Attenuated baroreflex control of sympathetic nerve activity in obese Zucker rats by central mechanisms

Domitila A. Huber and Ann M. Schreihofer May 1, 2010 The Journal of Physiology, 588, 1515-1525. doi: 10.1113/jphysiol.2009.186 In previous study they showed that obese zucker rats have impaired baroreflexes. This study was done in order to determine whether this impairment is due to altered afferent input to the CNS. They recorded aortic depressor nerve activity (ADNA) along with arterial pressure (AP) and splanchnic sympathetic nerve activity (sSNA) in obese and lean zucker rats. They basically recorded ADN responses along with AP and sSNA in response to phenylephrine. They looked at baseline sSNA but for the PE challenge they gave a ganglionic blocker to prevent any changes in SNA in response to AP changes. So they found that the change in AP and ADNA in both groups were similar. Suggesting that ADNA in response changes in systemic AP is not altered in obese zucker rats. However, in another set of experiments, when they stimulated the ADN and looked at AP and sSNA responses, they found that the obese zucker rats had attenuated sSNA and AP to different AND stimulation frequencies. However when changes in AP where clamped, they still saw attenuation in sSNA response in the obese zucker rat compared to the lean zucker rat. However there was no difference in AP between the two groups. These data suggest that the impairment of the baroreceptor reflex in obese zucker rats is due to altered signaling in the CNS pathway.-MD