The use of brain slices and dissociated neurones to explore the multiplicity of actions of 5-HT in the central nervous system.
The cellular actions of 5-hydroxytryptamine (5-HT) on adult and neonatal rat central neurones have been investigated in detail using a combination of in vitro slice and dissociated neurone preparations. Patch-clamp recordings from acutely dissociated adult rat dorsal raphe neurones confirm data obtained using conventional slice preparations that 5-HT activates an inwardly rectifying potassium channel through a 5-HT1A receptor leading to hyperpolarization of the cell. Single-channel recordings indicate that this pathway requires only the involvement of a pertussis toxin-sensitive G-protein. Adult rat facial motoneurones in conventional slices are depolarized by 5-HT through a combination of mechanisms, closure of potassium channels and enhancement of the hyperpolarization-activated, cationic current, IH. Distinct receptors appear to mediate these two actions. Both mechanisms are present in visually indentified neonatal rat facial motoneurones in thin brain slices. Whole-cell patch-clamp recordings show the action of 5-HT on IH to mediate a caesium-sensitive inward current which can be mimicked by the adenylate cyclase activator, forskolin. The experimental data illustrate how a range of complimentary in vitro electrophysiological techniques can be employed to unravel neurotransmitter mechanisms and pharmacology.
D000818:Animals; D000831:Animals, Newborn; D001921:Brain / Q000187:drug effects; D002490:Central Nervous System / Q000187:drug effects*; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects; D009474:Neurons / Q000502:physiology; D018408:Patch-Clamp Techniques / Q000379:methods*; D051381:Rats; D011919:Rats, Inbred Strains; D012701:Serotonin / Q000494:pharmacology*; D013126:Spinal Nerve Roots / Q000187:drug effects
D012701:Serotonin