Abstract
Aim:
To test the effect of orexin-A (hypocretin-1), a neuropeptide synthesized in the lateral hypothalamus and the perifornical area, on the glycinergic inputs and the GABAergic inputs of cardiac vagal neurons (CVN).
Methods:
The effects of orexin-A at three concentrations (20 nmol/L, 100 nmol/L, 500 nmol/L) on the glycinergic inputs and the GABAergic inputs were investigated by using retrograde fluorescent labeling of cardiac neurons (CVN) in the nucleus ambiguus (NA) and the voltage patch-clamp technique.
Results:
Orexin-A dose-dependently increased the frequency of both the glycinergic and the GABAergic spontaneous inhibitory postsynaptic currents (sIPSC). However, at a lower concentration (20 nmol/L) of orexin-A, although the frequency of the glycinergic sIPSC was significantly increased, the frequency of the GABAergic sIPSC was not significantly changed.
Conclusion:
The glycinergic inputs and the GABAergic inputs have different sensitivities to orexin-A, which suggests that the two kinds of inhibitory inputs might play different roles in the synaptic control of cardiac vagal functions.
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Project supported by grants from Shanghai Education and Development Foundation (03SG06) and National Natural Science Foundation of China (No 30470690).
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Wang, Jj., Chen, Yh., Li, Ky. et al. Differential sensitivity of GABAergic and glycinergic inputs to orexin-A in preganglionic cardiac vagal neurons of newborn rats. Acta Pharmacol Sin 26, 1442–1447 (2005). https://doi.org/10.1111/j.1745-7254.2005.00231.x
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DOI: https://doi.org/10.1111/j.1745-7254.2005.00231.x