Effect of intrathecal injection of pertussis toxin on substance P, norepinephrine and serotonin contents in various neural structures of arthritic rats.
The possible influence of spinal receptors coupled to Gi/Go regulatory proteins on chronic pain adaptive processes of neural tissues was investigated in normal and arthritic rats. Pain-suffering animals showed an enhanced immunoreactivity to substance P (ir-SP) in the lumbar spinal cord, pons-medulla oblongata region and thalamus. Norepinephrine (NE) levels were increased in the spinal cord, while serotonin (5-HT) was elevated in both spinal cord and midbrain. The intrathecal injection of 1 micrograms pertussis toxin 6 days before sacrifice of rats produced in these arthritic animals a pronounced reduction of ir-SP in the pons-medulla, midbrain and thalamus, but not in the spinal cord. The level of 5-HT was diminished in dorsal spinal cord and midbrain, whereas NE appeared unchanged. In contrast, the toxin only reduced ir-SP of normal rats in the midbrain, without altering the levels of NE or 5-HT, in all the areas analysed. These results suggest the involvement of certain spinal receptors coupled to Gi/Go transducer proteins in processes leading to the elevation of ir-SP and 5-HT in various neural structures of arthritic rats.
Garzón
J
J
Cajal Institute, C.S.I.C., Madrid, Spain.
Lérida
M
M
Sánchez-Blázquez
P
P
D000818:Animals; D001169:Arthritis, Experimental / Q000378:metabolism*; D001921:Brain / Q000187:drug effects* / Q000378:metabolism; D005620:Freund's Adjuvant; D006897:Hydroxyindoleacetic Acid / Q000378:metabolism; D007278:Injections, Spinal; D008297:Male; D009619:Nociceptors / Q000187:drug effects / Q000502:physiology; D009638:Norepinephrine / Q000378:metabolism*; D010146:Pain / Q000188:drug therapy*; D037342:Pertussis Toxin; D011149:Pons / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D012701:Serotonin / Q000378:metabolism*; D013116:Spinal Cord / Q000187:drug effects* / Q000378:metabolism; D013373:Substance P / Q000378:metabolism*; D013788:Thalamus / Q000187:drug effects / Q000378:metabolism; D010566:Virulence Factors, Bordetella / Q000008:administration & dosage / Q000494:pharmacology*
D010566:Virulence Factors, Bordetella; D012701:Serotonin; D013373:Substance P; D006897:Hydroxyindoleacetic Acid; D005620:Freund's Adjuvant; D037342:Pertussis Toxin; D009638:Norepinephrine