Knowledge and Attitudes of Clinical Trials among Patients with Rare Diseases and the Guardians in China.

BACKGROUND: Conducting of clinical trials for rare diseases faces multiple challenges. Patients' cognition and attitude toward clinical trials are crucial, which may affect their participation and compliance, and affect the schedule of clinical trials eventually. OBJECTIVE AND METHOD: This study aims to explore the knowledge and attitudes of clinical trials of patients with rare diseases or patients' guardians. An anonymous cross-sectional survey was conducted from November 1, 2021, to November 30, 2021. A total of 1131 valid questionnaires were included. Among them, 417 were filled in by the patients themselves, and 714 were answered by the patients' guardians. RESULTS: The average score of clinical trial knowledge of the patients (8.25) was lower than that of the guardians (8.85). The willingness of the patients to participate in clinical trials was high (4.28), and the willingness of the patients' guardians was also high for patients to participate in clinical trials (4.35). The main promoting factors of clinical trial participation were the possibility of curing the disease. The main hindering factors of participation in clinical trials were lack of access to clinical trial information and concern about the safety and effectiveness of the trial drug. CONCLUSIONS: In conclusion, most respondents had some basic knowledge of clinical trials and high willingness to participate in clinical trials. But there were some cognitive deficiencies about clinical trials and many hindering factors to participate in clinical trials. Clinical trials of rare diseases should be patient-centered and truly meet the unmet clinical, psychological, and social needs of patients with rare diseases.

RAGE signaling pathway is involved in CUS-induced depression-like behaviors by regulating the expression of NR2A and NR2B in rat hippocampus DG.

NMDA receptors play pivotal roles in the neurobiology of chronic stress-induced mood disorders. But the mechanism for chronic stress to disturb the expression of NMDA receptor subunits is still unclear. Recent researches indicated the involvement RAGE signaling pathway in regulation of glutamate system functions. In this study, we hypothesized RAGE signaling pathway mediated chronic stress-induced alteration in the expression of NMDA receptor subunits, leading to depressive-like behaviors. CUS decreased the expression of RAGE, NR2A, and NR2B, inhibited the phosphorylation of transcript factor ERK and CREB in rat hippocampus DG. RAGE knockdown in hippocampus DG by RAGE shRNA lentiviral particles induced depressive-like behaviors, reduced the mRNA and protein expression of NR2A and NR2B, and inhibited the phosphorylation of ERK and CREB. RAGE over-expression in hippocampus DG by RAGE adenovirus particles reversed the effects of CUS on depressive-like behaviors, ERK and CREB phosphorylation, and NR2A and NR2B expression. Our findings suggests that RAGE signaling pathway at least partially participates in the regulation of NR2A and NR2B expression, which mediates the effects of chronic stress on the depressive-like behaviors. These data provide evidence for RAGE signaling as a possible new pathway through which chronic stress results in the maladaptation of NMDA receptors.

Current status and trend of clinical development of orphan drugs in China.

BACKGROUND: Rare diseases have been increasingly recognized as unmet medical and health needs worldwide; a growing demand for the development of orphan drugs emerges subsequently. Therefore, it is of great interest for both the Chinese regulatory agency and pharmaceutical companies to keep tract on the clinical development of orphan drugs in China. OBJECTIVE AND METHOD: This study aims to reveal the current situation and trend of the clinical development of orphan drugs in China, based on the data collected from the Chinese official platform, dating from January 1, 2013 to December 31, 2021. RESULTS: A total of 331 clinical trials for orphan drugs were extracted from the platform, covering 31 rare diseases and 124 drugs. Increases were seen in the annual number of clinical trials and drugs being tested, with a sharp increase after 2018. About the disease types of the 331 trials, Parkinson disease (young-onset, early-onset) (86, 26%), hemophilia (70, 21%), homozygote hypercholesterolemia (60, 18%) were the most common. Furthermore, it was also observed that the largest number of clinical trial units for rare disease in east China (90, 41%) and the smallest number located in northwest China (18, 6%) and northeast China (18, 6%). CONCLUSIONS: The growth trends illustrate the progress in clinical trial and drug development of rare diseases from 2013 to 2021. However, promoting orphan drugs development still is an important issue in China; at the same time, further efforts should be made for meet the unmet needs of disease types and balance the uneven distribution of medical resources for clinical trial on rare diseases.

