Hindbrain Astrocyte Glucodetectors and Counterregulation

Excerpt

Astrocytes have classically been associated with maintenance of neurons. However, since the late 1990s, there has been a dramatic shift in the recognition of the role of astrocytes in central nervous system (CNS) function from passive supporter to active participant (Araque et al. 1999, Bushong et al. 2002, Halassa et al. 2007, Halassa and Haydon 2010, Perea, Navarrete, and Araque 2009, Vance, Rogers, and Hermann 2015). The degree to which astrocytes are involved in regulating central nervous system-wide synaptic function is controversial (Agulhon, Fiacco, and McCarthy 2010, Smith 2010). However, the hindbrain astrocyte has emerged as a powerful component in homeostatic regulation (Agulhon et al. 2013, Funk 2010, Gourine and Kasparov 2011, Gourine et al. 2010, Hermann et al. 2009, Lin et al. 2013, McDougal, Hermann, and Rogers 2013, Vance, Rogers, and Hermann 2015). There are several reports of astrocyte involvement in the regulation of hindbrain synaptic activity (Accorsi-Mendonca, Bonagamba, and Machado 2012, Vance, Rogers, and Hermann 2015), neural inputs regulating astrocyte function (McDougal, Hermann, and Rogers 2011, Porter and McCarthy 1996), and astrocyte involvement as detectors of physiological parameters critical to the maintenance of homeostasis (Funk 2010, Gourine and Kasparov 2011, Accorsi-Mendonca, Bonagamba, and Machado 2012). This chapter reviews recent data that support a special function of astrocytes in the detection of hypoglycemic emergencies and initiation of the rapid, life-saving homeostatic adjustments to hypoglycemia together referred to as “counterregulation.”