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.

Fluoxetine effects on periodontogenesis: histomorphometrical and immunohistochemical analyses in rats

“…The presence of serotonin in the sympathetic nerve fibers of the periodontal ligament reinforces the relationship of this neurotransmitter with the morphogenesis and homeostasis of oral structures 26 . Since the serotonin system has a regulatory function in the morphogenetic processes of neural and non-neural tissues, including enamel and dentin 10 and as periodontal tissues have been found to be sensitive to fluoxetine 5 , it is possible that early exposure to this drug may interfere in periodontogenesis.…”