GM1 ganglioside restores abnormal responses to acute thermal and mechanical stimuli in aged rats.

We investigated the effect of aging on the responses to thermal and mechanical stimuli in rats. Young (3-5 months old) and aged (22-24 months old) male Sprague-Dawley rats were tested in the hot plate, high- and low-intensity radiant heat tail flick, and von Frey hair assays. Compared to young rats, aged rats displayed longer latencies in the hot plate and the high-intensity tail flick assays (hypoalgesia), but there was no difference in the low-intensity tail flick assay. In addition, aged rats had decreased thresholds to mechanical stimuli produced by von Frey hairs compared with young rats (mechanical allodynia). Administration of GM1 ganglioside, 30 mg/kg, i.p., once daily for 30 days, to aged rats partially restored the responses in the hot plate and von Frey hair assays. GM1 had no effect on the altered responses in the tail flick test in aged rats, and in general, had no effect on any sensory modality tested in young rats.