title: Effects of COX inhibition and LPS on formalin induced pain in the infant rat.
abstract: In the adult, immune and neural processes jointly modulate pain. During development, both are in transition and little is known about the role that the immune system plays in pain processing in infants and children. The objective of this study was to determine if inhibition or augmentation of the immune system would alter pain processing in the infant rat, as it does in the adult. In Experiment 1, rat pups aged 3, 10, or 21 (PN3, PN10, and PN21) days of age were pretreated with NS398 (selective cyclooxygenase (COX)-2 inhibitor) or SC560 (selective COX-1 inhibitor) and tested in the intraplantar formalin test to assess effects of COX inhibition on nociception. Neither drug had an effect on the behavioral response at PN3 or PN10 pups but both drugs attenuated nociceptive scores in PN21 pups. cFos expression in the spinal cord likewise was reduced only at PN21. In Experiment 2, pups were injected with lipopolysaccharide (LPS) prior to the formalin test at PN3 or PN21. LPS increased the nociceptive response more robustly at PN21 than at PN3, while increasing cytokine mRNA equally at both ages. The augmentation of pain responding at PN21 was largely during the late stages of the formalin test, as reported in the adult. These data support previous findings demonstrating late maturing immune modulation of nociceptive behaviors.
authors.affiliation: Department of Developmental Neuroscience, New York State Psychiatric Institute, Columbia University College of Physicians and Surgeons, New York.
authors.forename: Deirtra
authors.initials: D
authors.lastname: Hunter
authors.affiliation: Department of Psychology, Mercy College, Dobbs Ferry, New York, 10522.
authors.forename: Christina
authors.initials: C
authors.lastname: Chai
authors.affiliation: Department of Developmental Neuroscience, New York State Psychiatric Institute, Columbia University College of Physicians and Surgeons, New York.|Department of Psychology, Hunter College, City University of New York, New York.
authors.forename: Gordon A
authors.initials: GA
authors.lastname: Barr
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D052246:Cyclooxygenase 2 Inhibitors / Q000494:pharmacology*; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology*; D005557:Formaldehyde / Q000633:toxicity*; D008070:Lipopolysaccharides / Q000494:pharmacology*; D009578:Nitrobenzenes / Q000494:pharmacology*; D059225:Nociception / Q000502:physiology; D010146:Pain / Q000139:chemically induced / Q000188:drug therapy / Q000201:enzymology*; D010147:Pain Measurement / Q000379:methods; D011720:Pyrazoles / Q000494:pharmacology; D020318:Rats, Long-Evans; D013116:Spinal Cord / Q000187:drug effects*; D013449:Sulfonamides / Q000494:pharmacology*
chemical_list: D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors; D008070:Lipopolysaccharides; D009578:Nitrobenzenes; D011720:Pyrazoles; C115461:SC 560; D013449:Sulfonamides; C080955:N-(2-cyclohexyloxy-4-nitrophenyl)methanesulfonamide; D005557:Formaldehyde
keywords: NS398; SC560; immune; ontogeny; pain