1 / 73

Anxiety – behavioural state arising in anticipation of potential threat

Anxiety – behavioural state arising in anticipation of potential threat Protective role by preparing an organism for potential danger Becomes pathological when exaggerated or uncontrollable Anxiety disorders - abundant and costly

kaiya
Télécharger la présentation

Anxiety – behavioural state arising in anticipation of potential threat

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Anxiety – behavioural state arising in anticipation of potential threat • Protective role by preparing an organism for potential danger • Becomes pathological when exaggerated or uncontrollable • Anxiety disorders - abundant and costly • 20% of the general population suffer from at least one form of anxiety disorder at some point of their life • Financial cost of more than 65 billion dollars in Canada alone

  2. Neural substrates underlying anxiety 1. A neural substrate defined by gene expression pattern in the developing embryo 2. A neural substrate defined by connectivity in the adult brain

  3. Neural substrates underlying anxiety • 1. A neural substrate defined by gene expression pattern in the developing embryo • Genetically distinct subset of serotonergic neurons • 2. A neural substrate defined by connectivity in the adult brain - Hippocampus to amygdala connection

  4. Serotonin (5HT)-producing neurons 9 clusters (nuclei) B1-B9 BRAINSTEM

  5. Autonomic body physiologymodulation of breathing, body temperature blood pressure heart rate • learning and memory • sensorimotor gating • modulation of mood states Serotonin (5HT)-producing neurons 9 clusters (nuclei) B1-B9 BRAINSTEM

  6. Serotonergic neurons are implicated in a range of clinical disorders: • Autonomic body physiologymodulation of breathing, body temperature blood pressure heart rate • learning and memory • sensorimotor gating • modulation of mood states • Sudden infant death syndrome • Fetal alcohol syndrome • Autism • Anxiety • Depression • Addiction and Compulsive behaviors Serotonin (5HT)-producing neurons 9 clusters (nuclei) B1-B9 BRAINSTEM

  7. Serotonergic neurons have different functional properties • different Anatomical locations • different Projection patterns • different Cell morphologies • different Physiological properties Message:there are many subtypes of serotonergic neurons

  8. Which serotonin neurons underlie which behaviors and physiological processes? • breathing • heart rate • blood pressure • learning and memory • sensorimotor gating • anxiety • aggression ?

  9. Defining serotonergic neurons by gene expression pattern during early development • breathing • heart rate • blood pressure • learning and memory • sensorimotor gating • anxiety • aggression ?

  10. Serotonergic neuron progenitors are located in embryonic hindbrain r1 embryonic hindbrain Serotonergic progenitors Serotonergic progenitors r4 r7 dorsal view

  11. Embryonic hindbrain is composed of morphologically distinct structures called rhombomeres r1 r2 r3 embryonic hindbrain Serotonergic progenitors r4 r5 r6 r7 dorsal view

  12. Rhombomeres are molecularly distinct structures expressing different sets of genes r1 r2 r3 embryonic hindbrain rhombomeres r4 Serotonergic progenitors r5 r6 r7 Ebk Elf-2 Elk-L Sek-4 Sek-3 Sek-2 Sek-1 Elk-L3 Hoxb3 Hoxa-4 Hoxb-2 Hoxa-2 Hoxb-4 Hoxd-4 Hoxa-3 Hoxb-1 Hoxa-1 Hoxd-3 Kreisler Krox-20 Adapted from Lumsden and Krumlauf, 1996

  13. Rhombomeres are molecularly distinct structures expressing different sets of genes Message: serotonergic neuron progenitors in different rhombomeres have different gene expression pattern embryonic hindbrain Serotonergic progenitors dorsal view

  14. embryonic hindbrain Serotonergic progenitors Question: How the embryonic gene expression patterns are related to serotonergic neuron function? dorsal view

  15. Dual recombinase-mediated gene activation loxP loxP FRT FRT effector BAP OFF

  16. Dual recombinase-mediated gene activation loxP loxP FRT FRT effector BAP OFF excision Cre FRT FRT BAP effector OFF

  17. Dual recombinase-mediated gene activation loxP loxP FRT FRT effector BAP OFF excision Flp loxP loxP OFF effector BAP

  18. Dual recombinase-mediated gene activation loxP loxP FRT FRT effector BAP OFF Cre Flp effector ON BAP

  19. Dual recombinase-mediated gene activation loxP loxP FRT FRT effector BAP OFF GeneB::Flp GeneA::Cre effector ON BAP cre Flp

  20. Dual recombinase-mediated gene activation loxP loxP FRT FRT effector BAP OFF GeneB::Flp GeneA::Cre effector ON BAP Effector ON

  21. GFP GFP Pet1-Flpe ON Serotonergic-specific Flpe FRT FRT loxP loxP rosa26 CAG promoter F F P OFF P Flpe Cre rosa26 ON GFP-TOX CAG promoter F P r1 r2 r3 r4 Rhombomere-specific Cre lines r5 r6 r7

  22. GFP GFP Pet1-Flpe ON Serotonergic-specific Flpe FRT FRT loxP loxP rosa26 CAG promoter F F P OFF P Flpe Cre rosa26 ON GFP-TOX CAG promoter F P r1 r2 r3 r4 r5 Rhombomere-specific Cre lines r6 r7

  23. Genetic fate map of serotonergic neurons Jensen et al, Nature Neuroscience 2008

  24. contributions from a single rhombomere Genetic fate map of serotonergic neurons Jensen et al, Nature Neuroscience 2008

