Blockade of endocannabinoid system by oxytocin attenuates memory deficits in oxycodone-treated rats.

Oxycodone is a highly prescribed opioid and its abuse has been rampant. Accumulating evidence shows that the cannabinoid CB1 receptor (CB1R) plays a key role in mediating rewarding effects to opioids. However, the downstream signalling of CB1R induced by oxycodone remains unclear. The neuropeptide oxytocin is well known as a potential remedy for drug addiction. Thus, our study aims to explore the mechanism of oxycodone-induced learning and memory deficits underlying the endocannabinoid system (ECS) and the effect of oxytocin. Rats were intraperitoneally injected with oxycodone once a day for eight consecutive day. Novel object recognition, resident-intruder and Morris Water Maze tests were employed to assess the cognitive, social and spatial memory of the rats after oxycodone withdrawal. The (co-)expression of CB1R, cyclin-dependent kinase 5 (Cdk5), regulatory protein p25, tau and phosphorylated tau was measured 1 day after the last behavioural test. The histopathological staining and synaptic density in the hippocampus were observed as well. We found that oxycodone upregulated the expression of p-GSK3ß, co-expression of p-Cdk5 and p25 through CB1R. This finding was accompanied by elevation of pSer396, pSer404 in the tau, and reduction of the number of neurons, dendritic spines and synaptic density in the hippocampus. Furthermore, i.c.v. treatment with oxytocin ameliorates memory deficits in oxycodone-treated rats through inhibition of the ECS. We propose further studies on the clinical use of this neuropeptide, which may potentially cure drug addiction.

Oxytocin prevents cue-induced reinstatement of oxycodone seeking: Involvement of DNA methylation in the hippocampus.

Oxycodone is one of the most commonly used analgesics in the clinic. However, long-term use can contribute to drug dependence. Accumulating evidence of changes in DNA methylation after opioid relapse has provided insight into mechanisms underlying drug-associated memory. The neuropeptide oxytocin is reported to be a potential treatment for addiction. The present study sought to identify changes in global and synaptic gene methylation after cue-induced reinstatement of oxycodone conditioned place preference (CPP) and the effect of oxytocin. We analyzed hippocampal mRNA of synaptic genes and also synaptic density in response to oxycodone CPP. We determined the mRNA levels of DNA methyltransferases (Dnmts) and ten-eleven translocations (Tets), observed global 5-methylcytosine (5-mC) and 5-hydroxymethylcytosine (5-hmC) levels, and measured DNA methylation status of four synaptic genes implicated in learning and memory (Arc, Dlg1, Dlg4, and Syn1). Both synaptic density and the transcription of 15 hippocampal synaptic genes significantly increased following cue-induced reinstatement of oxycodone CPP. Oxycodone relapse was also related to markedly decreased 5-mC levels and decreased transcription of Dnmt1, Dnmt3a, and Dnmt3b; in contrast, 5-hmC levels and the transcription of Tet1 and Tet3 were increased. Oxycodone exposure induced DNA hypomethylation at the exons of the Arc, Dlg1, Dlg4, and Syn1 genes. Intracerebroventricular (ICV) administration of oxytocin (2.5 µg/µl) specifically blocked oxycodone relapse, possibly by inhibition of Arc, Dlg1, Dlg4, and Syn1 hypomethylation in oxycodone-treated rats. Together, these data indicate the occurrence of epigenetic changes in the hippocampus following oxycodone relapse and the potential role of oxytocin in oxycodone addiction.

[Effect of Transcutaneous Acupoint Electrical Stimulation on Propofol Usage in Closed-loop Anes- thesia Delivery System in Pediatric Cardiac Surgery].

Objective To evaluate the effect of transcutaneous acupoint electrical stimulation (TEAS) on propofol usage in closed-loop anesthesia delivery system and pediatric hemodynamics. Methods Sixty children patients undergoing selective tonsillectomy and adenoidectomy surgeries were randomly allocated to the TEAS group (T) and the control group (C) , 30 in each group. Anesthesia maintenance in both groups was performed by propofol closed-loop anesthesia infusion system after induction of anesthesia. Patients in group T were treated with continuous TEAS (2/100 Hz sparsedense wave, 8 - 12 mA) at unilateral Hegu (L14) and Shenmen till the end of surgery. No TEAS was performed to patients in group C. Mean arterial pressure (MAP) and heart rate (HR) were recorded before anesthesia (TO), immediately after intubation ( T1) , 5 min after intubation (T2) , 10 min after intubation (T3) , 15 min after intubation (T4) , the time for intubation (T5) , respectively. The total dose of propofol, times for propofol dose adjustment, average target concentration, cases of patients with extra Fentanyl were recorded during anesthesia maintenance. Bispectral index (BIS) was recorded. Pediatric Anesthesia Emergence Delirium (PAED) scale and Modified Children's Hospital of Eastern Ontario Pain Scale (MCHEOPS) were assessed at T5, 5 min after extubation (T6) , 10 min after extubation (T7) , 15 min after extubation (T8), 30 min after extubation (T9) , respectively. Epinephrine (NE) was measured at TO, T1, T5, and T9, concentrations of IL-1 and IL-6 were measured at TO, T5, 24 h after surgery ( T10) , 48 h after surgery (T11), respectively. Results Compared with group C, MAP at T4 and T5 and HR at T1-T5 all de- creased, PAED scale and MCHEOPS decreased at T5-T9, NE concentrations were significantly reduced at T5 and T9, concentrations of IL-1 and IL-6 decreased at T5, T10, T1 1 in group T (P <0. 05, P <0. 01). Compared with group C, the total dose of propofol, times for propofol dose adjustment, average target concentration were reduced in group T during surgery (P <0. 05, P <0. 01). Twenty cases (67%) used propofol in group C and 9 cases (30% ) used propofol in group T during surgery, with statistical difference (P <0. 01). Changes of BIS was not statistically different between the two groups (P >0. 05). Conclusion TEAS could inhibit stress response and inflammatory response of children patients, stabilize their hemo- dynamics during surgery, thereby reducing propofol dose in closed-loop anesthesia delivery system.

