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Differential effects of 5‐HT on neurones in the central autonomic area of rat thoracic spinal cord.
Author(s) -
Poole Sarah Louise,
Deuchars Jim,
Deuchars Susan A
Publication year - 2007
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.21.6.a885
Subject(s) - spinal cord , 5 ht receptor , chemistry , depolarization , agonist , disinhibition , patch clamp , serotonin , neuroscience , membrane potential , receptor , anatomy , medicine , endocrinology , biology
5‐HT containing terminals and fibers innervate the central autonomic area (CAA) of the thoracic spinal cord (Krukoff et al 1985 J. Comp Neurol , 240 , 103–116). Dense labeling for the 5‐HT2A receptor is also present within the CAA (Doly et al 2004, J. Comp Neurol , 472 , 496–511). Therefore the effect of 5‐HT upon neurones in the CAA was investigated. Wistar rats (11 days old) or transgenic reporter GAD‐65‐GFP mice (8–21 days) were anaesthetized with urethane and whole‐cell patch clamp recordings made from neurones in 300μm transverse slices of thoracic spinal cord. Neurones in the CAA were either depolarized (+10.4±0.7mV, 20μM, n=4) or hyperpolarized (−5.7±1.13mV, 20μM, n=6 and −3.5±1.0mV, 10μM, n=2) by 5‐HT. Neurons that were hyperpolarized expressed a sag in the membrane potential in response to hyperpolarizing current pulses (8/8) indicative of activating an Ih. Those that were depolarized expressed either an Ih (2/4) or a delay in return to resting membrane potential indicative of activating an IA (2/4). Both depolarizing (n=1/1) and hyperpolarizing (n=3/3) responses to 5‐HT were mimicked by the 5‐HT2 receptor agonist α‐methyl‐5HT. In preliminary recordings a GAD‐65 neuron in the CAA was hyperpolarized by 5HT (20μM). This data may suggest that GABAergic interneurons in the CAA are predominantly inhibited by 5HT, leading to disinhibition and increased sympathetic outflow. Supported by the British Heart Foundation