Distinct Role of Mono-2-ethylhexyl Phthalate in Neuronal Transmission in Rat CA3 Hippocampal Neurons: Involvement of Ion Channels.

Mono-(2-ethylhexyl) phthalate (MEHP) is one of the main active metabolites of di-(2-ethylhexyl) phthalate (DEHP). In our previous works, by using rat and Drosophila models, we showed a disruption of neural function due to DEHP. However, the exact neural effects of MEHP are still unclear. To explore the effects of MEHP on the central nervous system, the electrophysiological properties of spontaneous action potential (sAP), mini-excitatory postsynaptic currents (mEPSCs), ion channels, including Na+, Ca2+, and K+ channels from rat CA3 hippocampal neurons area were assessed. Our data showed that MEHP (at the concentrations of 100 or 300 µM) decreased the amplitude of sAP and the frequency of mEPSCs. Additionally, MEHP (100 or 300 µM) significantly reduced the peak current density of Ca2+ channels, whereas only the concentration of 300 µM decreased the peak current density of Na+ and K+ channels. Therefore, our results indicate that exposure to MEHP could affect the neuronal excitability and synaptic plasticity of rat CA3 hippocampal neurons by inhibiting ion channels' activity, implying the distinct role of MEHP in neural transmission.

A Novel Etomidate Analog EL-0052 Retains Potent Hypnotic Effect and Stable Hemodynamics without Suppressing Adrenocortical Function.

Etomidate is a potent and rapidly acting anesthetic with high therapeutic index (TI) and superior hemodynamic stability. However, side effect of suppressing adrenocortical function limits its clinical use. To overcome this side effect, we designed a novel etomidate analog, EL-0052, aiming to retain beneficial properties of etomidate and avoid its disadvantage of suppressing adrenocortical steroid synthesis. Results exhibited that EL-0052 enhanced GABAA receptors currents with a concentration for EC50 of 0.98 ± 0.02 µM, which was about three times more potent than etomidate (3.07 ± 1.67 µM). Similar to hypnotic potency of etomidate, EL-0052 exhibited loss of righting reflex with ED50s of 1.02 (0.93-1.20) mg/kg in rats and 0.5 (0.45-0.56) mg/kg in dogs. The TI of EL-0052 in rats was 28, which was higher than 22 of etomidate. There was no significant difference in hypnotic onset time, recovery time, and walking time between EL-0052 and etomidate in rats. Both of them had minor effects on mean arterial pressure in dogs. EL-0052 had no significant effect on adrenocortical function in dogs even at a high dose (4.3 × ED50), whereas etomidate significantly inhibited corticosteroid secretion. The inhibition of cortisol synthesis assay showed that EL-0052 had a weak inhibition on cortisol biosynthesis in human H259 cells with an IC50 of 1050 ± 100 nM, which was 2.09 ± 0.27 nM for etomidate. EL-0052 retains the favorable properties of etomidate, including potent hypnotic effect, rapid onset and recovery, stable hemodynamics, and high therapeutic index without suppression of adrenocortical function. SIGNIFICANCE STATEMENT: The novel etomidate analog EL-0052 retains the favorable properties of etomidate without suppressing adrenocortical function and provides a new strategy to optimize the structure of etomidate.

Discovery of the EL-0052 as a potential anesthetic drug.

As a γ-aminobutyric acid A receptor (GABAAR) inhibitor, etomidate fulfills several characteristics of an ideal anesthetic agent, such as rapid onset with rapid clearance and high potency, along with cardiovascular stability. Unfortunately, etomidate has been reported to inhibit CYP11B1 at hypnotic doses, which is associated with a marked increase in patient deaths due to this unexpected off-target effect. In this study, molecular docking was used to simulate the binding mode of etomidate with GABAAR and CYP11B1. Based on the in-depth analysis of the binding mode, strong electron-withdrawing group on the C4 position of the imidazole ring was introduced to reduce the charge density of the nitrogen, which is beneficial in reducing the coordination bond between the imidazole nitrogen and heme iron in CYP11B1, as well as in reducing the adrenocortical suppression. Based on the results of ADMET property prediction, MEP analysis, and molecular docking simulation, 4-fluoroetomidate (EL-0052) was designed and synthesized. In vivo studies in rats and mice confirmed that EL-0052 had the efficacy similar to etomidate, but without adrenocortical suppression. These findings suggested that EL-0052 was superior to etomidate and support the continued development of EL-0052 as a preclinical candidate as an anesthetic.

