Effects of repetitive noxious stimuli during neonatal period on pain sensitivity during adulthood in rats / 中华麻醉学杂志

ABSTRACT

Objective To evaluate the effects of repetitive noxious stimuli during the neonatal period on the pain sensitivity during adulthood in rats.Methods Twenty pathogen-free male neonatal SpragueDawley rats,weighing 6.2-6.8 g,were randomly divided into 2 groups (n=10 each) using a random number tablecontrol group (group C) and repetitive noxious stimuli group (group RNS).In RNS group,neonatal rats sequentially received needle pricks into the dorsal surface of 4 paws at 6 h intervals with a 28 G needle per day during the first postnatal week.In group C,the animals received non-painful tactile stimuli with cotton tip rub.At the age of 10 weeks,complete Freund' s adjuvant was injected into the plantar surface of the right hind paw to induce inflammatory pain.Before injection,and at 24 h and 7 days after injection (T0-2),the mechanical and thermal thresholds were measured,and alcohol preference test was performed for assessment of the behavior at T2.Results The mechanical threshold of the right paws was significantly lower at T1.2 than that of the left paws in the two groups.Compared to group C,the mechanical threshold of the left and right paws at T0-2 and thermal threshold of the right paws at T1 were significantly decreased,and alcohol intake was increased in group RNS.Conclusion Repetitive noxious stimuli during the neonatal period can lead to increase in the pain sensitivity during adulthood in rats.