0130 ROLES OF GAD67 IN THE THALAMIC RETICULAR NUCLEUS FOR REGULATING SLEEP SPINDLE GENERATION

Abstract Introduction: Schizophrenic (Sz) patients exhibit a reduction in sleep spindles. The genesis of this spindle deficit is unknown. The GABAergic neurons of the thalamic reticular nucleus (TRN), most of which contain the calcium-binding protein, parvalbumin (PV), are involved in spindle generation. The expression of the GABA synthetic enzyme, glutamate decarboxylase 67 (GAD67), is decreased in cortical PV GABAergic neurons of Sz brains examined postmortem. Thus, one possible explanation for the spindle deficit in Sz is a reduction of GAD67 levels in TRN neurons. Thus, here we selectively deleted GAD67 in the TRN and tested the effect on sleep spindles. Methods: An adeno-associated virus constitutively expressing a Cre recombinase-Green fluorescence protein (GFP) fusion protein (AAV-Cre-GFP) was injected into TRN of homozygous GAD67 floxed mice. The time course of reduction in GAD67 after viral injection was evaluated by immunohistochemistry. Sleep-wake activity (EEG/EMG electrodes) was recorded and sleep-wakefulness states were analyzed according to standard procedures. A custom-designed script (Matlab) was used to detect individual spindles (10-15Hz) during non-REM (NREM) sleep. Results: 1 week after viral injection GAD67 expression in TRN was similar to control (83.3% of control, n=2). However, a pronounced reduction was observed two (11.5%, n=2) and three weeks (6.9%, n=2) after viral injection. In one animal with confirmed unilateral viral transduction in the TRN, NREM spindle density (Spindles/min NREM sleep) during the light period was decreased after 2 weeks of AAV injection (64.3% of control) when compared to a non-transduced control mouse (N=1) or to the same mouse recorded one 1 week after injection. Conclusion: Our results suggest we can successfully delete the GAD67 gene in TRN neurons. Our preliminary data further suggest that reduced GAD67 in TRN neurons leads to a decreased spindle density, similar to that observed in schizophrenia patients. Support (If Any): This work was supported by Veterans Affairs Medical Research Service Awards 5I01BX001356 (RWM), I01BX002774 (RES) and I01BX001404 (RB), a VA Career Development Award 1IK2BX002130 (JMM) and by NIH: R21-NS079866 (RB), RO1-MH039683 (RWM), PO1-HL095491 (RWM), R21 NS093000 (REB). JTM received partial salary compensation and funding from Merck MISP, but has no conflict of interest with this work.