RAGE Signaling pathway in hippocampus dentate gyrus involved in GLT-1 decrease induced by chronic unpredictable stress in rats.

A pivotal role of glutamatergic neurotransmission in the pathophysiology of major depressive disorder (MDD) has been supported in preclinical and clinical studies. Glutamate transporters are responsible for rapid uptake of glutamate to maintain glutamate homeostasis. Down-regulation of glutamate transporters has been reported in MDD patients and animal models. However, the mechanism for stress-induced modulation of glutamate transporter expression is poorly understood. Receptor for advanced glycosylation end products (RAGE), a member of immunoglobulin family, is found expressed widely in brain and play important roles in neuronal development, neurite growth, neurogenesis and neuroinflammation. Our study showed chronic unpredictable stress (CUS) induced depressive-like behaviors and reduced RAGE expression in hippocampus DG, CA1 and CA3 areas. The protein levels of GLT-1, p-CREB and p-p65 decreased in hippocampus DG as well. Knockdown of RAGE expression in hippocampus DG with RAGE shRNA lentivirus particles induced depressive-like behaviors. Meanwhile, the protein and mRNA levels of GLT-1 were significantly decreased as well as phosphorylation of CREB and p65. Neither CUS nor RAGE knockdown altered GLAST protein and mRNA levels. These findings suggested that RAGE/CREB-NF-κB signaling pathway in hippocampus DG involved in modulation of GLT-1 expression, which possibly contributed to the depressive-like behavior induced by CUS.

In vitro and in vivo evaluation of liposomes modified with polypeptides and red cell membrane as a novel drug delivery system for myocardium targeting.

Ischemic cardiac disease (ICD) is a cardiovascular disease with high morbidity and mortality. In this study, a novel myocardial targeted drug delivery system was developed represented by co-modified liposomes consisting of red cell membrane (RCM), and the peptides TAT and PCM. Liposomes were prepared using a membrane dispersion-ultrasonic method; the prepared 1% TAT and 3% PCM micelles were mixed with liposomes and under overnight stirring to form polypeptid-modified liposomes. RCM was isolated from mice blood, and the mechanical force facilitated RCM adhesion to the lipid bilayer. The characteristics of liposomes such as the morphology, particle size, zeta-potential, and RCM-conjugation to lipsomes were evaluated. Uptake efficiency and cellular toxicity of liposomes were evaluated in vitro on myocardial cells (MCs). As regard the experiments in vivo, liposomes were intravenously injected into mice, and the blood and organs were collectedat different times to analyze the pharmacokinetics profile of liposomes. The cellular uptake and intracellular distribution of liposomes of different composition into MCs demonstrated that RCM-modified liposomes had the best delivery capability. The pharmacokinetics study further demonstrated that RCM-modified liposomes had prolonged mean residence time (MRT) and more accumulation in the heart. This study indicated that RCM can be used to modify liposomes in combination with polypeptides, because such modification increases the myocardial targeting of liposomes. Therefore, this system constructed in this study might be a potentially effective myocardial drug delivery system.

Metal-free and solvent-free synthesis of m-terphenyls through tandem cyclocondensation of aryl methyl ketones with triethyl orthoformate.

Reported here is a novel cyclocondensation of aryl methyl ketones and triethyl orthoformate for the simple synthesis of m-terphenyls. In the presence of a catalytic amount of TfOH, alkyl- and chloro-substituted acetophenones produced a series of terphenyls through a tandem reaction which merged six steps into a one-pot procedure. Moreover, the corresponding ester products were obtained when using other substituted acetophenones as the starting materials under the same reaction conditions.

