EXPRESSION OF A SEROTONIN-GATED ION-CHANNEL IN EMBRYONIC NEURAL AND NONNEURAL TISSUES

The neurotransmitter serotonin (5HT) has been implicated in morphogene sis of central nervous system and craniofacial structures. The actions of serotonin are mediated by multiple receptor subtypes, one of which , the 5HT(3) receptor, is a ligand-gated ion channel. To determine whe ther this channel may contribute to the proposed morphogenic actions o f serotonin, the expression of 5HT(3) receptor transcripts was examine d during mouse embryogenesis and correlated with the distribution of s erotonin transporter mRNA and serotonin immunoreactivity, The pattern of 5HT(3) receptor mRNA expression within the brain suggests possible roles for this receptor in the proliferation, differentiation, or migr ation of CNS neurons. In the peripheral nervous system, 5HT(3) recepto r transcripts were observed within cranial nerve sensory ganglia, olfa ctory neuroepithelia, and sympathoadrenal and enteric nervous systems during the initial stages of their formation. Striking expression of 5 HT(3) receptor transcripts occurred outside the nervous system, in ass ociation with regions of active chondrogenesis in the vertebral column , limbs, and craniofacial region, suggesting a possible involvement of this receptor subtype in the morphogenesis of olfactory receptor neur ons, teeth, and genitalia. (C) 1995 Academic Press, Inc.