The Changes Of Learning And Memory And Expression Of BDNF In Spinal Dorsal Horn, Hippocampus CA1 Area In Visceral Pain Hypersensitive Immature Rats

Objective Establishing visceral pain hypersensitive model with neonatal maternal separation, to explore the effect of BDNF on the formation of visceral hypersensivity in immature rats.Methods 32 newborn SD rats were divided into four groups by 2 x 2 factorial design,8 in each group: M1C1 group, M1C0 group, M0C1 group and M0C0 group. M1C1 group was given with neonatal maternal separation(NMS) to establish visceral pain hypersensitive model and accepted colorectal distension(CRD) stimulation at the age of 50 days. M1C0 group was given with NMS as M1C1 group but didn’t accept CRD stimulation at the age of 50 days. M0C1 group wasn’t given with NMS but accepted CRD stimulation at the age of 50 days. M0C0 group neither be given with NMS nor accepted CRD stimulation at the age of 50 days. M0C0 group and M1C0 group were sacrificed with M1C1 group and M0C1 group the next day after accepting CRD stimulation, then collecting the L6 ~ S2 spinal cord and detecting the expression of BDNF in spinal dorsal horn by SABC immunohistochemical method.SPSS 18.0 software for Windows was used in all statistical tests. The value of α=0.05 was considered significant.Result With the CRD pressure increased, the amplitudes of spike of external oblique muscle of abdomen(EOMA) increased too. When the CRD pressures were 15 mm Hg、30mm Hg and 45 mm Hg, the spikes of EOMA were higher in M1C1 group than M0C1 group’ rats significantly(P<0.05). But when pressures were 60 mm Hg, 75 mm Hg, the differences were no statistical significance(P>0.05).The percentage(IHS) of spinal dorsal horn BDNF positive cells number in M1C1 group, M1C0 group, M0C1 group and M0C0 group were 32.25%(5.79), 31.18%(5.21), 32.25%(5.64), 24.50%(4.64); the analysis of factorial variance indicated that :NMS can increase the percentage(IHS) of spinal dorsal horn BDNF positive cells number, but a single CRD make no difference to it, there were no interaction between NMS and a single CRD stimulation.Conclusion NMS can establish visceral pain hypersensitive model, the reason for this may be associated with excessive expression of spinal cord dorsal horn BDNF.Objective Establishing visceral pain hypersensitive model with neonatal maternal separation, to explore The changes of learning ability and memory and expression of the hippocampus CA1 area BDNF in visceral pain hypersensitive immature ratsMethods 32 newborn SD rats were divided into 2 groups, 16 in each group: M1 group and M0 group. M1 group was given with neonatal maternal separation(NMS) to establish visceral pain hypersensitive model, M0 group was given with NMS. At the age of 35 days, both the two groups were accepted Morris water maze test. At the age of 50 days, these rats were divided into 4 groups according to whether to accept CRD stimulation, 8 in each group. They were M1C1 group, M1C0 group, M0C1 group and M0C0 group. M1C1 group was given with NMS and accepted CRD stimulation at the age of 50 days. M1C0 group was given with NMS but didn’t accept CRD stimulation at the age of 50 days. M0C1 group wasn’t given with NMS but accepted CRD stimulation at the age of 50 days. M0C0 group neither was given with NMS nor accepted CRD stimulation at the age of 50 days. M0C0 group and M1C0 group were sacrificed with M1C1 group and M0C1 group the next day after accepting CRD stimulation, then collecting the hippocampus and detecting the expression of BDNF in hippocampus CA1 area by SABC immunohistochemical method.SPSS 18.0 software for Windows was used in all statistical tests. The value of α=0.05 was considered significant.Result With the times of training increased, the escape latency and total distances decreased in contrast. In the same day, the escape latency is no difference between M1 group and M0 group in the place navigation experiment(p>0.05). In spatial probe, the number of the rats cross the location previously containing the platform、the ratio of the time rats spent in the quadrant previously containing the platform to all time and the ratio of the distances rats spent in the quadrant previously containing the platform to all distances in these two group were:M0 2.29, 25.60%, 25.60%; M1 3.53, 29.30%, 30.14%; The difference was statistically significant(p<0.05).The percentage(IHS) of hippocampus CA1 area BDNF positive cells number in M1C1 group、M1C0 group、M0C1 group and M0C0 group were 26.47%(5.50), 40.41%(3.58), 33.86%(5.57), 42.25%(7.28); the analysis of factorial variance indicated that :NMS can increase the percentage(IHS) of hippocampus CA1 area BDNF positive cells number, but a single CRD make no difference to it, there were no interaction between NMS and a single CRD stimulation.Conclusion NMS can lead to visceral pain hypersensitity and deficiency of learning ability and memory in immature rats, which is characterized by lower Morris water maze experiment performance and hippocampus CA1 area BDFN expression.