The Protracted Withdrawal Symptom Variation Of Rats Treated With Chronic Cocaine And It’s Relation With The Expression Of Bmal1 Induced By GSK3β In Hippocampus

Object Protracted withdrawal symptom which include circadian rhythm chaos passive mood and body symptom is a very important factor to cause relapse.We found that protracted symptoms of cocaine dependence rats varied at different times,and when we explored the molecule mechanism of protracted symptom in brain,we found that phosphorylation glycogen synthase kinase 3β(p GSK3β) of rats on condition of normal physiological state had significant circadian rhythm at Ventral tegmental area(VTA),Nucleus accumbense(Nac),Prefrontal cortex(PFC),Suprachiasmatic nucleus(SCN),but the levels and circadian rhythmicity of p GSK3β in the four drug reward brain regions was abnormal after treated cocaine.some research showed,glycogen synthase kinase 3β(GSK3β) may impacted bmal1’s expression indirectly.Our research is To investigate the the role of glycogen synthase kinase 3β(GSK3β)and the bmall1 in the protract withdrawal symptoms and the underlying mechanisms, the alteration of GSK3β and circadian rhythm gene bmal1 in hippocampus(HIP), a key brain area related to drug addiction, of the rats chronically treated by cocaine or saline will be measured. The current study will be helpful to underpin the theoretical basis for developing effective drugs to prevent relapse.Methods In our research,we explored the variation of protracted symptom and the circadian rhythm of GSK3β, p GSK3β and bmal1 m RNA’s expression after cocaine withdrawal 3 days,10 days and 30 days.First of all, rats were adapted in 12h/12 h environment(light on at 8:00,light off at 20:00) for 7 days,and divided into two major groups of saline and cocaine.Rats of group saline were given 1ml/kg saline by intraperitoneal injection for 14days; rats of group cocaine were given i.p.cocaine of 20 mg/kg for 14 days,then withdrawal 3 days,10 days and 30 days,were named as d3,d10 and d30 group respectively. All rats were divided into seven time points, respectively,at ZT0(8:00),ZT4(12:00),ZT8(16:00),ZT12(20:00),ZT16(24:00),ZT20(4:00) and ZT24(8:00).After chronic administration,body weight of rats were measured before and after withdrawal to determine weight gain; the circadian rhythm of activity and depression-like symptoms of rats were tested by open-field and sucrose preference experiment at different times after cocaine withdrawal to oberve the protracted symptoms of chronic cocaine;the circadian rhythm of GSK3β, p GSK3β in Hip were tested by western-blot;the circadian rhythm of bmal1 m RNA in Hip was tested by Realtime-PCR.Results The activity of rats in saline group had significant circadian rhythm, the activation levels of rats at the night was more than that at the day, at(24:00,ZT16) time point the rats activated most fiercely,at the time the ratio of GSK3β/ p GSK3β was largest,and the expression of bmal1 m RNA was lowest;After treated with chronic cocaine,when withdrawal for 3 days,the protracted symptoms included weight gain reduction, depression,lower activity,the activity had circadian rhythm,the activation levels of rats at the day was more than that at the night, at(16:00,ZT8) time point the rats activated most fiercely,at the time the ratio of GSK3β/ p GSK3β was largest,and the expression of bmal1 m RNA was lowest;withdrawal for 10 days,rats showed weight gain reduction, lower depression,the activity had circadian rhythm,the activation levels of rats at the day was more than that at the night, at(12:00,ZT4) time point the rats activated most fiercely,at the time the ratio of GSK3β/ p GSK3β was largest,and the expression of bmal1 m RNA was lowest;withdrawal for 30 days,rats showed the activity, the ratio of GSK3β/ p GSK3β and the expression of bmal1 m RNA had no circadian rhythm.Conclusion Protracted withdrawal symptoms of cocaine dependence rats are differential that dependes on the abstinence timepoint. Circadian rhythm chaos will endure a long time after cocaine withdrawal, which may be one of the main reasons to induce relapse to cocaine reconsumption. Expression of bmall1 in the HIP induced by GSK3β may have an important role in the activity circadian rhythm chaos after cocaine withdrawal.