I. Introduction 1 II. Materials and Methods 7 III. Results 20 3.1 Deletion of PLCη1 in lateral habenula astrocyte with adeno-associated viral vector 20 3.2 PLCη1 in lateral habenula effect on depressive-like behavior 23 3.3 PLCη1 in lateral habenula did not effect the motor function and anxiety-like behavior 26 3.4 PLCη1 in lateral habenula did not alter working and fear memory 30 3.5 Deletion of astrocytic PLCη1disrupts tonic glutamate current in the LHb while sparing tonic GABA current 33 3.6 Impairment of extra synaptic long-term depression (LTD) in the deletion mice of astrocytic PLCη1 36 3.7 Astrocytic PLCη1 in lateral habenula disrupt synaptic function and regulate mood state 40 IV. Discussion 42 V. References 45