Glycine or its receptor antagonist, strychnine, were administered perispinally to investigate their effect on nociceptive responses selicited by activation of various cutaneous receptors. Strychnine produced dose-dependent sensory and motor disturbances; 1 and 5 μg doses were sub-convulsive, eliciting recurrent episodes of coordinated grooming, scratching and biting at the skin, which persisted for approximately 10 minutes post-injection; higher doses (25 and 100 μg) increased the intensity and duration of these effects, and produced convulsive motor seizures. Motor disturbances were not elicited by glycine (5, 25, 100 and 400 μg). Strychnine treated rats, at all doses, vocalized consistently in response to light cutaneous stimulation; a significant proportion of glycine treated rats also vocalized, but were not as sensitive to mild stimulation. Skin hyperalgesia persisted for at least 30 minutes in both strychnine and glycine treated rats. Both strychnine and glycine significantly reduced vocalization thresholds to tail shock. However, no clear effect on tail flick latency was observed following either strychnine or glycine. These results indicate that glycinergic neurons contribute to the tonic regulation of nociceptive input at the spinal cord.
All Science Journal Classification (ASJC) codes
- Biochemistry, Genetics and Molecular Biology(all)
- Pharmacology, Toxicology and Pharmaceutics(all)