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 inthrathecal injection of 1 μg 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. © 1990.
Garzón, J., Lérida, M., & Sánchez-Blázquez, P. (1990). Effect of intrathecal injection of pertussis toxin on substance P, norepinephrine and serotonin contents in various neural structures of arthritic rats. Life Sciences, 47(21), 1915–1923. https://doi.org/10.1016/0024-3205(90)90403-E