DBH and Parkinson disease: After DSP‐4 (or anti‐DBH‐saporin) injection, PD rats showed the lowest NE level (compared with 6‐OHDA group, p ≤ 0.05), and after yohimbine and guanfacine were applied to 6‐OHDA group, the contents of NE increased in the prefrontal cortex of rats.