EMBRYONIC EXPRESSION OF THE 5-HT3 RECEPTOR SUBUNIT, 5-HT(3)R-A, IN THE RAT - AN IN-SITU HYBRIDIZATION STUDY

The role of serotonin as a neurotransmitter in the vertebrate central and peripheral nervous systems has been extensively studied. In additi on to its well-defined role in neurotransmission, serotonin has also b een implicated in development. We have used in situ hybridization to l ocalize 5-HT3 receptor mRNA in embryonic rat sections from Embryonic D ay 10 (E10) to E18. Expression was first detected in the cranial senso ry ganglia starting on E10. Expression was later detected in many regi ons within the developing CNS. In addition to the cranial sensory gang lia, expression was detected in many regions of the peripheral nervous system including dorsal root, sympathetic, and parasympathetic gangli a, and in the myenteric plexus of the enteric nervous system. Expressi on was also detected in many nonneuronal cell populations including th e choroid plexus, cochlear duct, and olfactory epithelium. Expression in regions of active epithelial-mesenchymal interaction such as the to oth bud, lung, and submandibular grand may indicate a role for 5-HT3 r eceptors in the process of secondary induction. (C) 1995 Academic Pres s Press, Inc.