EXPRESSION OF OLFACTORY RECEPTOR AND TRANSDUCTION GENES DURING RAT DEVELOPMENT

The molecular components of olfactory reception and regulation are exp ressed in a tissue-specific manner. The functional attributes mediated by some of these proteins have been previously shown to display a wel l-defined developmental emergence during the last week of rat gestatio n. To gain a better understanding of the relations between chemosensor y function and neuronal development, we studied the ontogeny of 7 olfa ctory-specific genes by quantitative PCR. Relative levels of expressio n during rat development were determined for each gene, starting at em bryonic day 15 (E15) and ending at postnatal day 35 (P35). In addition , the level of expression of the different genes was quantified in juv enile rats. The onset of expression for olfactory receptors and the ol factory cation channel at embryonic day 19 (E19) coincides with the fu nctional maturation of the sensory neurons. Olfactory G-protein and ad enylyl cyclase are expressed earlier (approximately E16) while olfacto ry biotransformation enzymes appear later (E20-E21), just before birth . The sequence of developmental expression of olfactory receptor genes has possible implications to the establishment of neuronal connectivi ty in this sensory pathway.