Methamphetamine withdrawal induces activation of CRF neurons in the brain stress system in parallel with an increased activity of cardiac sympathetic pathways

Catechol-O-Methyltransferase inhibition and alcohol use disorder: Evaluating the efficacy of tolcapone in ethanol-dependent rats

Alcohol Use Disorder (AUD) is a significant public health issue in the United States. It affects millions of individuals and their families and contributes to substantial societal and economic burdens. Despite the availability of some pharmacological treatments, there is still a pressing need to develop more effective therapeutic strategies to address the diverse range of symptoms and challenges associated with AUD. Catechol-O-methyltransferase (COMT) inhibition recently emerged as a promising new approach to treating AUD due to its potential to improve cognitive effects commonly associated with AUD. Tolcapone, an FDA-approved COMT inhibitor, has shown some promise for treating AUD; however, its ability to decrease drinking in ethanol-dependent rats has not been well-established. In this study, we evaluated the effects of tolcapone on operant, oral ethanol self-administration in non-dependent and dependent rats, and in rats that self-administered oral saccharin. To induce dependence, rats underwent the chronic intermittent exposure to vapor model, and their drinking levels were assessed during acute withdrawal from ethanol. Our results demonstrated that tolcapone attenuated responding for ethanol in dependent rats only, without affecting self-administration in non-dependent rats or rats self-administering saccharin. Moreover, we found that tolcapone was differentially effective in different estrous phases in female rats. These findings suggest that COMT inhibition, specifically using tolcapone, may be a valuable pharmacotherapy for treating AUD, particularly in individuals who are physically dependent on alcohol. Further research is needed to elucidate the precise mechanisms underlying the observed effects and to assess the potential of COMT inhibitors in a broader population of individuals with AUD.

Upregulation of Heat-Shock Protein (hsp)-27 in a Patient with Heterozygous SPG11 c.1951C>T and SYNJ1 c.2614G>T Mutations Causing Clinical Spastic Paraplegia

We report a 49-year-old patient suffering from spastic paraplegia with a novel heterozygous mutation and analyzed the levels of heat shock proteins (hsp)-27, dopamine (DA), and its metabolites in their cerebrospinal fluid (CSF). The hsp27 protein concentration in the patient's CSF was assayed by an ELISA kit, while DA levels and its metabolites in the CSF, 3,4-dihydroxyphenylacetic acid (DOPAC), Cys-DA, and Cys-DOPA were measured by HPLC. Whole exome sequencing demonstrated SPG-11 c.1951C>T and novel SYNJ1 c.2614G>T mutations, both heterozygous recessive. The patient's DA and DOPAC levels in their CSF were significantly decreased (53.0 ± 6.92 and 473.3 ± 72.19, p < 0.05, respectively) while no differences were found in their Cys-DA. Nonetheless, Cys-DA/DOPAC ratio (0.213 ± 0.024, p < 0.05) and hsp27 levels (1073.0 ± 136.4, p < 0.05) were significantly higher. To the best of our knowledge, the c.2614G>T SYNJ1 mutation has not been previously reported. Our patient does not produce fully functional spatacsin and synaptojanin-1 proteins. In this line, our results showed decreased DA and DOPAC levels in the patient's CSF, indicating loss of DAergic neurons. Many factors have been described as being responsible for the increased cys-DA/DOPAC ratio, such as MAO inhibition and decreased antioxidant activity in DAergic neurons which would increase catecholquinones and consequently cysteinyl-catechols. In conclusion, haploinsufficiency of spatacsin and synaptojanin-1 proteins might be the underlying cause of neurodegeneration produced by protein trafficking defects, DA vesicle trafficking/recycling processes, autophagy dysfunction, and cell death leading to hsp27 upregulation as a cellular mechanism of protection and/or to balance impaired protein trafficking.

Targeted Therapy for Orofacial Pain: A Novel Perspective for Precision Medicine

Orofacial pain (OFP) is a dental specialty that includes the diagnosis, management and treatment of disorders of the jaw, mouth, face, head and neck. Evidence-based understanding is critical in effectively treating OFPs as the pathophysiology of these conditions is multifactorial. Since OFP impacts the quality of life of the affected individuals, treating patients successfully is of the utmost significance. Despite the therapeutic choices available, treating OFP is still quite challenging, owing to inter-patient variations. The emerging trends in precision medicine could probably lead us to a paradigm shift in effectively managing the untreatable long-standing pain conditions. Precision medicine is designed based on the patient's genetic profile to meet their needs. Several significant relationships have been discovered based on the genetics and genomics of pain in the past, and some of the notable targets are discussed in this review. The scope of this review is to discuss preclinical and clinical trials that include approaches used in targeted therapy for orofacial pain. Future developments in pain medicine should benefit from current trends in research into novel therapeutic approaches.