One-Step Regioselective Synthesis of Benzofurans from Phenols and α-Haloketones.

Reported here is the direct synthesis of naphthofurans and benzofurans from readily available phenols and α-haloketones promoted by titanium tetrachloride which combines Friedel-Crafts-like alkylation and intramolecular cyclodehydration into one step. This simple protocol allows for the formation of a variety of high value naphthofurans and benzofurans within which a series of cyclic and acyclic groups are readily incorporated. This process demonstrates the advantages of high levels of regioselectivity, broad substrate scope, and moderate to excellent yields.

Changes in the levels of 12/15-lipoxygenase, apoptosis-related proteins and inflammatory factors in the cortex of diabetic rats and the neuroprotection of baicalein.

This study was designed to investigate the neuroprotective effects of baicalein and the effect of the cortical 12/15-lipoxygenase (12/15-LOX) pathway on diabetic cognitive dysfunction. Our results showed that spatial learning and memory ability, as well as cortex neurons, were significantly impaired after the onset of diabetes. The fasting blood glucose and random blood glucose levels in the model group were significantly higher than those in the normal group. The levels of TG and TC in the plasma of the model group were significantly increased, but there was no significant difference in the LDL level. The insulin content in the plasma of diabetic rats was significantly lower than that of the normal group. The levels of inflammatory factors and 12(S)-HETE were significantly increased in diabetic rats, as were the protein expression levels of cPLA2, 12/15-LOX, p38MAPK, phospho-p38MAPK, caspase-3, caspase-9 and Aß1-42; by contrast, protein expression of Bcl-2 was significantly decreased. Administration of baicalein was shown to improve the spatial learning and memory ability and significantly decrease the levels of inflammatory cytokines. However, baicalein did not significantly influence the levels of blood glucose, lipids or insulin in rats. Baicalein treatment significantly protected diabetes rats from neuron death; significantly attenuated the overexpression of cPLA2, 12/15-LOX, p38MAPK, phospho-p38MAPK, caspase-3, caspase-9 and Aß1-42; and upregulated the expression of Bcl-2. These findings suggest that baicalein improves the cognitive function of diabetic rats by directly acting in the brain rather than by regulating the levels of blood glucose, lipids or insulin. In addition, baicalein can protect rat cortical neurons from damage caused by diabetes via inhibiting the 12/15-LOX pathway and relieving inflammation and apoptosis of the central nervous system.

Association of serum C1q tumour necrosis factor-related protein 9 with the severity of lower extremity peripheral arterial disease in type 2 diabetes patients.

OBJECTIVE: Recent studies have indicated the implication of C1q tumour necrosis factor-related protein 9 in vascular pathology of atherosclerosis. This study first investigated the association of C1q tumour necrosis factor-related protein 9 and the severity of lower extremity peripheral arterial disease in type 2 diabetes mellitus patients. METHODS: A total of 200 patients with type 2 diabetes mellitus had ankle-brachial index examined in this cross-sectional study, 60 patients with ankle-brachial index of ⩽0.9 were diagnosed with peripheral arterial disease and further classified into mild, moderate and severe group with Vivid 7 diagnostic apparatus. RESULTS: C1q tumour necrosis factor-related protein 9 and adiponectin were higher in diabetes mellitus with severe peripheral arterial disease than diabetes mellitus with mild and moderate peripheral arterial disease groups. After adjustment of conventional atherosclerosis risk factors, C1q tumour necrosis factor-related protein 9 ( r = -0.627, p < 0.001) and adiponectin ( r = -0.431, p = 0.003) were negatively correlated with the severity of peripheral arterial disease. Logistic regression analysis showed C1q tumour necrosis factor-related protein 9 was independently associated with the severity of peripheral arterial disease (odds ratio = 0.272, 95% confidence interval = 0.08-0.927, p = 0.037). CONCLUSION: Serum C1q tumour necrosis factor-related protein 9 is negatively and independently associated with the severity of peripheral arterial disease in type 2 diabetes mellitus patients, suggesting the protective potentials of C1q tumour necrosis factor-related protein 9 in the progression of peripheral arterial disease in human type 2 diabetes mellitus.

