5-HT2A receptor activation of the external urethral sphincter and 5-HT2C receptor inhibition of micturition: A study based on pharmacokinetics in the anaesthetized female rat
| Autor: | Yvonne Mbaki, Gordon McMurray, Jennifer C. Gardiner, Andrew G. Ramage |
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| Rok vydání: | 2012 |
| Předmět: |
Agonist
medicine.medical_specialty medicine.drug_class media_common.quotation_subject Urination Blood Pressure chemistry.chemical_compound Urethra Internal medicine Receptor Serotonin 5-HT2C medicine Animals Anesthesia Drug Interactions Receptor Serotonin 5-HT2A Muscle Skeletal Receptor 5-HT receptor media_common Pharmacology Electromyography Chemistry Urethral sphincter Receptor antagonist Rats 5-HT2C receptor Endocrinology Serotonin 5-HT2 Receptor Antagonists Female SB-242084 |
| Zdroj: | European Journal of Pharmacology. 682:142-152 |
| ISSN: | 0014-2999 |
| Popis: | Central and peripheral 5-hydroxytryptamine (5-HT) receptors play a critical role in the regulation of micturition. Bolus doses of 5-HT(2A/2C) receptor agonists have been shown to activate the external urethral sphincter (EUS) and to inhibit micturition. This study was designed to determine the contribution of these two 5-HT receptor subtypes to activation of the EUS and inhibition of micturition utilising pharmacokinetic knowledge to better control drug exposure. Recordings of urethral and bladder pressure, EUS-Electromyogram (EMG), the micturition reflex induced by bladder filling, blood pressure and heart rate were made in anaesthetized female rats. The effects of intravenous (i.v.) infusions of the 5-HT(2) receptor agonist (2S)-1-(6-chloro-5-fluoroindol-1-yl)propan-2-amine fumarate (Ro 60-0175) in the absence or presence of the selective 5-HT(2C) receptor antagonist 6-chloro-5-methyl-N-[6-(2-methylpyridin-3-yl)oxypyridin-3-yl]-2,3-dihydroindole-1-carboxamide dihydrochloride (SB 242084) or 5-HT(2A) receptor antagonist (R)-(2,3-dimethoxyphenyl)-[1-[2-(4-fluorophenyl)ethyl]piperidin-4-yl]methanol (MDL-100,907) were studied on these variables. Continuous infusion of increasing concentrations of Ro 60-0175 only evoked EUS-EMG activity at the highest concentration, which was blocked by co-infusion of MDL-100,907 but not SB 242084. Urethral pressure was unaffected by any drug infusion. Ro 60-0175 at the lowest concentration inhibited the micturition reflex but as the concentration increased this was reversed to facilitation. SB 242084 blocked the inhibition while MDL-100,907 blocked the excitation. Activation of 5-HT(2A) not 5-HT(2C) receptors evoked EUS-EMG activity. In conclusion, 5-HT(2A) receptor activation facilitated the micturition reflex and evoked EUS-EMG while 5-HT(2C) receptor activation only inhibited the micturition reflex. |
| Databáze: | OpenAIRE |
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