The role of central 5‐HT1A receptors in the control of B‐fibre cardiac and bronchoconstrictor vagal preganglionic neurones in anaesthetized cats
- 1 November 2001
- journal article
- Published by Wiley in The Journal of Physiology
- Vol. 536 (3), 753-767
- https://doi.org/10.1111/j.1469-7793.2001.00753.x
Abstract
1. Experiments were performed to determine whether 5-HT(1A) receptors (a) modulate the activity of cardiac and bronchoconstrictor vagal preganglionic neurones (CVPNs and BVPNs) in the nucleus ambiguus (NA) and (b) are involved in pulmonary C-fibre afferent-evoked excitation of CVPNs, by right-atrial injections of phenylbiguanide (PBG). These experiments were carried out on alpha-chloralose-anaesthetized, artificially ventilated and atenolol (1 mg kg(-1))-pretreated cats. 2. The ionophoretic application of 8-OH-DPAT (a selective 5-HT(1A) receptor agonist) influenced the activity of 16 of the 19 CVPNs tested. 8-OH-DPAT tended to cause inhibition at low currents (40 nA) and excitation at high currents (120 nA). The activity of 15 of these neurones increased in response to the application of 8-OH-DPAT. In six of the CVPNs tested, this excitatory action of 8-OH-DPAT was attenuated by co-application of the selective 5-HT(1A) receptor antagonist WAY-100635. 3. The pulmonary C-fibre afferent-evoked excitation of eight CVPNs was attenuated by ionophoretic application of WAY-100635. 4. In three out of four CVPNs, the ionophoretic application of PBG caused excitation. 5. In five out of the nine identified BVPNs that were tested with ionophoretic application of 8-OH-DPAT, excitation was observed that was attenuated by WAY-100635. 6. WAY-100635 (I.V. or intra-cisternally) also reversed bradycardia, hypotension and the decrease in phrenic nerve activity evoked by the I.V. application of 8-OH-DPAT (42 microg kg(-1)). 7. In conclusion, the data indicate that 5-HT(1A) receptors located in the NA play an important role in the reflex activation of CVPNs and BVPNs, and support the view that overall, these receptors play a fundamental role in the reflex regulation of parasympathetic outflow.This publication has 51 references indexed in Scilit:
- The role of α1‐adrenoceptors and 5‐HT1A receptors in the control of the micturition reflex in male anaesthetized ratsBritish Journal of Pharmacology, 2001
- Effect of pulmonary C‐fibre afferent stimulation on cardiac vagal neurones in the nucleus ambiguus in anaesthetized catsThe Journal of Physiology, 2000
- Modulation of the vagal bradycardia evoked by stimulation of upper airway receptors by central 5-HT1 receptors in anaesthetized rabbitsBritish Journal of Pharmacology, 1998
- Presynaptic 5-HT3receptors evoke an excitatory response in dorsal vagal preganglionic neurones in anaesthetized ratsThe Journal of Physiology, 1998
- Neurochemical modulation of cardiovascular control in the nucleus tractus solitariusProgress in Neurobiology, 1996
- Localization of cardiac vagal preganglionic motoneurones in the rat: Immunocytochemical evidence of synaptic inputs containing 5‐hydroxytryptamineJournal of Comparative Neurology, 1993
- Additive effects of dopamine and 8-OH-DPAT microinjected into the nucleus ambiguus in eliciting vagal bradycardia in ratsJournal of the Autonomic Nervous System, 1992
- Differential modulation of three separate K-conductances in hippocampal CA1 neurons by serotoninNature, 1987
- Afferent vagal C fibre innervation of the lungs and airways and its functional significanceReviews of physiology, biochemistry and pharmacology, 1984
- GABA Receptor Control of Parasympathetic Outflow to Heart: Characterization and Brainstem LocalizationScience, 1979