Repeated morphine treatment influences operant and spatial learning differentially

Objective To investigate whether repeated morphine exposure or prolonged withdrawal could influence operant and spatial learning differentially. Methods Animals were chronically treated with morphine or subjected to morphine withdrawal. Then, they were subjected to two kinds of learning: operant conditioning and spatial learning. Results The acquisition of both simple appetitive and cued operant learning was impaired after repeated morphine treatment. Withdrawal for 5 weeks alleviated the impairments. Single morphine exposure disrupted the retrieval of operant memory but had no effect on rats after 5-week withdrawal. Contrarily, neither chronic morphine exposure nor 5-week withdrawal influenced spatial learning task of the Morris water maze. Nevertheless, the retrieval of spatial memory was impaired by repeated morphine exposure but not by 5-week withdrawal. Conclusion These observations suggest that repeated morphine exposure can influence different types of learning at different aspects, implicating that the formation of opiate addiction may usurp memory mechanisms differentially.

Avoidance of potentially harmful food cannot be socially transmitted between rats

The social transmission of food preferences(STFP) is a behavioural task of olfactory memory, in which an observer rat learns safe food odours from a demonstrator rat, and shows preference for this odour in a subsequent choice test. However, previous studies have failed to detect the transmission of information about food of potential danger and food aversion using STFP test. In this study, we tested how demonstrators' health affects the exchange of odour information and whether observers can learn danger information from an unhealthy demonstrator. As expected, the observer rat formed an odour preference after interacting with a demonstrator rat that had just eaten food containing a new odour, however, odour preference rather than aversion was also formed after interacting with a demonstrator rat injected with LiCl(used to induce gastric malaise). Furthermore, anaesthetized demonstrator rats and half-anaesthetized demonstrator rats, which showed obvious motor deficits suggesting an unhealthy state, also socially transmitted food preferences to observers. These results suggest that the social transmission of food preferences task is independent of a demonstrators' health, and that information about dangerous foods cannot be transmitted using this behavioural task.

Nucleus accumbens-linked executive control networks mediating reversal learning in tree shrew brain

DEAR EDITOR,Cognitive flexibility is crucial for animal survival but is frequently impaired in neuropsychiatric disorders.Although many brain structures and functional networks are involved in cognitive flexibility,the neural mechanisms underlying cooperation among specific functional networks remain unclear from a global perspective.In this study,[^(18)F]-fluorodeoxyglucose positron emission tomography(FDG-PET)was performed on 19 male tree shrews after four different visual discrimination tasks,including baseline,learning expert(LE),reversal naive(RN),and reversal expert(RE).

Basal physiological parameters in domesticated tree shrews (Tupaia belangeri chinensis)

Establishing non-human primate models of human diseases is an efficient way to narrow the large gap between basic studies and translational medicine. Multifold advantages such as simplicity of breeding, low cost of feeding and facility of operating make the tree shrew an ideal non-human primate model proxy. Additional features like vulnerability to stress and spontaneous diabetic characteristics also indicate that the tree shrew could be a potential new animal model of human diseases. However, basal physiological indexes of tree shrew, especially those related to human disease, have not been systematically reported. Accordingly, we established important basal physiological indexes of domesticated tree shrews including several factors: (1) body weight, (2) core body temperature and rhythm, (3) diet metabolism, (4) locomotor rhythm, (5) electroencephalogram, (6) glycometabolism and (7) serum and urinary hormone level and urinary cortisol rhythm. We compared the physiological parameters of domesticated tree shrew with that of rats and macaques. Results showed that (a) the core body temperature of the tree shrew was 39.59±0.05 °C, which was higher than that of rats and macaques; (b) Compared with wild tree shrews, with two activity peaks, domesticated tree shrews had only one activity peak from 17:30 to 19:30; (c) Compared with rats, tree shrews had poor carbohydrate metabolism ability; and (d) Urinary cortisol rhythm indicated there were two peaks at 8:00 and 17:00 in domesticated tree shrews, which matched activity peaks in wild tree shrews. These results provided basal physiological indexes for domesticated tree shrews and laid an important foundation for diabetes and stress-related disease models established on tree shrews.

Basal physiological parameters in domesticated tree shrews(Tupaia belangeri chinensis)

Establishing non-human primate models of human diseases is an efficient way to narrow the large gap between basic studies and translational medicine.Multifold advantages such as simplicity of breeding,low cost of feeding and facility of operating make the tree shrew an ideal non-human primate model proxy.Additional features like vulnerability to stress and spontaneous diabetic characteristics also indicate that the tree shrew could be a potential new animal model of human diseases.However,basal physiological indexes of tree shrew,especially those related to human disease,have not been systematically reported.Accordingly,we established important basal physiological indexes of domesticated tree shrews including several factors:(1)body weight,(2)core body temperature and rhythm,(3)diet metabolism,(4)locomotor rhythm,(5)electroencephalogram,(6)glycometabolism and(7)serum and urinary hormone level and urinary cortisol rhythm.We compared the physiological parameters of domesticated tree shrew with that of rats and macaques.Results showed that(a)the core body temperature of the tree shrew was 39.59±0.05°C,which was higher than that of rats and macaques;(b)Compared with wild tree shrews,with two activity peaks,domesticated tree shrews had only one activity peak from 17:30 to 19:30;(c)Compared with rats,tree shrews had poor carbohydrate metabolism ability;and(d)Urinary cortisol rhythm indicated there were two peaks at 8:00 and 17:00 in domesticated tree shrews,which matched activity peaks in wild tree shrews.These results provided basal physiological indexes for domesticated tree shrews and laid an important foundation for diabetes and stress-related disease models established on tree shrews.

Hypoxia-inducible factor upregulation by roxadustat attenuates drug reward by altering brain iron homoeostasis

Substance use disorder remains a major challenge,with an enduring need to identify and evaluate new,translational targets for effective treatment.Here,we report the upregulation of Hypoxia-inducible factor-1α(HIF-1α)expression by roxadustat(Rox),a drug developed for renal anemia that inhibits HIF prolyl hydroxylase to prevent degradation of HIF-1α,administered either systemically or locally into selected brain regions,suppressed morphine(Mor)-induced conditioned place preference(CPP).

STON2风险变异通过影响Syt1转运和突触功能导致精神分裂症样行为

Synaptic dysfunction is a core component of the pathophysiology of schizophrenia.However,the genetic risk factors and molecular mechanisms related to synaptic dysfunction are still not fully understood.The Stonin 2(STON2)gene encodes a major adaptor for clathrin-mediated endocytosis(CME)of synaptic vesicles.In this study,we showed that the C-C(307Pro-851Ala)haplotype of STON2 increases the susceptibility to schizophrenia and examined whether STON2 variations cause schizophrenia-like behaviors through the regulation of CME.We found that schizophrenia-related STON2 variations led to protein dephosphorylation,which affected its interaction with synaptotagmin 1(Syt1),a calcium sensor protein located in the presynaptic membrane that is critical for CME.STON2307Pro851Ala knockin mice exhibited deficits in synaptic transmission,short-term plasticity,and schizophrenia-like behaviors.Moreover,among seven antipsychotic drugs,patients with the C-C(307Pro-851Ala)haplotype responded better to haloperidol than did the T-A(307Ser-851Ser)carriers.The recovery of deficits in Syt1 sorting and synaptic transmission by acute administration of haloperidol effectively improved schizophrenia-like behaviors in STON2307Pro851Ala knockin mice.Our findings demonstrated the effect of schizophreniarelated STON2 variations on synaptic dysfunction through the regulation of CME,which might be attractive therapeutic targets for treating schizophrenia-like phenotypes.