Effects of chronic pain on spatial learning ability and expression of neuronal cell adhesion molecule in hippocampus in neonatal rats / 中华麻醉学杂志

ABSTRACT

Objective To investigate the effects of chronic pain on spatial learning ability and the expression of neuronal cell adhesion molecules (NCAM) in hippocampus in neonatal rats.Methods Sixty newborn SD rats of both sexes were randomly divided into pain group ( n = 30) and control group ( n= 30). In pain group complete Freund' s adjuvant (CFA) 20 ?l was injected subcutaneously in the plantar surface of left hindpaw on the 2nd day after birth, whereas in control group normal saline 20 ?l was injected instead of CFA. The animals were weighed on the 3rd, 11th and 22nd day after birth. Ten animals in each group were anesthetized with intraperitoneal pentobarbital and killed on the 11th and 22nd day after birth respectively. The brains were immediately removed for determination of NCAM expression in CA3 and dentate gyms of hippocampus using immuno-histochemical staining technique. Morris water maze test was performed starting from the 21st day after birth for 8 consecutive days to assess the spatial learning ability ( n = 10 in each group) .Results The latent period before finding the hidden-plateform was significantly longer on the 1st and 4th day of the test (22nd and 25th day after birth) in pain group than in control group (P