Regulation of the chemosensory control of breathing by Kölliker-Fuse neurons

Abstract

The Kölliker-Fuse region (KF) and the lateral parabrachial nucleus (LPBN) have been implicated in the maintenance of cardiorespiratory control. Here, we evaluated the involvement of the KF region and the LPBN in cardiorespiratory responses elicited by chemoreceptor activation in unanesthetized rats. Male Wistar rats (280-330 g; n = 5-9/group) with bilateral stainless-steel guide cannulas implanted in the KF region or the LPBN were used. Injection of muscimol (100 and 200 pmol/100 nl) in the KF region decreased resting ventilation (1,140 ± 68 and 978 ± 100 vs. saline: 1,436 ± 155 ml·kg(-1)·min(-1)), without changing mean arterial pressure (MAP) and heart rate (HR). Bilateral injection of the GABA-A antagonist bicuculline (1 nmol/100 nl) in the KF blocked the inhibitory effect on ventilation (1,418 ± 138 vs. muscimol: 978 ± 100 ml·kg(-1)·min(-1)) elicited by muscimol. Muscimol injection in the KF reduced the increase in ventilation produced by hypoxia (8% O2) (1,827 ± 61 vs. saline: 3,179 ± 325 ml·kg(-1)·min(-1)) or hypercapnia (7% CO2) (1,488 ± 277 vs. saline: 3,539 ± 374 ml·kg(-1)·min(-1)) in unanesthetized rats. Bilateral injection of bicuculline in the KF blocked the decrease in ventilation produced by muscimol in the KF during peripheral or central chemoreflex activation. Bilateral injection of muscimol in the LPBN did not change resting ventilation or the increase in ventilation elicited by hypoxia or hypercapnia. The results of the present study suggest that the KF region, but not the LPBN, has mechanisms to control ventilation in resting, hypoxic, or hypercapnic conditions in unanesthetized rats.

The First 5-Year-Long Survey on Intrauterine Unexplained Sudden Deaths from the Northeast Italy

“…After birth, the Kölliker-Fuse abruptly reduces its inhibitory effects and becomes active as a respiratory center able to coordinate the pulmonary motor responses to hematic oscillations of pO 2 , pCO 2 , and pH [23,24]. Also the arcuate nucleus contributes to this chemoreceptive activity in the modulation of the eupneic breathing [25].…”

Neural Control of Breathing and CO2 Homeostasis

“…RTN effects on inspiratory amplitude may derive from direct projections to inspiratory premotor neurons located in the rVRG (Figure 1J), the Kölliker-Fuse nucleus (not illustrated) (Bochorishvili et al, 2012; Damasceno et al, 2014; Mizusawa et al, 1995; Smith et al, 2013; Yokota et al, 2007) and the lateral parabrachial nucleus (Yokota et al, 2015). Control of expiration by the RTN (Abbott et al, 2011; Marina et al, 2010) may involve projections to bulbospinal expiratory premotor neurons located in the cVRG (Bochorishvili et al, 2012; Gerrits and Holstege, 1996) and to the nearby parafacial oscillator for active expiration (Figure 1K) (Feldman et al, 2013; Huckstepp et al, 2015).…”

Evolution and physiology of neural oxygen sensing

“…Other regions of the VRG, including the Bötzinger complex (BötC), the rostral ventral respiratory group (rVRG), and the caudal ventral respiratory group (cVRG), are also thought to be involved in the processing of the respiratory responses to chemoreflex activation, particularly in the forced inspiration and expiration pattern observed following carotid body activation (Guyenet, 2000; Abdala et al, 2009a; Mandel and Schreihofer, 2009; Zoccal et al, 2009b; Zoccal and Machado, 2011; Moraes et al, 2012b). The Retrotrapezoid nucleus (RTN) and the Parafacial Respiratory Group (RTN/pFRG), also receive chemoreflex related input (Figure 4) and are involved in the expiratory and sympatho-excitatory components of the response to hypoxia (Takakura et al, 2006; Abdala et al, 2009a; Abbott et al, 2011; Pagliardini et al, 2011; Takakura and Moreira, 2011; Damasceno et al, 2014a,b). In addition, there is growing evidence that NTS projections to pontine nuclei, especially to the parabrachial nucleus (PBN) and the Kölliker fuse (KF), also play an important role in the respiratory repercussions of chemoreflex activation (Abdala et al, 2009b; Costa-Silva et al, 2010; Song et al, 2011).…”