Effects of lesion or stimulation of pituitary gland and hypothalamic arcuate nucleus on pain modulation in rats

Relationship between pituitary gland and hypothalamic arcuate nucleus (ARC) in the modulation of pain threshold was investigated in Wistar rats with method of focal lesion and stimulation of pituitary gland. Experimental results indicated that electrolytic lesion of the pituitary intermediate and anterior lobes resulted in a decrease of pain threshold and disappearance of the analgesia immediately produced by ARC stimulation. Stimulation of the same area of pituitary gland could induce a delayed analgesia,which could be blocked by ARC lesion.