Differential localization of NT-3 and TrpM5 in glomeruli of the olfactory bulb of mice.

Olfactory sensory neurons that express transient receptor potential channel M5 (TrpM5) or neurotrophin-3 (NT-3) project to defined clusters of glomeruli situated ventrally in the main olfactory bulb. Using genetically labeled mice, we investigated whether expression of NT-3-driven βgal and TrpM5-driven GFP marked overlapping sets of glomeruli and whether expression of these markers was coordinated. Our results indicate that these markers largely characterize independent sets of olfactory sensory neuron axons and glomeruli.

Potential role of transient receptor potential channel M5 in sensing putative pheromones in mouse olfactory sensory neurons.

Based on pharmacological studies of chemosensory transduction in transient receptor potential channel M5 (TRPM5) knockout mice it was hypothesized that this channel is involved in transduction for a subset of putative pheromones in mouse olfactory sensory neurons (OSNs). Yet, in the same study an electroolfactogram (EOG) in the mouse olfactory epithelium showed no significant difference in the responses to pheromones (and odors) between wild type and TRPM5 knockout mice. Here we show that the number of OSNs expressing TRPM5 is increased by unilateral naris occlusion.

Bile salts are effective taste stimuli in channel catfish.

Bile salts are known olfactory stimuli for teleosts, but only a single report has indicated that the taste system of a fish was sensitive to this class of stimuli. Here, gustatory responses of the channel catfish, Ictalurus punctatus, to four bile salts that included taurine-, glycine- and non-conjugated compounds along with three stimulatory amino acids as a comparison were investigated using extracellular electrophysiological techniques. Integrated multiunit responses were obtained from the branch of the facial nerve innervating taste buds on the maxillary barbel.

Processing of bile salt odor information by single olfactory bulb neurons in the channel catfish.

A chemotopic map of biologically relevant odorants (that include amino acids, bile salts, and nucleotides) exists in the olfactory bulb (OB) of channel catfish, Ictalurus punctatus. Neurons processing bile salt odorant information lie medially within this OB map; however, information as to how single neurons process bile salt odorant information is lacking. In the present report, recordings were obtained from 51 OB neurons from 30 channel catfish to determine the excitatory molecular receptive range (EMRR) of bile salt responsive neurons.