Reversal of hyperalgesia by transplantation in lateral hypothalamic lesioned rats.

Lateral hypothalamus (LHA) plays a very important role in the modulation of nociceptive behaviour. The stimulation of LHA is known to produce analgesia of both tonic and phasic pain. The present study reports hyperalgesia induced by lateral hypothalamic lesions and the effect of fetal (gestation day 16) hypothalamic transplant on the nociceptive response to phasic thermal noxious stimulation [tail flick latency (TFL)] in LHA lesioned rats. The TFL decreased significantly (12.91 +/- 3.91 sec to 10.51+/- 1.23 sec) following LHA lesion. However, after transplantation, the TFL did not change. This is the first report of a hypothalamic transplant inducing recovery of a nociceptive response.