Amygdalar tissue transplants improve recovery of nociceptive behaviour in rats

Purpose: Amygdala plays a very important role in the mediation of emotional and affective components of pain. Bilateral amygdalectomy increases the th reshold for vocalization, a measure of emotional reactivity, without any ch ange in the tail flick latency. The present work was designed to study the recovery of emotional nociceptive behaviour following neural tissue transpl antation in lesioned rats. Methods: In a group of adult wistar rats lesions of the central nucleus of amygdala (CeA) were produced electrolytically. In a separate group of rat's amygdalar tissue was transplanted at the lesioned site 2 days thereafter. The vocalization tests, viz. simple vocalization (SV) and vocalization afte r discharge (VA), which were used to study the emotional nociceptive behavi our were carried out both before and after producing lesion/transplant. Results: Bilateral CeA lesions increased the thresholds for SV and VA signi ficantly (p < 0.001), indicating analgesia. Following amygdalar tissue tran splantation a significant decrease (p < 0.05) in the thresholds were observ ed when compared with the lesioned group, although when compared with the b asal data it showed an increase (p < 0.05). Conclusions: The results indica te a partial recovery of the vocalization response following amygdalar tiss ue transplantation.