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Description
Flashcards by Pascale Bockelmann, updated more than 1 year ago
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Created by Pascale Bockelmann
almost 8 years ago
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| Question | Answer |
| Prairie Voles | Rodents have OXT receptors in NAc compared to Voles |
| Do mice find social interactions rewarding | CPP measures rewarding properties of experience CPP: baseline test, conditioning, place preference conclusion: OXT receptor activity (somewhere in the brain) necessary for 'social reward' learning |
| Microdialysis Probe | proves: OXT receptors present in NAc |
| Is OXT released in the NAc? | method #1: a) take sample from NAc b) use mass spec to determine if OXT peptide is located in NAc problem = could detect OTX in axons JUST passing through NAc conclusion = presence of OXT peptide in NAc does NOT prove it was released in NAc |
| Is OXT localized in LDCV in axon terminals of NAc | potential method for solving: immunohistochemistry + microscopy |
| Is OXT released in NAc? | a) identify all neurones in the entire brain that form synapses in the NAc (some located in hypothalamus) b) prove some of the hypothalamus neurons that project to NAc contain OXT NOTE: some of the hypothalamic neurons that project to the NAc DON'T contain OXT |
| How to label neurones that project to the NAc? | Viral Mediated Gene Delivery (gene therapy) a) make virus replication deficient (remove DNA) OR add DNA to a virus b) modified virus infects cells it comes into contact with (AAV = soma & RvB= axon terminals) c) once virus DNA enters nucleus cell produces foreign protein d) fluorescent cells identify infected cells |
| What neurones in the brain innervate the NAc? | Paraventricular nucleus of hypothalamus projects to NAc |
| Do PVN neurones produce OXT? | immunohistochemistry used to label OXT containing neurones |
| immunohistochemisty | a) immune system of animals contains antibodies b) antibodies bind to small A.A. that are forgein to the body (a.k.a. antigens) c) can conjugate antibody to green fluorescent protein conclusion: to identify where OXT is, was brain slice in glowing antibody specific to OXT peptide |
| Making an antibody for a specific Protein | a) synthesize protein you want to label b) attach this protein to a known antigen (elicits large immune response in animal) c) inject animal w. OXT-antigen combo d) wait for animal's immune system to make antibodies that target foreign combo e) draw blood from the animal & purify antibodies that specifically bind to OXT (and not known antigen) f) attach antibody to fluorescent marker d) wash brain slices w. sol. & OXT peptide becomes visible |
| Method | RbV-GFP labels NAc-projecting neurones |
| Which neurones in the NAc have OXT receptors? | sol: OXT receptor reporter mice (could have used immunohistochemistry) |
| Are the OXT receptors located on the soma of cells in NAc required for social reward? (can one remove all OXT receptors from soma located on the NAc)? | conditional requirement: presence elf another protein = cre-recombinase (most common) used virus to drive 'cre' expression in cells whose soma is located in NAc |
| Are the OXT receptors located on the soma of cells in NAc required for social reward? | a) cre identifies pairs of Lox P b) cuts out the portion of DNA that Lox P flanks c) any cell that expresses cre protein will have recombination event occur |
| Transgenic vs. Knock in/Knock out mouse | transgenic mice = OXT receptor reporter mouse Transgenic mice = extra DNA added to them Transgenic = GFP reporter mice & cell type specific cre-expression mice |
| knock in/ knock out mice | a) harder to make b/c DNA is added or removed from specific parts of animals genome (a.k.a. genome changed in a targeted manner) i) knock-out mice = targeted deletion of a specific gene ii) knock-in have LoxP added to specific places (a.k.a. conditional knock-out mice) in presence of cre DNA b/w LoxP will be deleted |
| OXT receptor expression in NAc cells isn't required for social reward | AAV (adeno-associated virus) only infect cell bodies, is used to drive expression of 'cre' & GFP in NAc neurones of knock in (condition OXT receptor knock out mice) |
| Brain Slice Electrophysiology | measures voltage change, or electric current |
| Adding OXT to NAc doesn't change excitability of projection neurones v. much, but it reduces f. of glutamate input | - maybe glutamategeric axon terminals located in the NAc express OXT receptors? a) NT receptors (found on axon terminals) can alter probability of vesicle release in response to action potential |
| probability of NT release in response to action potential is mediated by diff. things | a) pre-synaptic calcium levels b) number of readily releasable pool of vesicles c) number of vesicles in the reserve pool conclusion = each can be altered by g-protein receptor signalling cascades in axon terminal |
| long term changes in synaptic strength can be b/c of factors influences in the pre synapse | lk |
| Do any neurones that project to the NAc from anywhere express OXT receptors | OXT receptor expression in cells that innervate the NAc is required for social reward a) RbV used to drive expression of cre (& GFP) in all neurones that project to NAc |
| Which projection to the NAc mediates OXT- dependent social reward? | OXT-receptor expression in dorsal raphe neurons is required for social reward a) AAV only infects cell bodies, used to drive cre ( &GFP) expression in dorsal raphe neurones |
| OXT receptor-expressing cells in dorsal-raphe send serotenergic projections to NAc | serotonin receptor agonist doesn't change excitability of NAc neurones v. much BUT reduces f. of glutamate input ( & subsequent OXT administration has no further effect ) |
| serotonin receptors in NAc required for social reward | OXT doesn't reduce strength of glutamate inputs to the NAc in mice, that have had OXT receptors selectively removed from serotonin neurones |
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