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Behavioral phenotyping of mice with disrupted olfactory map

Behavioral phenotyping of mice with disrupted olfactory map. Oxana Litvine Yu lab. The olfactory system of rodent. Convergence of olfactory sensory neurons with the same receptors to a single glomerulus. Mombaerts et al., 1999.

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Behavioral phenotyping of mice with disrupted olfactory map

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  1. Behavioral phenotyping of mice with disrupted olfactory map Oxana Litvine Yu lab

  2. The olfactory system of rodent

  3. Convergence of olfactory sensory neurons with the same receptors to a single glomerulus Mombaerts et al., 1999

  4. Convergence of OSN to single glomeruli plays role in coding and processing of odor molecule information: olfactory spatial code Representation of odorants in olfactory bulb: similar odorants activate neighboring glomeruli Presentation of odorants with similar chemical structure Amyl acetate (banana smell) activates stereotypic set of glomeruli in rat olfactory bulb. Belluscio and Katz, 2001 Rubin and Katz, 1999

  5. Perceptual similarity of odorants with similar chemical structure: cross-habituation model Presentation of odorants with similar chemical structure Correlation between structural features of odorants and their subjectively perceived odors Cleland et al., 2002

  6. Presentation of odorants with similar chemical structure Representation of odorants in olfactory bulb: similar odorants activate neighboring glomeruli ? Correlation between structural features of odorants and their subjectively perceived odors Aim of our study To examine if disruption of olfactory map affects olfactory discrimination

  7. The tool for investigation of spatial olfactory code: transgenic mice KIR/OIVT with disrupted olfactory map Yu et al., 2004, Neuron

  8. Electrical silencing of olfactory neurons disrupts the olfactory map OB OE

  9. Expression of Kir2.1 and tLacZ in the Olfactory Epithelium Kir 2.1 in situ X-gal Staining X-gal Staining Off Dox On Dox

  10. Restoring Neural Activity Does not Restore the Olfactory Map Control Kir2.1

  11. Questions: • Can KIR/OIVT mice detect odors? • If their ability to detect odors in low concentrations is comparable to control? • Can they discriminate very different odors? • Can they discriminate very similar odors?

  12. Methods: • Subjects: 120 KIR/OIVT mice and their siblings were tested. They were kept on NO DOX diet until PN21, which allowed expression of KIR in olfactory sensory neurons during development and leaded to disrupted olfactory map. After PN21 they were fed with DOX diet, which restored neuronal activity in sensory olfactory neurons, but did not restore map. • Odors: Aliphatic acids, aldehydes, and terpenoids were dissolved in mineral oil to concentrations 10E-6 – 10E-2. • Behavioral paradigm: Spontaneous exploration of odorants was detected by automatic registration system.

  13. Methods of detection of exploratory behavior Last century Last decade Yesterday Manual recording with Videotracking of Videotracking Stopwatch center of animal of marked head of animal Tomorrow Videotracking of nose, tail and center of animal via special software Today Access to an object of exploration controlled by breaking a IR beams situated underneath of holeboard

  14. Spontaneous exploration of odors and olfactory cross-habituation in holeboard Subjects: Mice about 3-6 months old, females and males, KIR/OIVT and their wt littermates. Testing box: 38.5 x 38.5 cm x 60 cm (height), with 16 holes (d=2.5cm) holeboard. Each hole consists of vial for odorants: volume 4 ml, d=1.6 cm, height = 2.5 cm. Distance between surface of holeboard and vial is about 3 cm. Testing protocol: 3-25 sessions 3 min each (ITI=20 min) with possibility to explore vial with odorant, dissolved in mineral oil or control vial with mineral oil.

  15. Detection of aliphatic acids Odor exploration C2 – acetic acid C3 – propionic acid C4 – butyric acid C5 – valeric acid C6 – hexanoic acid C7 – heptanoic acid C8 – octanoic acid C9 – nonanoic acid Locomotor activity General exploratory activity

  16. Detection threshold is comparable between KIR/OIVT and control Odor exploration Locomotor activity General exploratory activity

  17. Discrimination between very different odors: butyric acid and octanal Odor discrimination Butyric acid Octanal Butyric acid Octanal General exploratory activity

  18. Discrimination between very similar odors: enantiomers +carvone and -carvone Linster et al., 2001

  19. Conclusions • Mice with disrupted olfactory map can detect some aliphatic acids, aldehydes and terpenoids. • Their detection threshold for butyric acid is similar to control animals. • Discrimination of very different odorants is spared in KIR/OIVT mice. • Discrimination of very similar odorants is impaired in KIR/OIVT mice. KIR/OIVT mice can be used for probing of functional meaning of spatial olfactory code.

  20. Outlook • Behavioral experiments: To investigate spontaneous exploration of different classes of odorants: alcohols, esters, aldehydes, ketones. To investigate the reason for general hyperactivity and specific increase in reaction to odors of KIR/OIVT mice. We suggest, that it could be result of compensation in response to olfactory deprivation during PN1-PN21, when transgene is ON. To verify this hypothesis, we suggest to investigate a control group of animals without transgene, but olfactory deprived at PN1-PN21. Investigation of KIR/OIVT mice on NO DOX diet, that is with KIR ON, (with diminished neuronal excitability in OSN): can they detect or discriminate odors? Identification of new pairs of similar odorants with different level of similarity, which are perceived as different by control animals, but not by KIR/OIVT. • Evaluation of behavioral discrimination abilities in KIR/OIVT mice should be compared with neuronal activation in olfactory bulb in response to odors for individual animals (i.e. intrinsic optical imaging) • Investigation of receptive fields (tuning) of mitral cells of KIR/OIVT mice by means of electrophysiological methods, i.e. extracellular recordings (Dr.Qiang Qiu).

  21. Acknowledgement Mentor: Ron Yu Construction of holeboard Dmitri Vyssotski Rory Fender Genotyping Limei Ma Evan Gillespie Peniel Zelalem Administrative assistance Nancy Lane Laboratory Animal Services Heather Marshall Les Choromanski Kim Cavanaugh Courtnie Bartley Mike Boyer Bioinformatics Earl Glynn Gaye Hattem Dongxiao Zhu EH&S Tonyea Inglis Shannon Scott Library Judy Zimmerman Rose Owens Sherry Lockwood

  22. Thank you for your attention!

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