title: Age-dependent changes in serotonergic modulation of yawning in the rat.
abstract: Serotonin (5-HT) effects on physostigmine (PHY)-induced yawning were studied in LY Sprague-Dawley rats by injecting Lu 10 171 (citalopram), a specific 5-HT uptake blocker, and two antagonists--methiothepine and ritanserin--which differ slightly in the selectivity of their actions on different 5-HT receptor subtypes. Infant and young rats show significant increases in PHY-induced yawning when preinjected with citalopram (5-10 mg/kg). Two-month-old animals show this effect only with 10 mg/kg. With adult animals (3-5 months old), the effect is the opposite: Yawning decreases. The facilitory effect in infant and young rats was counteracted by methiothepine but not by ritanserin, suggesting that it is mediated through 5-HT1A or 5-HT1B receptor subtypes. The inhibitory effect of citalopram in adult rats was unmodified by the two antagonists used, leaving open the possibility that it is mediated by 5-HT3 receptors.
authors.affiliation: Departamento de Ciencias Fisiologicas, Universidad Autonoma de Puebla, Mexico.
authors.forename: R
authors.initials: R
authors.lastname: Urbá-Holmgren
authors.forename: B
authors.initials: B
authors.lastname: Holmgren
authors.forename: B A
authors.initials: BA
authors.lastname: Leon
authors.forename: A
authors.initials: A
authors.lastname: Ugarte
mesh_terms: D000375:Aging / Q000523:psychology*; D000818:Animals; D015283:Citalopram / Q000494:pharmacology; D008297:Male; D008719:Methiothepin / Q000494:pharmacology; D010830:Physostigmine / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D016713:Ritanserin / Q000494:pharmacology; D012701:Serotonin / Q000502:physiology*; D012702:Serotonin Antagonists / Q000494:pharmacology; D015000:Yawning / Q000502:physiology*
chemical_list: D012702:Serotonin Antagonists; D015283:Citalopram; D016713:Ritanserin; D012701:Serotonin; D008719:Methiothepin; D010830:Physostigmine