Electrical stimulation of the dorsolateral periaqueductal gray (dlPAG) has frequently been shown to induce escape and freezing/decreased locomotion responses which mimic panic- and fear-like behaviour. In the present study we tested whether such spontaneous fear-like behaviour could be observed in an open-field test 12 h after dlPAG stimulation. Further, we tested whether this fear-like behaviour could be attenuated by acute or chronic administration of buspirone and escitalopram. Our data demonstrate for the first time that animals showed fear-like behaviour 12 h after dlPAG stimulation, which may possibly reflect panic disorder with anticipatory anxiety/agoraphobic symptoms. Acute and chronic escitalopram, but not buspirone, treatment attenuated the fear-related behaviour. Besides, our data also showed that the stimulation intensities to evoke an escape reaction, a panicogenic response, were significantly higher after chronic buspirone and escitalopram treatment. These results suggest that the fear-like response, which was observed 12 h after dlPAG stimulation, could be considered as a relevant animal model for panic disorder with anticipatory anxiety/agoraphobic symptoms.
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