Polydatin promotes apoptosis through upregulation the ratio of Bax/Bcl-2 and inhibits proliferation by attenuating the ß-catenin signaling in human osteosarcoma cells.

Osteosarcoma is the most prevalent primary malignant bone tumor mainly endangering young adults. In this study, we explore whether polydatin (PD), a glycoside form of resveratrol, is effective for osteosarcoma. Our results showed that PD dose-dependently inhibited proliferation and promoted apoptosis in 143B and MG63 osteosarcoma cells, examined by MTT assay and Annexin V-FITC apoptosis detection. Further, we found PD increased expression of Bax and attenuated expression of Bcl-2, and consequently augmented caspase-3 activity. Moreover, PD also dose-dependently inhibited ß-catenin signaling pathway as indicated by decreased ß-catenin expression and activity, while overexpression of ß-catenin by adenoviruses system could abrogate the anti-tumor effect of PD. Our finding indicated that PD could inhibit the proliferation by inhibiting the ß-catenin signaling and induce apoptosis via upregulation the ratio of Bax/Bcl-2 in human osteosarcoma cells.

Hippocampal CLOCK protein participates in the persistence of depressive-like behavior induced by chronic unpredictable stress.

RATIONALE: Circadian disturbances are strongly linked with major depression. The circadian proteins CLOCK and BMAL1 are abundantly expressed but function differently in the suprachiasmatic nucleus (SCN) and hippocampus. However, their roles in depressive-like behavior are still poorly understood. OBJECTIVES: To investigate the alterations of CLOCK and BMAL1 in the SCN and hippocampus in rats subjected to chronic unpredictable stress (CUS) and to explore the relationship of circadian protein and the depressive-like behavior. RESULTS: Together with depressive-like behavior induced by CUS, CLOCK and BMAL1 in the SC were inhibited during the light period, and the peak expression of CLOCK in the hippocampus was shifted from the dark to light period. BMAL1 expression in the hippocampus was not significantly changed. Two weeks after the termination of CUS, abnormalities of CLOCK in the CA1 and CA3 endured, with unchanged depressive-like behavior, but the expression of CLOCK and BMAL1 in the SCN recovered to control levels. Knockdown of the Clock gene in CA1 induced depressive-like behavior in normal rats. CLOCK in the SCN and hippocampus may participate in the development of depressive-like behavior. However, CLOCK in the hippocampus but not SCN was involved in the long-lasting effects of CUS on depressive-like behavior. BMAL1 in the hippocampus appeared to be unrelated to the effects of CUS on depressive-like behavior. CONCLUSION: CLOCK protein in the hippocampus but not SCN play an important role in the long-lasting depressive-like behavior induced by CUS. These findings suggest a novel therapeutic target in the development of new antidepressants focusing on the regulation of circadian rhythm.

Quetiapine enhances oligodendrocyte regeneration and myelin repair after cuprizone-induced demyelination.

Myelin and oligodendrocyte dysfunctions have been consistently found in patients with schizophrenia. The effect of antipsychotics on myelin disturbances is unknown. The present study examined the effects of quetiapine on oligodendrocyte regeneration and myelin repair in a demyelination animal model. C57BL/6 mice were fed with cuprizone (0.2% w/w) for 12 weeks to induce chronic demyelination and oligodendrocyte degeneration, after which cuprizone was withdrawn to allow recovery. Quetiapine (10mg/kg/day) or vehicle (water) was administrated orally to mice for 0, 2, 3, or 4 weeks after cuprizone withdrawal. Locomotor activity and Y-maze tests were used to evaluate behavioral changes in the mice. Immunohistochemical staining was used to detect morphological and biological changes in the brains. Cuprizone administration for 12 weeks resulted in severe demyelination, locomotor hyperactivity, and working memory impairment in mice. Remyelination occurred when cuprizone was withdrawn. Quetiapine treatment during the recovery period significantly improved the spatial working memory and increased myelin restoration. Quetiapine treatment also enhanced the repopulation of mature oligodendrocytes in the demyelinated lesions, which was associated with down-regulation of transcription factor olig2 in the process of cell maturation. The results of this study demonstrated that quetiapine treatment during the recovery period improves spatial working memory and promotes oligodendrocyte development and remyelination. This study supports the role of oligodendrocyte dysfunction in memory deficits in a schizophrenia mouse model and suggests that quetiapine may target oligodendrocytes and improve cognitive function.

