Ciliary neurotrophic factor (CNTF) is the member of IL-6 cytokine family and expressed in the nervous system. CNTF is 22.9 kDa neurotrophic factor containing 200 residues, which shows multiple effects in vertebrate retinogenesis. Besides, CNTF acts as a promoter that not only accelerates adult neurogenesis but also increases the survival of neuron after injury. On the other hands, reducing number of hippocampal GABAergic interneurons, as well as 5-HT levels and 5-HT1A receptor expression has been found in CNTF knockout female mice, indicating that CNTF may influence affective behavior in females by regulation of neurotransmission.