Key result
5-HT inhibited increases in perfusion pressure induced by electrical stimulation of the lumbar chains by acting on presynaptic 5-HT1D receptors to decrease noradrenaline release.
5-HT inhibits neurogenic vasoconstriction in the rat hindquarter vascular bed by acting on presynaptic 5-HT1D receptors to decrease noradrenaline release.
Hypothesis-generating for 5-HT1D modulation of sympathetic vasoconstriction in rodents; leaves open human translation.
In the present study, we analysed the effect of different doses of 5-hydroxytryptamine (5-HT; intravenous infusions of 0.001-40 microg/kg per min) in the autoperfused hindquarters of the rat subjected to electrical stimulation (frequencies of 0.5-20 Hz) of the lumbar chains, investigating the relationship between the adrenergic and serotonergic systems in this vascular bed. 2. Because we observed that 5-HT inhibited the increases in perfusion pressure induced by electrical stimulation of the lumbar chains, we used different agonists and antagonists to analyse the mechanism of action of 5-HT. 3. The effect of 5-HT was inhibited by methiothepin (a non-specific 5-HT receptor antagonist), but not by ritanserin (a selective 5-HT2 receptor antagonist). The effects of 5-HT were mimicked by 5-carboxamidotryptamine (a 5-HT1 receptor agonist) and L-694 247 (a selective 5-HT1D receptor agonist), but not by 8-hydroxy-2-dipropylaminotetralin (a 5-HT1A receptor agonist), CGS-12066B (a 5-HT1B receptor agonist), alpha-methyl-5-HT (a 5-HT2 receptor agonist), 1-(3-chlorophenyl) piperazine (a 5-HT2C receptor agonist) or 1-phenylbiguanide (a 5-HT3 receptor agonist). The selective 5-HT1D/1B receptor antagonist BRL 15572 inhibited the effect of the agonist L-694 247. 4. Our data suggest that 5-HT inhibits the increases in perfusion pressure induced by the electrical stimulation of the lumbar chains, acting on presynaptic 5-HT1D receptors and decreasing the release of noradrenaline from the sympathetic nerves in the hindquarter vascular bed of the rat.
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Calama et al. (2005) studied this question. 5-hydroxytryptamine (5-HT) was evaluated on Increases in perfusion pressure induced by electrical stimulation of the lumbar chains. 5-HT inhibited increases in perfusion pressure induced by electrical stimulation of the lumbar chains by acting on presynaptic 5-HT1D receptors to decrease noradrenaline release.
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