Increased Cdk5/p35 activity in the dentate gyrus mediates depressive-like behaviour in rats.

Depression is one of the most pervasive and debilitating psychiatric diseases, and the molecular mechanisms underlying the pathophysiology of depression have not been elucidated. Cyclin-dependent kinase 5 (Cdk5) has been implicated in synaptic plasticity underlying learning, memory, and neuropsychiatric disorders. However, whether Cdk5 participates in the development of depressive diseases has not been examined. Using the chronic mild stress (CMS) procedure, we examined the effects of Cdk5/p35 activity in the hippocampus on depressive-like behaviour in rats. We found that CMS increased Cdk5 activity in the hippocampus, accompanied by translocation of neuronal-specific activator p35 from the cytosol to the membrane in the dentate gyrus (DG) subregion. Inhibition of Cdk5 in DG but not in the cornu ammonis 1 (CA1) or CA3 hippocampal subregions inhibited the development of depressive-like symptoms. Overexpression of p35 in DG blocked the antidepressant-like effect of venlafaxine in the CMS model. Moreover, the antidepressants venlafaxine and mirtazapine, but not the antipsychotic aripiprazole, reduced Cdk5 activity through the redistribution of p35 from the membrane to the cytosol in DG. Our results showed that the development of depressive-like behaviour is associated with increased Cdk5 activity in the hippocampus and that the Cdk5/p35 complex plays a key role in the regulation of depressive-like behaviour and antidepressant actions.

NMDA receptor glycine modulatory site in the ventral tegmental area regulates the acquisition, retrieval, and reconsolidation of cocaine reward memory.

RATIONALE AND OBJECTIVES: Accumulating clinical and preclinical studies have shown that the memories of the rewarding effects of drugs and their paired cues may contribute to relapse and persistent cocaine use. Glutaminergic actions in the ventral tegmental area (VTA) have been shown to regulate the rewarding effect of drugs and conditioned responses to drug-associated cues, but the role of the VTA in the acquisition, retrieval, and reconsolidation of cocaine cues is not yet known. METHODS: In the present study, we used 7-chlorothiokynurenic acid (7-CTKA), an N-methyl-D-aspartate (NMDA) receptor glycine modulatory site antagonist with no rewarding effects, to examine the role of the NMDA receptor glycine modulatory site in the acquisition, retrieval, and reconsolidation of cocaine-related reward memory using the conditioned place preference (CPP) paradigm. RESULTS: Separate groups of Sprague-Dawley rats were trained to acquire cocaine-induced CPP. Vehicle or 7-CTKA was microinjected into the VTA or substantia nigra (SN) (5 µg/µl) at different time points: 10 min before each CPP training session (acquisition), 10 min before the reactivation of CPP (retrieval), and immediately after the reactivation of CPP (reconsolidation). Cocaine-induced CPP was retested 24 h and 1 and 2 weeks after 7-CTKA administration. 7-CTKA microinjected into the VTA, but not SN, significantly impaired the acquisition, retrieval, and reconsolidation of cocaine-induced CPP without affecting cocaine-induced locomotion. CONCLUSIONS: Our findings suggest that the NMDA receptor glycine modulatory site in the VTA plays a major role in cocaine reward memory, and NMDA receptor glycine site antagonists may be potential pharmacotherapies for the management of relapse.

Chronic unpredictable stress induces a reversible change of PER2 rhythm in the suprachiasmatic nucleus.

