Pulmonary hypertension and the serotonin hypothesis: where are we now?
In the 1960s, serotonin (5HT) was associated with pulmonary arterial hypertension (PAH) caused by certain diet pills, but has recently been the subject of renewed interest in the field of PAH. Serotonin can be synthesised in the pulmonary endothelium with the rate-limiting step being the activity of tryptophan hydroxylase1 (Tph1). The serotonin is released and can then: (i) pass into the underlying pulmonary smooth muscle cells through the serotonin transporter (SERT) to initiate proliferation and/or (ii) activate serotonin receptors on pulmonary smooth muscle cells to evoke proliferation and/or contraction. Serotonin may also mediate pulmonary fibroblast proliferation via the SERT and/or serotonin receptors. Here we will unravel, discuss and update the 'serotonin hypothesis' of PAH in light of recent advances in the field. In conclusion, the activity of serotonin receptors, the SERT and Tph1 can all be elevated in clinical and experimental PAH and each offers a potentially unique therapeutic target.
Division of Neuroscience and Biomedical Systems, University of Glasgow, Glasgow, UK. m.maclean@bio.gla.ac.uk
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MacLean
D020372:Dexfenfluramine / Q000009:adverse effects; D006801:Humans; D006976:Hypertension, Pulmonary / Q000209:etiology* / Q000378:metabolism; D015221:Potassium Channels; D011985:Receptors, Serotonin / Q000145:classification / Q000502:physiology; D012701:Serotonin / Q000378:metabolism / Q000502:physiology*; D050486:Serotonin Plasma Membrane Transport Proteins / Q000502:physiology; D017366:Serotonin Receptor Agonists / Q000009:adverse effects; D014365:Tryptophan Hydroxylase / Q000235:genetics
D015221:Potassium Channels; D011985:Receptors, Serotonin; D050486:Serotonin Plasma Membrane Transport Proteins; D017366:Serotonin Receptor Agonists; D012701:Serotonin; D020372:Dexfenfluramine; C497467:TPH1 protein, human; D014365:Tryptophan Hydroxylase