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

Full cite: Huber DA & Schreihofer AM (2010). Attenuated baroreflex control of sympathetic nerve activity in obese Zucker rats by central mechanisms. J Physiol 588, 1515–1525.

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

Domitila A. Huber and Ann M. Schreihofer

Department of Physiology, Medical College of Georgia, Augusta, GA, USA

This study is looking at how reflex control of the vasculature is affected by obesity; the main technique they are using in this paper is electrophysiology. It is widely known that obesity is a risk factor for the development of hypertension, in addition to this; obesity has been shown to be an independent contributor to the elevation of sympathetic nerve activity (SNA). The goal of this paper is to illuminate how obesity alters sympathoregulation, in an attempt to tie the condition to other disease states. The main component of sympathetic control examined is the sympathetic baroreflex responses, with an attempt to see if it is altered due to altered sensory or central mechanisms. It has been a long while since I’ve read a Zucker rat paper, adult obese Zucker rats (OZRs) vs. lean Zucker rats (LZRs) were the rats used in this study. The OZRs weighed about 600g and the LZRs weighed about 400g on average. The OZRs had significantly higher resting sympathetic nerve activities and blood press, interestingly enough they did not have significantly different heart rate. Stimulation of the aortic depressor nerve (ADN) elicited blunted responses in the OZRs, whereas the net responses in the LZRs were significantly greater. This result suggests that OZRs are less sensitive to stimulation of the ADN. In addition, stimulation of the vagal afferent nerve brought about significantly greater responses in the LZR when compared to the OZR. These results suggest that the vagal afferents have inherently less sensitive in the OZR rats. This reduction in baroreflex sensitivity in the OZRs may contribute to the likelihood of cardiovascular diseases in overweight individuals. -MTL