Role of the parabrachial complex in the cardiorespiratory response evoked from hypothalamic defense area stimulation in the anesthetized rat

• Published in: Brain research Vol. 1279; pp. 58 - 70
• Main Authors: Díaz-Casares, Amelia, López-González, Manuel Víctor, Peinado-Aragonés, Carlos Antonio, Lara, José Pablo, González-Barón, Salvador, Dawid-Milner, Marc Stefan
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 07-07-2009; Elsevier
• Subjects: Action Potentials; Anesthesia; Animals; Biological and medical sciences; Blood Pressure - physiology; Brain Stem - drug effects; Brain Stem - physiology; Cardiovascular control; Electric Stimulation; Fundamental and applied biological sciences. Psychology; GABA Agonists - pharmacology; Heart Rate - physiology; Hypothalamic defense area; Hypothalamus - physiology; Kölliker-Fuse; Male; Microelectrodes; Microinjections; Motor control and motor pathways. Reflexes. Control centers of vegetative functions. Vestibular system and equilibration; Muscimol - pharmacology; Neural Pathways - drug effects; Neural Pathways - physiology; Neurology; Neurons - physiology; Parabrachial complex; Rat; Rats; Rats, Sprague-Dawley; Respiration; Respiratory control; Vertebrates: nervous system and sense organs; Hypothalamic defense area; Parabrachial complex; Cardiovascular control; Kölliker-Fuse; Rat; Respiratory control; Rodentia; Central nervous system; Stimulation; Hypothalamus; Encephalon; Parabrachial nucleus; Vertebrata; Mammalia; Animal; Respiration
• ISSN: 0006-8993; 1872-6240
• DOI: 10.1016/j.brainres.2009.02.085

Abstract To analyze the role of parabrachial complex (PBc) in the modulation of cardiorespiratory response evoked from the hypothalamic defense area (HDA), cardiorespiratory changes were analyzed in spontaneously breathing anesthetised rats in response to electrical stimulation of the HDA (1 ms pulses, 30–50 μA, 100 Hz for 5 s) before and after the microinjection of muscimol (50 nl, 0.25 nmol, 5 s) within the PBc. HDA stimulation evoked an inspiratory facilitatory response, consisting of an increase in respiratory rate ( p < 0.001) due to a decrease in expiratory time ( p < 0.01). The respiratory response was accompanied by a pressor ( p < 0.001) and a tachycardic ( p < 0.001) response. Muscimol microinjection within the lateral parabrachial region (lPB) abolished the respiratory response to HDA stimulation ( p < 0.01) and decreased the pressor response ( p < 0.05). Muscimol within the medial parabrachial region and Kölliker-Fuse (mPB-KF) decreased the magnitude of the pressor ( p < 0.01) and tachycardic ( p < 0.05) responses to HDA stimulation. The respiratory response persisted unchanged. Finally, extracellular recording of putative neurons from these regions were obtained during HDA stimulation to confirm functional interaction between HDA and parabrachial regions. 105 pontine cells were recorded during HDA stimulation, 57 from the lPB and 48 from the mPB-KF. In mPB-KF 34/48 (71%) and in lPB 38/57 (67%) cells were influenced from HDA. The results indicate that neurons from different regions of the PBc have an important function in mediating the cardiorespiratory response evoked from the HDA. The possible mechanisms involved in these interactions are discussed.