The effects of ritalin on the both attentional set shifting and levels of neurotransmitters and their metabolites in the mPFC in rat as a model of attention deficit hyperactivity disorder

Abstract

Objective To evaluate the enhancement effects of ritalin enhancement of attentional set shifting and motor activity by assessing ability of attentional set shifting in juvenile spontaneously hypertensive rats (SHRs)as an animal model of attention deficit and hyperactivity disorder.Methods Sixteen male 4 week-old SHRs were randomly divided into titalin(SR)and saline(SN),control groups(WN)respectively.The number of trails were recorded as the sign of the ability of attentional set shifting.Results The number of trails to reach the criterion of six consecutive was significantly more in the SN group than those of WN group in SD,CD,CDR,IDS,EDS(P＜0.05,P＜0.01).The same was observed in the SN group than in the ritalin-treated group(SR)in all stages except IDSR(P＜0.05,P＜0.01).Ventral subdivisions of mPFC:(1)At the base line,SN((504.142±100.96)ng·g~(-1))group have exhibited a higher NE((354.42±125.38)ng·g~(-1),P=0.001)level,MHPG/DOPAC ratio,a lower utilization ratio(MHPG/NE=3.28±1.11,DOPAC/DA=0.93±0.31)and a lower MHPG level((1560.04±159.69)ng·g~(-1))when compared with the WN subgroup((1709.95±322.29)ng·g~(-1),P=0.000).(2)The ritalin treatment in SHRs decreased MHPG/DOPAC ratio and also increased the utilization ratio(MHPG/NE:1.95±0.37,3.28±1.11,P=0.000;DOPAC/DA:0.31±0.15,0.93±0.31,P=0.000),and MHPG,DOPAC level when compared with the SN group(P＜0.05～P＜0.01).Conclusions(1)The juvenile SHRs have the disability of attentional set shifting,ritalin has shown effect to improve the ability of attentional set shifting in SHRs.(2)Decreased utilization ratios(DOPAC/DA,MHPG/NE)were found in in the ventral subdivision of mPFC in the SHRs while a relative unbalance between hypodopaminergic and hypemoradrenergic activity was also noted.(3)Effects of ritalin has been observed in enhancement of cognitive flexibility by way of increasing the utilization ratios(DOPAC/DA,MHPG/NE)and hence the relative unbalance hypodopaminergic and hypemoradrenergic activity is improved. Key words: Attentional set shifting; Ritalin; mPFC; Neurotransmitter; Coularray detection