Harmful Effects at Early Age Alter Pain Sensitivity in Adult Female Rats and Its Correction with Buspirone

Abstract

Most studies of the influences of harmful pain and stress during the neonatal period of development on pain sensitivity are performed in males. We report here our studies of inflammatory pain and/or maternal deprivation stress in neonatal female rats on pain sensitivity in adulthood; an attempt was made to correct these changes using the 5-HT1A receptor agonist buspirone. Adult females subjected to early pain showed increased hypoalgesia in the hotplate test, while those subjected to maternal separation stress showed increased hyperalgesia in the formalin test. Pain and subsequent maternal separation had no effect on pain sensitivity in adult females. Chronic administration of buspirone from day 25 to day 39 of life to females subjected to inflammatory pain or maternal separation in the neonatal period normalized pain sensitivity in adults. In female rats, the prepurbertal period was found to be critical for correction of abnormalities in the nociceptive system induced by harmful actions at neonatal age.