Muscarinic acetylcholine receptor in cerebellar cortex participates in acetylcholine-mediated blood depressor response in rats

Our previous investigations have revealed that cerebellar cholinergic innervation is involved in cardiovascular regulation. This study was performed to examine the effects of the muscarinic cholinergic receptor (mAChR) in the cerebellar cortex on blood pressure (BP) modulation in rats. Acetylcholine (ACh, 100 mM), nonselective mAChR agonist (oxotremorine M; Oxo-M, 10, 30 and 100 mM) and 100 mM ACh mixed with nonselective mAChR antagonist atropine (1, 3 and 10 mM) were microinjected into the cerebellar cortex of anesthetized rats. Mean arterial pressure (MAP), maximal decreased MAP (MDMAP), and reaction time (duration required for BP to return to basal values) were measured and analyzed. The results showed that Oxo-M dose-dependently decreased MAP, increased MDMAP, and prolonged reaction time, which displayed a homodromous effect of ACh-mediated blood depressor response; meanwhile, atropine concentration-dependently blocked the effect of ACh on the BP regulation. In conclusion, the present study showed for the first time that mAChRs in cerebellar cortex could modulate somatic BP by participation in ACh-mediated depressor response.