Abstract
The intrathecal (i.th., T8-10) administration in conscious rats of the 5-hydroxytryptamine (5-HT)1A agonist 8-OH-DPAT (10 nmol), and to a lesser extent the 5-HT1B agonist CGS 12066B (6 nmol), resulted in a blood pressure reduction and a bradycardia. These responses were prevented by the i.th. pretreatment with substance P (SP) (6.5 nmol) and enhanced following pretreatment with the non-peptide SP antagonist CP-96,345 (10 nmol). The partial 5-HT1A agonist 8-MeO-CLEPAT (10 nmol) had by itself small cardiovascular effects. Following the pretreatment with SP, 8-MeO-CLEPAT caused a pressor response and a tachycardia whereas the opposite effects were observed following pretreatment with the SP antagonist. These results support the notion of a functional interaction between serotonergic and SP mechanisms at the level of the preganglionic sympathetic nerves in the spinal cord.
MeSH terms
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8-Hydroxy-2-(di-n-propylamino)tetralin / administration & dosage
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8-Hydroxy-2-(di-n-propylamino)tetralin / pharmacology*
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Animals
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Biphenyl Compounds / administration & dosage
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Biphenyl Compounds / pharmacology*
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Blood Pressure / drug effects*
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Heart Rate / drug effects*
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Hypnotics and Sedatives / pharmacology
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Injections, Spinal
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Male
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Quinoxalines / administration & dosage
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Quinoxalines / pharmacology*
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Rats
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Rats, Sprague-Dawley
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Receptors, Serotonin / drug effects
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Receptors, Serotonin / physiology*
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Serotonin Receptor Agonists / administration & dosage
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Serotonin Receptor Agonists / pharmacology
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Spinal Cord / drug effects
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Spinal Cord / physiology*
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Substance P / administration & dosage
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Substance P / antagonists & inhibitors
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Substance P / pharmacology*
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Tetrahydronaphthalenes / administration & dosage
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Tetrahydronaphthalenes / pharmacology
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Time Factors
Substances
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Biphenyl Compounds
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Hypnotics and Sedatives
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Quinoxalines
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Receptors, Serotonin
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Serotonin Receptor Agonists
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Tetrahydronaphthalenes
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CGS 12066B
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8-methoxy-2-(N-2-chloroethyl-N-n-propyl)aminotetralin
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Substance P
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8-Hydroxy-2-(di-n-propylamino)tetralin
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CP 96345