Astrocytes release prostaglandin E2 to modify respiratory network activity

Abstract

Prostaglandin E2 (PGE2) released during hypercapnic challenge increases Ca2+ oscillation frequency in the chemosensitive parafacial respiratory group (pFRG/RTN). Here, we demonstrate that pFRG/RTN astrocytes are the PGE2 source. Two distinct astrocyte subtypes were found using transgenic mice expressing GFP and MrgA1 receptors in astrocytes. Although most astrocytes appeared dormant during time-lapse calcium imaging, a subgroup displayed persistent, rhythmic oscillating calcium activity. These active astrocytes formed a subnetwork within the respiratory network distinct from the neuronal network. Activation of exogenous MrgA1 receptors expressed in astrocytes tripled their calcium oscillation frequency activity in both the preBotzinger complex and pFRG/RTN. However, neurons in the preBotC were unaffected, whereas neuronal calcium oscillatory frequency in pFRG/RTN doubled. Notably, astrocyte activation in pFRG/RTN triggered local PGE2 release and blunted the hypercapnic response. Thus, astrocytes play an active role in respiratory rhythm modulation, modifying respiratory-related behaviorthrough PGE2 release in the pFRG/RTN.