| ObjectiveIn this study,we established an autistic rat model that was obtained in the offspring of the female SD rat that received a single intraperitoneal injection of VPA on the 12.5 pregnancy day. Then the behavioral of learning and memory tests and the expression levels of serotonin(5-hydroxy tryptamine, 5-HT) in the hippocampus were performed to study the effect and possible mechanism of eugenol treatment through olfactory pathway in autistic rat.Methods(1) Established an autistic rat model. The autistic group of female SD rats received a single intraperitoneal injection of sodium valproate on the 12.5th pregnant day.Control group was injected with the same amount of physiological saline. The offspring of the autistic group females was marked as the sodium valproate group(VPA group); while the saline group(NS group) marking control group females.The born day was recorded for the first day of postnate(P1). Then the behavioral and development tests were performed in the offspring of the two groups.2)Studied the effect of eugenol by olfactory pathway on learning and memory impairment and possible mechanisms in autism model rats: Selected a successful model of P35 mouse model of autism 20, were randomly divided into model eugenol group(VPA-E, n = 10) and model control group(VPA-C, n = 10), while saline pups as normalcontrol group. VPA-E group of rats were treated with eugenol(the consistence is 1/000) for four weeks, three times a day, every time 30 min,, while the control group distilled water. Morris water maze was measured in each group of rats to record learning and memory ability. The time to find platform( escape latency) and times through the platform( the numbers crossing the platform) were the indicators. Recorded improvement of learning and memory disorders of autism rats after eugenol oil by olfactory pathway; after the end of the behavioral test, rats were killed to obtain brain tissue. Observed the changes levels of 5-HT expression using immunohistochemical staining in the hippocampus.Result(1) Compared with the NS group, VPA group rats showed slow growth and development, the specific performance : the loss weight on P7, P14, P21, P56; lower score of opening eyes on PN13-15; poor direction tend on PN7-10, lower score of swimming performance on PN8, PN12,delayed olfactory discrimination on PN9-11,that these differences were significant(P <0.05); behavioral aspects of VPA group rats showed a reduced number of social behavior with shortened duration of the behavior and the difference was significant(P <0.05); reduced exploratory behavior with increased duration of repeated grooming(P <0.05); Morris water maze test, VPA group rats showed significantly longer escape latency(P <0.05), the reduced number of crossing platform, the difference was significant(P <0.05).(2) The treatment of eugenol oil for 4 weeks, the escape latency of VPA-C group was longer than NS group with fewer numbers of crossing platforms, the difference was statistically significant(P <0.05);the escape latency of VPA-E group rats was shorter than VPA-C group with more numbers of crossing platform(P <0.05),but no significant difference between NS group.(3) Results of immunohistochemistry. Compared with NS group, the content of 5-HT of VPA group in hippocampus were decreased. Also the content of 5-HT between the treatment group and VPA group were different.Conclusion(1) VAP group rats showed growth retardation, reducing the frequency and shortened duration of social behavior, repetitive behavior, reducing exploration activities and disorders of learning and memory, VPA autism model has good validity and good reproducibility.(2) Eugenol oil had an improved effect on learning and memory impairment in rats with autism by the olfactory pathway(3) The possible mechanism of eugenol improving learning and memory impairment of autism rats was related to the increase of the content of 5-HT in Hippocampus.. |
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