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 threshold for vocalization, a measure of emotional reactivity, without any change in the tail flick latency. The present work was designed to study the recovery of emotional nociceptive behaviour following neural tissue transplantation 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 after discharge (VA), which were used to study the emotional nociceptive behaviour were carried out both before and after pro-ducing lesion/transplant. RESULTS: Bilateral CeA lesions increased the thresholds for SV and VA significantly (p < 0.001), indicating analgesia. Following amygdalar tissue transplantation a significant decrease (p < 0.05) in the thresholds were observed when compared with the lesioned group, although when compared with the basal data it showed an increase (p<0.05). CONCLUSIONS: The results indicate a partial recovery of the vocalization response following amygdalar tissue transplantation.