title: 5-Hydroxytryptamine-3 receptors modulate synaptic activity in the rat nucleus tractus solitarius in vitro.
abstract: Whole-cell patch clamp recordings were made from neurons in the rat nucleus tractus solitarius (NTS) in transverse brainstem slices. 5-Hydroxytryptamine (5-HT, 100 microM) and the selective 5-HT3 receptor agonist 2-methyl-5-HT (2-CH3-5-HT, 100 microM) depolarized 86% of NTS neurons at resting membrane potential (Vm). This response was resistant to tetrodotoxin (TTX) and Co2+ application. In addition, 2-CH3-5-HT (500 nM-100 microM) increased the amplitude and frequency of both excitatory and inhibitory spontaneous synaptic potentials. This effect was also TTX-resistant, but was abolished by Co2+. The effects of 2-CH3-5-HT on EPSPs and IPSPs evoked by electrical stimulation of the tractus solitarius (TS) were analyzed separately in the presence of bicuculline or 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), respectively. Concentrations of 2-CH3-5-HT between 500 nM and 1 microM decreased the amplitude of evoked EPSPs and IPSPs with similar potency. The selective 5-HT3 receptor antagonists ICS 205-930 (10 nM) and MDL 72222 (10 microM) reversibly blocked the effects of 2-CH3-5-HT at all doses examined. It is concluded that 5-HT3 receptors can mediate both pre- and postsynaptic responses in the NTS.
authors.affiliation: Department of Pharmacological and Physiological Sciences, University of Chicago, IL 60637.
authors.forename: S R
authors.initials: SR
authors.lastname: Glaum
authors.forename: P A
authors.initials: PA
authors.lastname: Brooks
authors.forename: K M
authors.initials: KM
authors.lastname: Spyer
authors.forename: R J
authors.initials: RJ
authors.lastname: Miller
mesh_terms: D000818:Animals; D004558:Electric Stimulation; D005071:Evoked Potentials / Q000187:drug effects / Q000502:physiology*; D005260:Female; D066298:In Vitro Techniques; D008297:Male; D008526:Medulla Oblongata / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011985:Receptors, Serotonin / Q000187:drug effects / Q000502:physiology*; D012701:Serotonin / Q000031:analogs & derivatives / Q000494:pharmacology; D013569:Synapses / Q000187:drug effects / Q000502:physiology*
chemical_list: D011985:Receptors, Serotonin; D012701:Serotonin