American Journal of Respiratory Medicine

, Volume 2, Issue 1, pp 21–29

Serotonin Agonists and Antagonists in Obstructive Sleep Apnea

Therapeutic Potential
Leading Article

DOI: 10.1007/BF03256636

Cite this article as:
Veasey, S.C. Am J Respir Med (2003) 2: 21. doi:10.1007/BF03256636

Abstract

Obstructive sleep apnea hypopnea syndrome (OSAHS) is a prevalent disorder associated with substantial cardiovascular and neurobehavioral morbidity. Yet this is a disorder for which there are no widely effective pharmacotherapies. The pathophysiology of obstructive sleep apnea namely, normal respiration in waking with disordered breathing only in sleep, suggests that this disorder should be readily amenable to drug therapy. Over the past 10 years, we have gained tremendous insight into the neurochemical mechanisms involved in state-dependent control of respiration. It is apparent from this work that there are many potential avenues for pharmacotherapies, including several seemingly conflicting directions for serotonergic therapies.

Serotonin delivery is reduced to upper airway dilator motor neurons in sleep, and this contributes, at least in part, to sleep-related reductions in dilator muscle activity and upper airway obstruction. The dilator motor neuron post-synaptic serotonin receptors are 5-HT2A and 5-HT2C subtypes, and in adults the presynaptic 5-HT receptor in motor nuclei is 5-HT1B, an inhibitory receptor. Serotonin receptors are also found within central respiratory neuronal groups, and these receptor subtypes include 5-HT1A (inhibitory) and 5-HT2 receptors. Peripherally, stimulation of 5-HT2A, 5-HT2C and 5-HT3 receptor subtypes have an inhibitory effect on respiration via action at the nodose ganglion. Many of these receptor subtypes and their signal transduction pathways may be affected by oxidative stress in obstructive sleep apnea. These alterations will make finding drug therapies for sleep apnea more challenging, but not insurmountable. Future directions are suggested for elucidating safe, well-tolerated serotonergic drugs for this disorder.

Tryptophan was one of the first serotonergic drugs tested for OSAHS. This drug was withdrawn from the market as a result of reports linking tryptophan use with eosinophilic myalgia syndrome and life-threatening pulmonary hypertension. Newer drugs with serotonergic activity tested in persons with sleep-disordered breathing include buspirone, fluoxetine and paroxetine. Trials are presently being conducted to evaluate the effects of 5-HT2A and 5-HT3 antagonists on OSAHS. Many of the drugs tested have not shown significant improvement in sleep apnea. However, with continued effort to elucidate the pharmacology of neurochemical control of state-dependent changes in respiratory control, the availability of pharmacological therapy for this disorder is not too far away.

Copyright information

© Adis International Limited 2003

Authors and Affiliations

  1. 1.Division of Sleep Medicine/Department of Medicine, Center for Sleep and Respiratory NeurobiologyUniversity of Pennsylvania, Hospital of the University of PennsylvaniaPhiladelphiaUSA

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