Numerous recent studies have demonstrated that electrical stimulation of the periaqueductal gray matter (PGM) can result in powerful analgesia to pain of somatic origin. In the present study, we have developed a visceral pain test employing intraperitoneal injection of hypertonic saline which yields a writhing response in the adult rat more reliably than other painproducing substances. With this test we show that writhing as well as the response to radiant heat (tail flick test) are completely inhibited in all animals with PGM electrode placements.
Bibliographical noteFunding Information:
The authors wish to express their gratitude to Dr. S.T. Huprich for his assistancein these experiments. This work was supported by USPHS Grant NS 07628.