Current research involves studies of the neural mechanisms involved in the control of brainstem motoneurons that innervate upper airway muscles, particularly in reference to the control of the upper airway during rapid eye movement (REM) sleep and sleep-disordered breathing. For this, we use a urethane-anesthetized rat model in which REM sleep-like episodes are elicited by microinjections of carbachol (a cholinergic agonist) into a distinct site in the dorsal pontine tegmentum. These episodes can be triggered repeatedly and comprise events typical of REM sleep, such as cortical activation, hippocampal theta rhythm, silencing of pontine adrenergic neurons, slowing of the respiratory rate, and suppression of postural and upper airway motoneuronal activity. The role of the adrenergic (noradrenaline and serotonin) systems of the brainstem in the control of upper airway motoneurons (hypoglossal, pharyngeal, laryngeal), and its relation to REM sleep atonia, is currently being investigated using a variety of complementary neurophysiological, neuropharmacological and neuroanatomical techniques.
Fenik, V., H. Ogawa, R.O. Davies and L. Kubin. Carbachol injections into the ventral pontine reticular formation activate locus coeruleus cells in urethane-anesthetized rats Sleep 28: 560-570, 2005.Fenik, V.B., M. Malinowska, R.O. Davies and L. Kubin. Medullary control of the upper airway during REM sleep Clinical and Neurophysiological Aspects of Sleep : 47-53, 2005.Fenik, V.B., R.O. Davies and L. Kubin Noradrenergic, serotonergic and GABAergic antagonists injected together into the XII nucleus abolish the REM sleep-like depression of hypoglossal motoneuronal activity Journal of Sleep Research 14: 419-429, 2005.Fenik, V.B., R.O. Davies and L. Kubin. REM sleep-like atonia of hypoglossal (XII) motoneurons is caused by loss of noradrenergic and serotonergic inputs. American Journal of Respiratory Critical Care Medicine 172: 1322-1330, 2005.Volgin, D.V.,V.B. Fenik, R. Fay, S. Okabe, R.O. Davies and L. Kubin Serotonergic receptors and effects in hypoglossal and laryngeal motoneurons. Post-Genomic Perspectives in Modeling and Control of Breathing. : 183-188, 2004.Fenik, V., R.O. Davies and L. Kubin. Combined antagonism of aminergic and amino acid inhibitory receptors in the XII nucleus abolishes REM sleep-like depression of hypoglossal motoneuronal activity Arch. Ital. Biol., 142: 237-249, 2004.Kubin, L. and R.O. Davies. Mechanisms of airway hypotonia Pathogenesis, Diagnosis and Treatment of Sleep Apnea. : 99-154, 2002.Fenik, V. B., V. Marchenko, P. Janssen, R.O. Davies and L. Kubin A5 cells are silenced when REM sleep-like signs are elicited by pontine carbachol
Journal of Applied Physiology 93: 1448-1456, 2002.Woch, G., H. Ogawa, R.O. Davies and L. Kubin. Behavior of hypoglossal inspiratory premotor neurons during the carbachol-induced, REM sleep-like suppression of upper airway motoneurons Brain Research 130: 508-520, 2000.Fenik, V., R.O. Davies, A.I. Pack and L. Kubin Differential suppression of upper airway motor activity during carbachol-induced, REM sleep-like atonia American Journal of Physiology 275: R1013-R1024, 1998.