Olfaction Flashcards
What is the olfactory habituation/diahabituation test
Used to test whether the animal can detect and differentiate different odors
Relies on the animal’s tendency to investigate novel smells
What are the previous results from olfaction in the Wells lab
redox-sensitive transcription factors such nuclear factor erythroid-2-related factor 2 (Nrf2)
Meth -> ROS enhancing drug
Nrf2 KO –> mice were not able to habituate or discriminate between paprika and cinnamon
Meth exposure reduced the number of GABAergic neurons on the olfactory bulbs
he most fundamental division is between the main and accessory olfactory systems
Olfactory sensory neurons (OSNs) of the main olfactory system are located in the main olfactory epithelium (MOE) and send their axons to synapse with second order neurons in the main olfactory bulb (Munger et al. 2009, Firestein 2001). In contrast, sensory neurons in the accessory system are found within the vomeronasal organ (VNO, which lies above the hard palate and at the base of the nasal septum); axons of these vomeronasal sensory neurons (VSNs) project to the accessory olfactory bulb
What is the protein strucutre of ORs
key hallmarks of GPCRs, including seven putative membrane-spanning helices, three putative intracellular and three putative extracellular loops connecting these helices, and a conserved DRY amino acid motif (a hallmark of GPCRs) within the second intracellular loop (Buck & Axel 1991, Mombaerts 2004a). The encoded proteins also contain hypervariable regions that likely contribute to selective binding of different odorants
How many ORs in humans vs. rodents
estimated that humans express ~350 functional ORs, while rodents express over 1000 (Buck & Axel 1991
A chemosensory role for many ORs has been confirmed through both in vitro and in vivo functional studies. ORs confer selective odor responsiveness on either OSNs [e.g., (Zhao et al. 1998, Bozza et al. 2002, Grosmaitre et al. 2006, Touhara et al. 1999)] or heterologous cells [e.g., (Krautwurst et al. 1998, Abaffy et al. 2006, Kajiya et al. 2001, Wetzel et al. 1999, Saito et al. 2009)]; thus, the OR dictates the stimulus tuning of the OSN. All of the ORs deorphaned to date respond to volatile odorants of diverse chemical classes, and most ORs are broadly tuned to multiple stimuli (Zhao et al. 1998, Krautwurst et al. 1998, Mombaerts 2004a, Abaffy et al. 2006). In addition, multiple ORs can respond to the same odorant, though usually with different efficacies (Malnic et al. 1999, Mombaerts 2004a). This is consistent with the observation that most OSNs recognize multiple odorants (Firestein 2001). Thus, odors are encoded using a combinatorial strategy employing multiple ORs of overlapping stimulus selectivity (Malnic et al. 1999, Buck 2000). Interestingly, some odors are OR antagonists (Shirokova et al. 2005, Spehr et al. 2003, Oka et al. 2004) and could therefore increase the complexity of odor coding.