Many clinical studies have shown that circadian rhythm abnormalities are strongly associated with major depression. The master clock of the circadian system in mammals is located in the suprachiasmatic nucleus (SCN) within the anterior hypothalamus, where Per1 and Per2 are essential core components of circadian rhythm oscillation. Chronic unpredictable stress (CUS) is a reliable animal model of depression with good face, predictive, and constructive validity. In the present study, we investigated the effects of CUS on the circadian expression of PER1 and PER2 in the SCN. We found that CUS led to depressive-like behavior and reduced the amplitude of PER2 oscillation in the SCN, which were blocked by 3 weeks of desipramine (DMI) treatment. 2 weeks after termination of CUS, the decreased peak of PER2 expression returned to control levels, whereas depressive-like behavior remained unchanged. Our findings suggest that the dampened amplitude of PER2 expression in the SCN may participate in the development of depressive-like behavior induced by CUS but is unlikely involved in the long-lasting effects of CUS on depressive-like behavior.

Effects of cannabinoid CB1 receptor antagonist rimonabant on acquisition and reinstatement of psychostimulant reward memory in mice.

Drug addiction processes are considered to be mainly controlled by the mesocorticolimbic dopamine system. Cannabinoids, a class of psychoactive drugs of abuse, elicit their rewarding and pharmacological effects through the endocannabinoid system. Previous research has indicated that dopaminergic neurons in the mesocorticolimbic system are also under the control of the endocannabinoid system. Recently, evidence has suggested that the endocannabinoid system may also participate in the modulation of the common reward system. The present study examined whether rimonabant, a cannabinoid CB1 receptor antagonist, disrupts the acquisition and reinstatement of psychostimulant reward memory measured by conditioned place preference (CPP). Mice were trained to acquire methamphetamine or cocaine-induced CPP. A priming injection of methamphetamine (0.5 mg/kg, i.p.) or cocaine (5 mg/kg, i.p.) was respectively given to reinstate methamphetamine or cocaine-induced CPP after extinction. Vehicle or rimonabant (1 or 3 mg/kg, i.p.) was administered at different time-points: 30 min before each CPP training session (acquisition) or 30 min before the priming injection (reinstatement). Rimonabant at doses of 1 and 3 mg/kg significantly inhibited the acquisition of methamphetamine- and cocaine-induced CPP. At the high dose (3 mg/kg), rimonabant disrupted the reinstatement of extinguished methamphetamine- or cocaine-induced CPP. These findings indicate that cannabinoid CB1 receptors play a major role in psychostimulant reward memory, and rimonabant may be a potential pharmacotherapy for psychostimulant addiction.

Circadian alteration in neurobiology during protracted opiate withdrawal in rats.

Protracted opiate withdrawal can extend for months of disrupted hormonal circadian rhythms. We examined rodent behaviors and these circadian disturbances in hormone and peptide levels as well as brain clock gene expression during 60 days of protracted withdrawal. Our behavioral tests included open field, elevated plus maze, and sucrose preference tests at 36 h, 10, 30, and 60 days after stopping chronic morphine. At these four assessment points, we collected samples every 4 h for 24 h to examine circadian rhythms in blood hormone and peptide levels and brain expression of rPER1, rPER2, and rPER3 clock genes. Decreased locomotor activity and elevated adrenocorticotropic hormone and melatonin levels persisted for 2 months after morphine withdrawal, but corticosterone was elevated only at 36 h and 10 days after withdrawal. Orexin levels were high at 36 h after withdrawal, but then reversed during protracted withdrawal to abnormally low levels. Beta-endorphin (ß-EP) levels showed no differences from normal. However, circadian rhythms were blunted for all of these hormones. Corticosterone, adrenocorticotropic hormone, and orexin blunting persisted at least for 60 days. The blunted circadian rhythm of ß-EP and melatonin recovered by day 60, but the peak phase of ß-EP was delayed about 8 h. Blunted circadian rhythms and reduced expression of rPER1, rPER2, and rPER3 persisted at least for 60 days in the suprachiasmatic nucleus, prefrontal cortex, nucleus accumbens core, central nucleus of the amygdala, Hippocampus, and ventral tegmental area. Circadian rhythms of rPER1 in the nucleus accumbens shell and basolateral nucleus of the amygdala and of rPER2 in the central nucleus of the amygdala were reversed. Disrupted circadian rhythms of rPER1, rPER 2, and rPER3 expression in reward-related brain circuits and blunted circadian rhythms in peripheral hormones and peptides may play a role in protracted opiate withdrawal and contribute to relapse.