic solvent intoxication / m-xylene / GABAergic system / immunohistochemistry / exposure system / juvenile animals / autoradiography / inhalation study

Research Abstract

1.Development of an exposure system suitable for exposing vapor of organic solvents to juvenile animals (rats) and inhalation study using the system
An exposure system suitable for exposing vapor of organic solvents to juvenile animals was developed.
The inner environment of the exposure chamber was designed for young rats. An ordinary mice cage with gas inlets and outlets was completely wrapped with a special gas-tight plastic bag, which was then used as the exposure chamber. With this system, inhalation study in three-week old rats was conducted. The protocol of the exposure was as follows : m-xylene at 250 ppm, 6 h/day for 14 consecutive days.
2.Behavioral study
Rotarod test was employed to see the effect of m-xylene of the development of the CNS. Generally co-ordination of the motor system is assessed with this test. Exposed rats showed better coordination than controls, and further study is warranted to explain the unexpected results.
3.Histological study
Brain sections were made after the series of exposures. The section was stained using Luxol Fast Blue and Cresyl Violet double stain, to see possible lesions involving myelin. No significant change was observed. Immunohistochemical studies using anti-glutamate decarboxylase antibody and anti-GABA_A receptor alpha 6 subunit antibody were done, but no significant change was pointed out.
Receptor binding autoradiography using [^3H]Ro15-4513 was performed. The distribution of the binding was identical to that of signals in immunostain of GABA_A receptor alpha 6 subunit. No significant change was observed.
The present results suggested that there may be some significant change in locomotor function with this exposure protocol. A study in catecholaminergic and/or serotonergic system should be included along with that in GABAergic systems in the future studies.