title: 5-Hydroxytryptamine immunoreactivity is detectable in sympathetic nerve fibres in rat oral tissues.
abstract: The aim of this investigation was to examine if 5-hydroxytryptamine (5-HT) is detectable not only in mast cells but also in sympathetic nerve fibres in oral sites of the rat, including the periodontal ligament, pulp, palatal mucosa, and vestibular sulcus. Antibodies against 5-HT and tyrosine hydroxylase were used. Maxillae from rats were dissected free, fixed, decalcified, cut transversally, and processed for immunohistochemistry. Nerve fibres showing 5-HT-like immunoreactivity were regularly observed in the walls of the arteries and arterioles in the vestibular sulcus and the periodontal ligament. However, 5-HT-like immunoreactivity was not seen in the walls of the vessels of the palatal mucosa. Interestingly, 5-HT-like immunoreactivity coexisted with tyrosine hydroxylase-like immunoreactivity in the innervation of the periodontal ligament and the vestibular sulcus. Thus, the present study gives morphological correlate for the occurrence of effects of 5-HT derived not only from mast cells but also from sympathetic nerve fibres in oral tissues. The source of 5-HT in the nerve fibres as well as the functional implications of the observations remain to be determined.
authors.affiliation: Department of Orthodontics, Umeå University, Sweden.
authors.forename: L I
authors.initials: LI
authors.lastname: Norevall
authors.forename: L
authors.initials: L
authors.lastname: Matsson
authors.forename: S
authors.initials: S
authors.lastname: Forsgren
mesh_terms: D000818:Animals; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect; D008407:Mast Cells / Q000378:metabolism; D009055:Mouth / Q000294:innervation*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012701:Serotonin / Q000032:analysis*; D013564:Sympathetic Nervous System / Q000378:metabolism*
chemical_list: D012701:Serotonin