Cholecystokinin selectively affects presympathetic vasomotor neurons and sympathetic vasomotor outflow

Daniela M. Sartor , Anthony J. M. Verberne Am J Physiol Regul Integr Comp Physiol. 2002 Apr;282(4):R1174-84. “CHOLECYSTOKININ(CCK) is a gastrointestinal hormone with actions including gastrointestinal vasodilatation reduced gut motility, gastric acid secretion, and pancreatic secretion”. CCK is an abundant neuropeptide with a central role in satiety. Its receptors are located on the vagal afferents and NTS. The authors were interested to study the effects of CCK on sympathetic vasomotor outflow on spinally projecting neurons of the RVLM. CCK was given intravenously and parameters such as mean arterial pressure, heart rate, lumbar sympathetic nerve discharge, splanchnic sympathetic nerve discharge were recorded. The authors investigated the effect of CCK on the discharge of presympathetic neurons of the RVLM to determine whether CCK could discriminate subgroups of these neurons. Also the importance of vagal afferents and involvement of specific CCK receptor subtype were examined. CCK produced differential effects on sympathetic vasomotor outflow, a dose dependent activation of LSND and inhibition of SSND. The differential effect of CCK on RVLM presympathetic neurons includes inhibition in some cells, activation in some and no changes in others. These findings suggest that vagal afferents are heterogeneous, meaning some of its population produces an inhibitory effect, some excitatory effect on sympathetic vasomotor function. In addition to these findings, the authors demonstrate that the effects of CCK are mediated by activation of CCK-A receptors. -Madhan