It has been reported that the role of norepinephrine (NE) and dopamine (DA) in the brain is closely related to the etiology of attention-deficit/hyperactivity disorder (AD/HD). In this report, by using the HPLC method, the amounts of NE and DA in the locus ceruleus (LC), the medial prefrontal cortex (mPFC), and the striatum (Str) were measured and compared spontaneously hypertensive rats (SHR), an AD/HD model rat, and Wister-Kyoto rats (WKY) as the contrast rat. The results showed that the amount of NE were significantly larger than those in the mPFC and Str of WKY. On the other hand, the amount of DA has proven to be large in Str, and very small in the LC and the mPFC. This is also the case with SHR; the amount of NE and DA in LC, mPFC, and Str shows the same pattern. However, in the LC, the amount of NE in SHR was increased significantly more than that in WKY. The same tendency can be seen in mPFC, however, in Str, the amount of NE did not show any increase, compared with that in WKY. Furthermore, the amount of DA in the LC was increased significantly in SHR, compared with that in WKY, whereas any significant difference could not be recognized in mPFC and Str. These results suggest that the increase of NE and DA in the LC and mPFC of SHR is related to the characteristic behavior in AD/HD. [J Physiol Sci. 2006;56 Suppl:S173]
