Abstract
Arterial pressure (AP) shows circadian variation and changes with vigilance state (sleep/wake). AP and heart rate (HR) decrease during resting period (light phase for rats or mice) in comparison to active period (dark phase). During non-REM sleep, autonomic functions such as AP, HR and respiration are quite stable showing constant values throughout this stage. However, during REM sleep, significant fluctuations in autonomic functions can be observed. AP increases in the transition from non-REM to REM sleep, exhibiting large phasic surges during REM sleep, although the skeletal muscles lose their activity completely. Injection of 6-hydroxydopamine (6-OHDA), which is one of cathecholaminergic neurotoxin, into the ventral tegmental are (VTA) induces the destruction of dopaminergic midbrain-nucleus accumbens (NAc) pathway. We have observed that 6-OHDA injection into VTA causes the attenuation of both circadian variation and fluctuation during REM sleep in AP. Non-dipping type of AP circadian rhythm and a variety of sleep disorders are characteristics of Parkinson's disease. We now therefore hypothesize that the midbrain dopaminergic system, especially midbrain-NAc pathway, may have the important role on the circadian and sleep-related control of AP. [Jpn J Physiol 54 Suppl:S25 (2004)]
