mise à jour
1 avril 2004
Neuroscience letters
1997; 232; 63-66
 The paraventricular nucleus of the hypothalamus influences respiratory timing and activity in the rat
E Yeh, B Erokwub, J LaMannaa, M. Haxhiu
Department of Neurology, School ofMedicine (BRB), Case Western Reserve University, Cleveland, USA
Tous les travaux de MR Melis & A Argiolas 
Tous les travaux de M Eguibar & G Holmgren


The paraventricular nucleus (PVN), a cell group located bilaterally along the third ventricle, regulates neuroendocrine and cardiovascular functions, and modulates sympathetic outflow. Because many stimuli that influence sympathetic activity also affect breathing, it might be expected that stimulation of the PVN would change ventilation. Hence, the aim of this study was, first to examine whether activation of PVN neurons results in changes in respiratory output and pattern of breathing, and second to determine the connections between PVN and phrenic motoneurons through which PVN neurons might influence respiration.
The present study indicates that PVN can exert excitatory influences on respiratory drive. This effect can be mediated through PVN-brainstem and/or PVN-spinal cord pathways. In a previous study using the retrograde transneuronal marker, pseudorabies virus (PRV), we had shown that PVN was consistently labeled when the PRV was injected into the right hemidiaphragm of C8-T1 spinalectomized rats after ipsilateral cervical vagotomy, or in phrenic nerve. Because, PRV infects also the second order neurons, the results of the present study indicate the presence of direct projection from PVN to the phrenic motoneurons, and extend earlier studies related to connectivity of PVN with brainstem and spinal cord autonomic nuclei.
Physiologically, the present study demonstrated for the first time that activation of the PVN significantly influenced the magnitude of DEmG and the respiratory timing, which could be mediated by two pathways: (1) through the brainstem bulbospinal and, (2) probably via the direct connection with phrenic nucleus.
Although there are few physiological studies relating activation of PVN and respiration, Ferguson et al. have indirectly inferred through electrical stimulation of the subfornical organ that the changes in the respiratory pattern observed were mediated through the medullary center via the PVN. The relatively long changes in respiratory pattern observed following the injection of L-glutamate into PVN could be attributed to PVN's projection (possibly through vasopressin and oxytocin), to brainstem respiratory related cells, and to phrenic motoneurons.
In summary, the results of this study indicate that the changes in breathing activity associated with activation of the PVN neurons are part of complex responses as a consequence of activation of a network controlling autonomic, neuroendocrine, cardiovascular, and respiratory functions.