Neurokininergic Mechanism within the Lateral Crescent Nucleus of the Parabrachial Complex Participates in the Heart-Rate Response to Nociception

Abstract

We wanted to ascertain whether the lateral parabrachial nucleus was involved in mediating the heart-rate response evoked during stimulation of somatic nociceptors. Reversible inactivation of the lateral parabrachial nucleus, using a GABA A agonist, reduced the reflex tachycardia evoked during noxious (mechanical) stimulation of the forelimb by ϳ50%. The same effect was observed after blockade of neurokinin 1 receptors within the lateral parabrachial nucleus, indicating a possible involvement for substance P as a neurotransmitter. Immunocytochemistry revealed a strong expression of substance P-immunoreactive fibers and boutons in all lateral subnuclei, but they were particularly dense in the lateral crescent subnucleus. Histological verification showed that the most effective injection sites for attenuating the noxious-evoked tachycardia were all placed in or near to the lateral crescent nucleus of the lateral parabrachial complex. Many single units recorded from this region were activated by high-intensity brachial nerve stimulation. The brachial nerve evoked firing responses of some of these neurons was reversibly reduced after local delivery of a neurokinin 1 receptor antagonist. However, only a minority of these neurons followed a paired-pulse stimulation protocol applied to the spinal cord, suggesting a predominance of indirect projections from the spinal cord to the parabrachial nucleus. We conclude that the cardiac component of the response to somatic nociception involves indirect spinal pathways that most likely excite neurons located in the lateral crescent nucleus of the parabrachial complex via activation of neurokinin 1 receptors.

Cytoarchitecture of Pneumotaxic Integration of Respiratory and Nonrespiratory Information in the Rat

“…Recently, it was reported that certain respiratory rhythmic neurons in KF responded to cutaneous noxious stimuli and that the resulting respiratory enhancement was attenuated by bilateral inhibition of the parabrachial complex (Jiang et al, 2004). In addition, neurons in the lateral parabrachial nucleus were found to mediate the nociceptic cardiac response (Boscan et al, 2005). These physiologic observations combined with the present anatomic evidence strongly suggest that pneumotaxic neurons are capable of integrating nociceptive and respiratory-related information to coordinate respiratory movement with defensive somatic response.…”

Comparison of somatostatin and corticotrophin-releasing hormone immunoreactivity in forebrain neurons projecting to taste-responsive and non-responsive regions of the parabrachial nucleus in rat

“…One interpretation is that forebrain induced pressor and respiratory responses are mediated by descending projections to rostral PBN. This notion gains support from experiments showing that cardiovascular and/or respiratory responses produced by electrical or chemical stimulation of the CeA, IC, posterior portion of the anterior hypothalamus, dorsal periaqueductal gray and somatic nociceptors were reduced or completely blocked following inhibition of rostral medial and lateral PBN subnuclei (az-Casares et al 2009; Boscan et al 2005; Hayward 2007; Saleh and Connell 2003). Interestingly, the number of LH, CeA, dBNST and IC neurons retrogradely labeled in the present study did not differ as a function of PBN injection site (i.e.…”

Pre‐Bötzinger complex receives glutamatergic innervation from galaninergic and other retrotrapezoid nucleus neurons

“…We had some difficulty distinguishing the “lateral crescent” from the central subnucleus of the lateral parabrachial complex as originally defined (Fulwiler and Saper, 1984). Chemical stimulation of this general region of the parabrachial complex (presumably central and lateral crescent nuclei) causes hyperpnea and raises blood pressure and heart rate (Chamberlin and Saper, 1992; Chamberlin, 2004; Boscan et al, 2005). Such responses are also typically elicited by stimulation of central chemoreceptors and could plausibly also be elicited by the excitatory input from the RTN-Phox2b neurons to the lateral parabrachial region.…”

“…The lateral crescent and neighboring lateral parabrachial subnuclei also receive input from the C1 neurons of the ventrolateral medulla and from neurons located within the superficial laminae of the spinal cord that relay nociceptive stimuli (Boscan et al, 2005; Card et al, 2006). This convergence of inputs suggests that the lateral crescent or a nearby parabrachial region could be contributing to the arousal or alerting responses caused by a variety of intero- or extero-nociceptive inputs that converge on this region, including hypoxia and hypercapnia (Phillipson et al, 1977; Bowes et al, 1981).…”