  25. contributions from a single rhombomere contributions frommultiple rhombomeres contributions frommultiple rhombomeres Genetic fate map of serotonergic neurons Jensen et al, Nature Neuroscience 2008

  26. contributions from a single rhombomere contributions frommultiple rhombomeres contributions frommultiple rhombomeres Message #1: Genetic Fate map = Classical, Anatomical Map

  27. contributions from a single rhombomere contributions frommultiple rhombomeres contributions frommultiple rhombomeres Message #1: Genetic Fate map = Classical, Anatomical Map Message #2: provide framework to study the function of genetically defined serotonergic neuron subtypes

  28. Question: How the embryonic gene expression patterns are related to serotonergic neuron function?

  29. GOAL - Silence individual serotonergic neuron subtypes to determine their function loxP loxP FRT FRT GFP-TOX BAP

  30. GOAL - Silence individual serotonergic neuron subtypes to determine their function loxP loxP FRT FRT GFP-TOX BAP Tetanus toxin light chain : blocks neurotransmitter release

  31. FIRST - silence all serotonergic neurons to reveal the full extent of attainable phenotypes loxP loxP FRT FRT GFP-TOX BAP

  32. Assayed a set of 3 behaviors known to be modulated by serotonin (5-HT): contextual learning anxiety-related behaviors sensorimotor gating • contextual fear conditioning • open field • prepulse inhibition of acoustic startle • elevated zero maze • light-dark exploration test Collaborator Melloni Cook Tennessee Mouse Genome Consortium Neuromutagenesis Project

  33. 24hrs assay fear-induced freezing repeat x3 at 2.5 min intervals Contextual Fear Conditioning Paradigm Can they learn to associate an aversive stimulus to a particular cage context?

  34. 24hrs assay fear-induced freezing repeat x3 at 2.5 min intervals Contextual Fear Conditioning Paradigm enhanced fear induced freezing behavior p<.044

  35. 24hrs assay fear-induced freezing repeat x3 at 2.5 min intervals “silenced” mice show enhanced contextual learning and memory No difference No difference Activity in the altered context enhanced fear induced freezing behavior p<.044 Control triple

  36. innate fear of open areas vs. desire to explore novel environments Mice with higher level of anxiety-related behavior spend more time here. Elevated zero maze (advancement over Plus maze) Light-dark exploration test Open field test 3 tests of anxiety-related behaviors

  37. Light-dark exploration test Open field test Elevated zero maze * *p< 0.03 n=34 n=32 A 2-factor (genotype x sex) multivariate analysis of variance (MANOVA) was used. F(1,62)=4.81, p<.032

  38. “silenced” mice (ePet1::Flpe, hßact::Cre, RC::PFtox) contextual learning anxiety-related behaviors sensorimotor gating

  39. 120 dB sensorimotor gating: a neurological gating process that prevents distracting sensory inputs from generating unnecessary motor outputs regulation is disrupted in Schizophrenia and Huntington disease operationally measured by inhibition of the acoustic startle response after a leading (prepulse) stimulus % inhibition pulse Startle response : indication of sensorimotor gating 85 dB Stimulus intensity Stimulus intensity prepulse TIME TIME

  40. control “silenced” - Pet1Flpe, hßact-cre, RC::PFtox “Silenced” mice exhibited less of a startle in presence of a prepulse “Silenced” mice show enhanced sensorimotor gating. Prepulse Inhibition (PPI) test P<.007 P<.023 Mean percentage Inhibition of Startle Response background white noise

  41. “silenced” all serotonergic neurons contextual learning anxiety-related behaviors sensorimotor gating

  42. Do serotonergic neurons with different embryonic origins serve different functions? “silenced” all serotonergic neurons contextual learning anxiety-related behaviors sensorimotor gating

  43. What if we “silence” just the r1-derived 5-HT neurons? contextual learning anxiety-related behaviors sensorimotor gating TOX in All 5-HT neurons ? ? ? r1-derived 5-HT neurons

  44. contextual learning anxiety-related behaviors sensorimotor gating silence all 5-HT neurons r1-derived

  45. contextual learning anxiety-related behaviors sensorimotor gating silence all 5-HT neurons r1-derived no difference no difference

  46. R1-derived 5-HT neurons may modulate anxiety-related behaviors contextual learning anxiety-related behaviors sensorimotor gating silence all 5-HT neurons r1-derived no difference no difference Anxiety-related behaviors

  47. Modulated more by r2- and/or r3-derived 5-HT neurons? contextual learning anxiety-related behaviors sensorimotor gating silence all 5-HT neurons r1-derived no difference no difference Anxiety-related behaviors Contextual learning Sensorimotor gating

  48. r2-derived r3-derived r5-derived Modulated more by r2- and/or r3-derived 5-HT neurons? contextual learning anxiety-related behaviors sensorimotor gating silence all 5-HT neurons r1-derived no difference no difference in progress

  49. GOAL - Assigning specific serotonergic neuron subtypes to specific behaviors contextual learning anxiety-related behaviors sensorimotor gating X serotonergic neuron subtype ? ?

  50. Neural substrates underlying anxiety • 1. A neural substrate defined by gene expression pattern in the developing embryo • Genetically distinct subset of serotonergic neurons • 2. A neural substrate defined by connectivity in the adult brain - Hippocampus to amygdala connection

More Related