INSR and hyperinsulinism: Although, the PVN and RVLM are believed to be involved in mediating the sympatho-excitatory effects of hyperinsulinemia, microinjections of insulin directly into those brain nuclei did not induce an increased sympathetic nerve activity suggesting there is no direct activation of insulin receptors in those brain nuclei (Bardgett et al., 2010; Ward et al., 2011; Stocker and Gordon, 2015).