Glutamatergic receptor activation in the rostral ventrolateral medulla mediates the sympathoexcitatory response to hyperinsulinemia.

Hypertension. 2010 Feb;55(2):284-90. Bardgett ME, McCarthy JJ, Stocker SD. “Hyperinsulinemia increases sympathetic nerve activity (SNA) and has been linked to cardiovascular morbidity in obesity. The rostral ventrolateral medulla (RVLM) plays a key role in the regulation of SNA and arterial blood pressure (ABP)”. The authors tested the hypothesis whether glutamatergic receptor activation in the RVLM mediate sympathoexcitatory response to hyperinsulinemia. Microinjection of kynurenic acid, a glutamate receptor antagonist, into the RVLM significantly reduced lumbar sympathetic nerve activity during hyperinsulinemic euglycemic clamps in rats. On the other hand, insulin microinjection directly into the RVLM did not alter lumbar sympathetic nerve activity. Taken together these findings provided insight into the potential neural pathways and signaling mechanisms involved in insulin mediated increases in central sympathetic outflow and suggest that an excitatory glutamatergic pathway to the brainstem may be involved in insulin stimulated sympatho-excitation.- Madhan