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Background Mental disorders in drug users have received increasing attention. However, there are no any epidemiologic data available in regard to substance use disorders (SUD) and other mental disorders in drug users in Yunnan, one region that is hit hardest by epidemic of drug use in China. Objective To investigate the co-prevalence of SUD and a common mental disorder, axisⅠdisorders, among Yunnan's drug users. Methods A cross-sectional survey was conducted among a convenient sample of 598 male drug users who received detoxification treatment from the 5th Compulsory Detention and Forced Detoxification Center of Yunnan Province and Dali Compulsory Detention and Forced Detoxification Center between August and November, 2020. According to the diagnosis of SUD, the participants were divided into three groups: opioid use disorder group (n=245) , methamphetamine use disorder group (n=197) and double use disorder group (n=146) . The Chinese version of SCID-Ⅰ/P was used to assess the prevalence of common axisⅠmental disorders (psychosis disorder, affective disorder, alcohol use disorder, and sedative-hypnotic use disorder) . The lifetime prevalence of these disorders among the three groups was compared. Results Among the 598 cases, there were 588 cases diagnosed with SUD (opioid, methamphetamine, or both) . The lifetime prevalence of psychosis disorder, alcohol use disorder, sedative and hypnotic use disorder among the three groups was significantly different (P < 0.05) . The overall lifetime prevalence of schizophrenia, other primary and drug induced psychotic disorders was 15.82%. The lifetime prevalence of psychotic disorder in opioid use disorder group (5.31%) was lower than that of methamphetamine use disorder group (20.30%) or that of double use disorder group (27.40%) (P

Preclinical studies suggest that the GABA B receptor is a potential target for treatment of substance use disorders. Baclofen (BLF), a prototypical GABA B receptor agonist, is the only specific GABA B receptor agonist available for application in clinical addiction treatment. The nucleus accumbens shell (AcbSh) is a key node in the circuit that controls reward-directed behavior. However, the relationship between GABA B receptors in the AcbSh and memory reconsolidation was unclear. The aim of this study was to investigate the effect of intra-AcbSh injection of BLF on the reconsolidation of morphine reward memory. Male C57BL/6J mice were used to establish morphine conditioned place preference (CPP) model and carry out morphine reward memory retrieval and activation experiment. The effects of intra-AcbSh injection of BLF on morphine-induced CPP, reinstatement of CPP and locomotor activity were observed after environmental cues activating morphine reward memory. The results showed that intra-AcbSh injection of BLF (0.06 nmol/0.2 μL/side or 0.12 nmol/0.2 μL/side), rather than vehicle or BLF (0.01 nmol/0.2 μL/side), following morphine reward memory retrieval abolished morphine-induced CPP by disrupting its reconsolidation in mice. Moreover, this effect persisted for more than 14 days, which was not reversed by a morphine priming injection. Furthermore, intra-AcbSh injection of BLF without morphine reward memory retrieval had no effect on morphine-associated reward memory. Interestingly, administration of BLF into the AcbSh had no effect on the locomotor activity of mice during testing phase. Based on these results, we concluded that intra-AcbSh injection of BLF following morphine reward memory could erase morphine-induced CPP by disrupting its reconsolidation. Activating GABA B receptor in AcbSh during drug memory reconsolidation may be a potential approach to prevent drug relapse.

Objective: To explore the neuromechanism of nicotine dependence, structural covariation networks (SCNs) based on voxel-based morphometry (VBM) were used to study the synergistic changes in gray matter volume in different cerebral cortices of nicotine dependent individuals. Methods: During the period from August 2016 to February 2018, a total of 118 long-term smokers and 57 non-smoking healthy controls (both 18-55 male volunteers) through online platforms and leaflets were recruited. The subjects were scanned with SIEMENS Skyro 3.0T magnetic resonance scanner and underwent routine MRI sequence (preliminary elimination of intracranial lesions) and 3D-T1 (3D-mprage) sequence structure. Two imaging experts used Matlab software platform to carry on segmentation by using SPM8, and to find out the differences between the two groups of brain regions, and differences in brain regions as region of interest (ROI) structure association network analysis. Results: The gray matter volume (GMV) of the right anterior central gyrus and the left inferior parietal lobe in the smoking group decreased(voxels size were 55 and 284, respectively), and no gray matter volume (GMV) area increased. The network structure of covariant analysis found that when the inferior parietal lobe as the seed points, the smoking group showed a rising trend in left parietal lobe and left temporal pole, bilateral middle temporal gyrus, left postcentral gyrus and right middle frontal gyrus gray matter volume, and a downtrend in the right side of the left medial frontal gyrus, superior parietal lobe, bilateral temporal gyrus, left cingulate gyrus and left cerebellum (central) compared with the control group. Conclusion: In long-term smokers, there is a volume change of gray matter in the brain structure. Abnormal changes in the structure covariant network of the inferior parietal lobe can lead to impaired brain function in nicotine dependent patients.

Behavioral studies indicate that nucleus accumbens (NAcc) is a key brain area for the rewarding effects of opiate and for opiate addiction. To find out the cellular correlates of opiate addiction, the effects of three kinds of opiate peptides on membrane potential and postsynaptic potentials (PSPs) in a slice preparation of NAcc were studies by intracellular recording and current-clamp technique. The results indicated that superfusion of opioid 7 peptides did not affect membrane potential and input resistance of NAcc neurons, but significantly reduced postsynaptic potentials. Naloxone superfusion significantly reversed the depressant effects of mu and sigma receptor agonist (DAGO, D-Pen) on PSPs, but not on those of kappa agonist (U-50). These results suggest that opioid peptides predominantly reduce synaptic transmission in NAcc.

A rapid and simple method for the quantitative determination of opioid dependence and tolerance in the guinea pig ileum was introduced. Dependence, as indicated by a strong contraction of the ileum when challenged with naloxone, was produced by incubating ileum from native guinea pig with opioid at 37 degrees C for 1-6 h. The response of the ileum to naloxone was time-dependent and directly related to the normorphine concentration in the incubation fluid (10-1000 nmol/L) and to the challenge dose of naloxone (10-1000 nmol/L). There were lower naloxone-precipitated withdrawal responses in the guinea pig ileum incubated with pethidine, nalorphine and ohmefentanyl than with fentanyl, U50488H and morphine. Buprenorphine showed no withdrawal response. In spite of rapid development of dependence, segments of ileum incubated with normorphine at low concentration (10-300 nmol/L) showed no or slight tolerance to normorphine (3-fold). Only by incubating with high concentration of normorphine (1 mumol/L) was high tolerance detected. The results indicate that opioid dependence and tolerance do not develop in parallel.