Modulation of expression of fear by oxytocin signaling in the central amygdala: From reduction of fear to regulation of defensive behavior style

Many studies in preclinical animal models have described fear-reducing effects of the neuropeptide oxytocin in the central nucleus of the amygdala. However, recent studies have refined the role of oxytocin in the central amygdala, which may extend to the selection of an active defensive coping style in the face of immediate threat, and also fear-enhancing effects have been reported. On top of this, oxytocin enables the discrimination of unfamiliar conspecifics on the basis of their emotional state, which could allow for the selection of an appropriate coping style. This is in line with many observations that support the hypothesis that the precise outcome of oxytocin signaling in the central amygdala or other brain regions depends on the emotional or physiological state of an animal. In this review, we highlight a number of studies to exemplify the diverse effects oxytocin exerts on fear in the central amygdala of rodents. These are discussed in the context of the organization of the neural network within the central amygdala and in relation to the oxytocin-synthesizing neurons in the hypothalamus.