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Role of 5‐HT2 receptors in modulating cardio‐respiratory interactions in the brainstem
Author(s) -
Dergacheva Olga Y,
Mendelowitz David
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.5.a1202-a
Subject(s) - ketanserin , 5 ht2 receptor , receptor , gabaergic , neurotransmission , 5 ht receptor , agonist , neuroscience , serotonergic , medicine , endocrinology , chemistry , biology , serotonin , pharmacology
Bradycardia is an important pathophysiological component of sudden infant death syndrome (SIDS). Serotonergic pathways and receptors, particularly 5‐HT2 receptors, are also likely involved in SIDS. This study examines whether 5‐HT2 receptors alters parasympathetic cardiac activity by modulating GABAergic neurotransmission to cardiac vagal neurons (CVNs) within the nucleus ambiguus (NA). CVNs of Sprague‐Dawley rats were studied using the whole‐cell patch‐clamp technique in 800 μm slices with an intact hypoglossal nerve rootlet. To examine whether 5‐HT2 receptors modulate GABAergic synaptic activity the 5‐HT2 receptor agonist á‐methyl‐5HT (1 μM) was applied by inclusion in the perfusate with or without the 5‐HT2A/2C receptor antagonist ketanserin (1 μM). Multiple applications á‐methyl‐5HT (3 applications of 4‐min duration every 9 min), but not a single 4‐min application, decreased the frequency of both spontaneous and respiratory‐related GABAergic IPSCs. However, in the present of ketanserin both single and multiple applications diminished spontaneous as well as respiratory‐related GABAergic IPSCs. This study demonstrates multiple activation of 5‐HT2 receptors elicits an inhibition of GABAergic neurotransmission. When 5‐HT2A/2C receptors are blocked by ketanserin the effect of remaining 5‐HT2 receptors activated by á‐methyl‐5HT also elicit inhibition to a single expose. These finding are relevant to mechanisms of 5‐HT2 receptor induced bradycardia which may play a role in SIDS.