METTL14-mediated upregulation of lncRNA HOTAIR represses PP1α expression by promoting H3K4me1 demethylation in oxycodone-treated mice.

N6-methyladenosine (m6A) methylation is a vital epigenetic mechanism associated with drug addiction. However, the relationship between m6A modification and oxycodone rewarding is less well explored. Based on an open field test, the present study evaluated oxycodone rewarding using chromatin immunoprecipitation PCR, immunofluorescence, and RNA sequencing. A marked increase in METTL14 protein and a decrease in PP1α protein due to oxycodone abundance in the striatal neurons were observed in a dose- and time-dependent manner. Oxycodone markedly increased LSD1 expression, and decreased H3K4me1 expression in the striatum. In the open field test, intra-striatal injection of METTL14 siRNA, HOTAIR siRNA, or LSD1 shRNA blocked oxycodone-induced increase in locomotor activity. The downregulation of PP1α was also inhibited after treatment with METTL14/HOTAIR siRNA and LSD1 shRNA. Enhanced binding of LSD1 with CoRest and of CoRest with the PP1α gene induced by oxycodone was also reversed by LSD1 shRNA. In addition, H3K4me1 demethylation was also blocked by the treatment. In summary, the investigation confirmed that METTL14-mediated upregulation of HOTAIR resulted in the repression of PP1α, which in turn facilitated the recruitment of LSD1, thus catalyzing H3K4me1 demethylation and promoting oxycodone addiction.

The epigenetically regulated PP1α expression by KDM1A may contribute to oxycodone conditioned place preference in mice.

The lysine-specific demethylase 1 (KDM1A) is reported to be a regulator in learning and memory. However, the effect of KDM1A in oxycodone rewarding memory has yet to be studied. In our study, rewarding memory was assessed by using conditioned place preference (CPP) in male mice. Next generation sequencing and chromatin immunoprecipitation-PCR were used to explore the molecular mechanisms. Oxycodone significantly decreased PP1α mRNA and protein levels in hippocampal neurons. Oxycodone significantly increased KDM1A and H3K4me1 levels, while significantly decreased H3K4me2 levels in a time- and dose-dependent manner. Behavioral data demonstrated that intraperitoneal injection of ORY-1001 (KDM1A inhibitor) or intra-hippocampal injection of KDM1A siRNA/shRNA blocked the acquisition and expression of oxycodone CPP and facilitated the extinction of oxycodone CPP. The decrease of PP1α was markedly blocked by the injection of ORY-1001 or KDM1A siRNA/shRNA. Oxycodone-induced enhanced binding of CoRest with KDM1A and binding of CoRest with the PP1α promoter was blocked by ORY-1001. The level of H3K4me2 demethylation was also decreased by the treatment. The results suggest that oxycodone-induced upregulation of KDM1A via demethylation of H3K4me2 promotes the binding of CoRest with the PP1α promoter, and the subsequent decrease in PP1α expression in hippocampal neurons may contribute to oxycodone reward.

Effects of Transcutaneous Electrical Acupoint Stimulation on the Stress Response During Extubation After General Anesthesia in Elderly Patients Undergoing Elective Supratentorial Craniotomy: A Prospective Randomized Controlled Trial.

BACKGROUND: Elderly patients have an increased risk of a stress response during extubation after general anesthesia. In this study, we aimed to investigate whether transcutaneous electrical acupoint stimulation (TEAS) might decrease the stress response and improve the quality of recovery in elderly patients after elective supratentorial craniotomy. MATERIALS AND METHODS: In this prospective randomized controlled study, patients were randomly assigned to either a TEAS group (n=37) or a control group (n=38). The primary outcomes were the hemodynamic parameters and plasma concentrations of epinephrine, norepinephrine, and cortisol. The secondary outcome included the consumption of remifentanil and propofol, time to extubation and reorientation, extubation quality score, postoperative quality of recovery, and postoperative complications. RESULTS: Compared with the control group, hemodynamic parameters and plasma concentrations of epinephrine, norepinephrine, and cortisol during extubation were decreased in the TEAS group. TEAS reduced the consumption of remifentanil (P<0.01), as well as incidence of postoperative complications. The extubation quality score was lower (P<0.01) and the quality of recovery score was higher (P<0.01) in the TEAS group than in the control group. However, the time to extubation and reorientation, and the consumption of propofol were not significantly different between the 2 groups. CONCLUSIONS: TEAS may decrease the stress response during extubation, improve quality of postoperative recovery, and decrease incidence of postoperative complications in elderly patients undergoing elective supratentorial craniotomy.