抄録
Dysfunction of noradrenaline (NA) system in the brain is known to be closely related to the etiology of attention-deficit hyperactivity disorder (AD/HD). To determine whether the release of NA in the locus coeruleus (LC), the main source of NA in the brain, is also enhanced in the SHR compared to WKY, the NA content in the homogenate LC tissue and the extracellular levels of NA in the LC were quantified in the present study. The NA content in the homogenate LC tissue obtained from rats strictly at the period of juvenile (5 week-old), was measured by HPLC. Next, the extracellular levels of NA in the LC were measured at the period of juvenile (5 week-old) and adolescent (WKY: 12 week-old, SHR: 14 week-old), by using in vivo microdialysis, following the determination of the location of the LC. The results showed that the NA content in the homogenate tissue of the LC was significantly higher in SHR than that of WKY in juvenile animals, however, the significant difference was not detected in the extracellular levels of NA in the LC between SHR and WKY in both juvenile and adolescent animals. In conclusion, the present results indicate that the rate of NA synthesis in the LC is increased in SHR compared to that in WKY, whereas both release and reuptake of NA similarly function in these two strains or these functions are accelerated in SHR compared to WKY. [J Physiol Sci. 2008;58 Suppl:S124]
