Role of the hypothalamic arcuate nucleus in cardiovascular regulation

Hreday N. Sapru.Autonomic Neuroscience. Volume 175, Issues 1–2, April 2013, Pages 38–50.DOI: 10.1016/j.autneu.2012.10.016.  In ths review article the role of the arcuate nucleus was discussed.The arc is located in the hypothalamus and it has some projections that go to RVLM, NTS, CVLM, IML just to name some. The PVN receives the highest amount of projections from the arc when compared to the other regions mentioned above.  The arc extends to the median eminence, which is area that lacks a BBB. This allows for the arc to be exposed to leptin, glucose and angiotensin.  What I found most interesting was that stimulation of the arc can cause both depressor and pressor responses. When blood pressor is normal activation of the arc leads to depressor responses ( release of GABA, neuropeptide y, and beta endorphin) most likely due to inactivation of neurons in the PVN that project down to the spinal cord or RVLM and lead to decreased sympathetic activity. However when blood pressure is low, activation of neurons in the arc leads to pressor responses (most likely due to the release of glutamate). The baroreceptor reflex may play also play role in how blood pressure is modulated in response to activation of the arc neurons. It has been shown that following barodenervation, stimulation of the arc leads to pressor responses. This may suggest that the baroreceptors are important for providing inhibitory input on to glutamate releasing arc neurons. overall I thought that this could be a region that we investigate in the future since it could be

 playing a role in both  activation and inhibition of the rvlm neurons. -MD