1. Astrocyte-Derived Adenosine and A1 Receptor Activity Contribute to Sleep Loss-Induced Deficits in Hippocampal Synaptic Plasticity and Memory in Mice Mohsan Ali

2. Background Sleep deprivation – Sleep loss - Cognitive deficits and function SD increases extracellular adenosine levels in the forebrain and cortex. (Porkka-Heiskanen et al., 1997) Astrocytes release ATP - ATP  Adenosine

3. Sleep Classified into rapid eye movement (REM) and non- rapid eye movement (NREM) stages. REM is characterized by high frequency, low amplitude. NREM is characterized by low frequency, high amplitude

4. Sleep and Memory Synaptic scaling hypothesis suggests that net nerve impulse increase during waking experience.(Liu et al., 2010) Memory trace reactivation hypothesis suggests that memory during wakefulness replays itself during sleep. (Lee and Wilson, 2002)

6. Astrocytes Modulate synaptic activity through ATP directly through P 2 receptors. Controlled through increased Ca 2+ concentration Specifically control slow oscillations during NREM

7. Slow Oscillation Up state – is when action potential firing occurs - Generated by synaptic inputs Down State – characterized by absence of synaptic inputs; membrane resting potential Can be generated in cortical slices

9. Adenosine regulation Derived from many sources in the nervous system ATP is released in the extracellular and then hydrolyzed Adenosine can be released through a direct pathway

10. Adenosine

11. dnSNARE mice SNARE proteins mediate exocytosis of cellular transport vesicles. dnSNARE mice can not carry out exocytosis Astrocytic expression of dnSNARE significantly reduces extracellular adenosine.

13. A1R receptor Adenosine binds to the A1R receptor, which causes inhibition of synaptic transmission. Antagonists (CPT or DPCPX) bind to A1R receptor and enhance synaptic transmission. At least four different adenosine receptors: A1R, A2AR, A2BR, and A3R

14. Slow Oscillation During SD, sleep homeostat increases the drive to sleep - Sleep pressure Sleep pressure is a measure by increased slow wave activity dnSNARE mice reduce the slow oscillation power

16. Purpose To demonstrate that astrocyte-derived adenosine and the adenosine receptor (A1R) play an important role in synaptic plasticity and memory deficits induced by SD. - Whether memory in the object recognition task is affected by SD.

17. Materials and Methods dnSNARE mice were obtained by crossing two mouse lines. Lights were maintained on a 12h light/dark cycle WT and dnSNARE confirmed by PCR

19. Surgical Procedure Brain cannula was placed at the left lateral ventricle. Mini-osmotic pump was implanted between shoulder blades. Coronal sections stained with cresyl violet.

21. Electrophysiology Hippocampal slice preparation with ACSF Electrode placed at the stratum radiatum to elicit action potentials EPSPs recordings were made using ACSF-filled glass microelectrode

22. Spatial Object Recognition Task Conducted in a gray rectangular box (40 X 30 X 30 cm) - polyvinyl chloride plastic 6 minutes – removed After 3 min, placed in box – two different objects for three cons. 6 minutes Testing session

23. Data analysis ANOVA was performed on all experiments > SPSS software - Linear regression slope Comparison was made using t-test

24. Results dnSNARE expression: - (-Dox) dnSNARE and EGFP are coexpressed - (+Dox) dnSNARE and EGFP are not expressed

30. Take Home Message… Astrocyte modulate sleep through adenosine. dnSNARE expressed in astrocyte reduces the power of slow oscillation. SD causes increase in adenosine through astrocyte SD impairs L-LTP in WT but not in dnSNARE. Astrocytes modulate synaptic activity and memory through adenosine