The cholinergic stimulation of the hippocampus induced the activation of the sympathetic nervous system.

OBJECTIVES: We previously demonstrated that the direct microinjection of cholinesterase inhibitor (neostigmine) into the hippocampus in rats activated the hypothalamo-pituitary -adrenal axis and increased the level of norepinephrine in the plasma. In the current study we tried to measure the effects of neostigmine injection into the hippocampus using the non-invasive measure of heart rate variability (HRV).

MATERIALS AND METHODS: After the hippocampal injection of neostigmine (50 nM and 125 nM) or saline as a control in rats, HRV measurement was performed for 30 min.

RESULTS: After the injection of neostigmine into the hippocampus, LF/HF, the index of the sympathetic nervous system, significantly increased.

CONCLUSIONS: The results of the current study indicated that stimulation of the hippocampal cholinergic system induced the activation of the sympathetic nervous system.