Structure and function of the vomeronasal system: an update

Immunolocalization of G‐Protein Alpha Subunits in the Olfactory System of the Cartilaginous Fish Scyliorhinus Canicula

“…Similar data were obtained in histological In the literature the subunit Ga o has been shown to have different localizations according to the taxa considered but, generally, it is expressed in all or most of the microvillous RNs expressing either V1R or V2R receptor gene family. In mammals, Ga o is expressed by the V2R-VRN populations of the VE, projecting into the posterior part of the accessory OB (Berghard and Buck, 1996;Halpern and Martínez-Marcos, 2003) and the same has been found for Xenopus laevis (Hagino-yamagishi et al, 2004). In teleost (where the vomeronasal epithelium is lacking) the immunolocalization of Ga o in the olfactory epithelium can vary according to the species; in Neogobius melanostomus Ga o -like ir is localized in the microvillous RNs (while the ciliated ones express Ga s/olf ) and in CNs (Belanger et al, 2003); in goldfish Ga o -like ir is highlighted in most of the microvillous V2R-RNs, the CNs (that express also the Gaq) and in a substantial part of the olfactory nerve (Hansen et al, 2004).…”

“…Their sensory epithelia are differentially located in tetrapods, while, in fish, the two systems share the same localization and thence epithelium (Hansen et al, 2003(Hansen et al, , 2004. In mammals, the receptor neurons (RNs) in the olfactory epithelium (OE) express receptors of the olfactory receptor (OR) gene family, whereas the RNs in the vomeronasal epithelium (VE) express receptors of the vomeronasal receptors 1 and 2 (V1R and V2R) gene families (Buck and Axel, 1991;Dulac and Axel, 1995;Dryer, 2000;Halpern and Martínez-Marcos, 2003). In fish, all the receptor gene families are expressed by the RNs located into the same, unique OE (Hansen et al, 2003(Hansen et al, , 2004.…”

“…Moreover, a correlation between the morphology of the RN and the family of the expressed receptor molecule has been demonstrated in many species (Sato and Suzuki, 2001;Lipschitz and Michel, 2002;Halpern and Martínez-Marcos, 2003;Hansen et al, 2003Hansen et al, , 2004Einsthen, 2004;Hansen and Zielinski, 2005;Vielma et al, 2008). The receptor molecules belong to the gene superfamily GPCRs (G-protein coupled receptors).…”

“…The receptor molecules belong to the gene superfamily GPCRs (G-protein coupled receptors). Different types of G-protein have been shown to have a functional co-expression with different receptor molecules; in particular the distribution of different G-protein alpha subunits have been described in the olfactory/vomeronasal system of vertebrates (Takigami et al, 2000;Belanger et al, 2003;Halpern and Martínez-Marcos, 2003;Hansen et al, 2003Hansen et al, , 2004.…”

“…The RNs expressing the same receptor molecule, project their axons to the same glomerulus, synapsing with few mitral cells (Takigami et al, 2000;Firestein, 2001). Thus it has been suggested that, in the olfactory/vomeronasal system of a vertebrate, the localization of a RN, its morphology, the receptor gene family it expresses, the G-protein subtype coupled with this receptor, and the zone of projection to the OB are somehow correlated (Halpern and Martínez-Marcos, 2003;Hansen et al, 2004).…”