Neonatal gastric suctioning results in chronic visceral and somatic hyperalgesia: role of corticotropin releasing factor

Gastric suctioning is common in neonatal intensive care units. Studies suggest that gastric suctioning in premature infants may play a role in the development of visceral hyperalgesia. We hypothesized that repeated orogastric suctioning during the neonatal period results in chronic alterations in visceral and somatic sensation through a corticotropin-releasing factor mediated mechanism. Neonatal male Long Evans rats (n = 13) received daily orogastric suctioning for 10 days starting at postnatal day two (P2). Control rats (n = 15) were handled similarly without orogastric suction. A second study group was subjected to a similar protocol, only with pre-emptive administration of a CRF1 receptor antagonist (antalarmin, 20 mg/kg, IP) (n = 8). The control group received vehicle only (n = 8). An additional group was given antalarmin without suctioning (n = 5). After these rats grew to adulthood (PN 60), a visceromotor response to graded colorectal distension was recorded (10-80 mmHg, 30s, 180s inter-stimulus intervals) to assess changes in visceral sensitivity. Paw withdrawal latency to noxious heat applied to the hind paws was measured to assess changes in cutaneous sensitivity. Orogastric suctioning during the neonatal period results in global chronic somatic and visceral hyperalgesia in adult rats. Visceral hyperalgesia is prevented by pre-emptive administration of the CRF1 receptor antagonist, antalarmin.