Amphetamine exposure alters behaviors, and neuronal and neurochemical activation in the brain of female prairie voles

Previous studies have shown that 3-day d-amphetamine (AMPH) treatment effectively induced conditioned place preferences (CPP) and impaired pair bonding behaviors in prairie voles (Microtus ochrogaster). Using this established animal model and treatment regimen, we examined the effects of the demonstrated threshold rewarding dose of AMPH on various behaviors and their potential underlying neurochemical systems in the brain of female prairie voles. Our data show that 3-day AMPH injections (0.2 mg/kg/day) impaired social recognition and decreased depressive-like behavior in females without affecting their locomotion and anxiety-like behaviors. AMPH treatment also decreased neuronal activation indicated by the labeling of the early growth response protein 1 (Egr-1) as well as the number of neurons double-labeled for Egr-1 and corticotrophin-releasing hormone (CRH) in the dentate gyrus (DG) of the hippocampus and paraventricular nucleus of the hypothalamus (PVN) in the brain. Further, AMPH treatment decreased the number of neurons double-labeled for Egr-1 and tyrosine hydroxylase (TH) but did not affect oxytocinergic neurons in the PVN or cell proliferation and neurogenesis markers in the DG. These data not only demonstrate potential roles of the brain CRH and dopamine systems in mediating disrupted social recognition and depressive-like behaviors by AMPH in female prairie voles, but also further confirm the utility of the prairie vole model for studying interactions between psychostimulants and social behaviors.

Mechanism of Catechol-O-methyltransferase Regulating Orofacial Pain Induced by Tooth Movement

OBJECTIVE

To explore the mechanism of catechol-O-methyltransferase (COMT) in tooth movement pain.

METHODS

The experimental groups were randomly allocated into the healthy control, sham operation, model, model+shCOMT experimental, model+shCOMT control, and model+COMT antagonist groups. A tooth movement pain model was established. The pain stimulation and behavior test were performed. The duration of grooming behavior was determined. The appropriate experimental force and duration for application were selected. COMT shRNA vector was constructed and packaged as adenovirus. The shCOMT adenovirus was injected into the left infraorbital foramen. Seven days later, the trigeminal ganglia of all treatment groups were obtained. The COMT and IL-17 expressions were detected by western blot. The appropriate COMT antagonist concentration was selected. The pathological results of each group were detected by HE staining. The tooth movement distance was determined. The COMT gene expression was detected by FISH. The COMT and IL-17 expressions in the right trigeminal ganglion tissue of each group were detected by western blot.

RESULTS

The 60 g force and 14-day duration required the lowest stimulus intensity, the duration of grooming behavior was the longest, and the effect on COMT and IL-17 was the most significant. In the model group, formation of digestive cavity was seen in the trigeminal ganglion tissue, with infiltration of inflammatory cells, upregulation of the COMT and IL-17 expressions, and significant increase in the tooth movement distance. Compared with the model group, the shCOMT experimental group and the COMT antagonist group significantly improved the trigeminal ganglion tissue injury, significantly decreased the tooth movement distance, and significantly inhibited the COMT and IL-17 expressions.

CONCLUSION

The efficiency of tooth movement can be influenced by interfering the COMT-related gene expression. This proves that the COMT system can regulate the orthodontic tooth movement pain.

Sex- and Brain Region-specific Changes in Gene Expression in Male and Female Rats as Consequences of Methamphetamine Self-administration and Abstinence

Sex differences in METH use exist among human METH users and in animal models of METH addiction. Herein, we tried to identify potential differences in gene expression between female and male rats after Methamphetamine self-administration (METH SA). Rats were trained to self-administer METH using two 3-hours daily sessions for 20 days. Cue-induced drug seeking was measured on withdrawal days 3 (WD3) and 30 (WD30). Rats were euthanized twenty-four hours after WD30. Prefrontal cortex (PFC) and hippocampus (HIP) were dissected to measure mRNA expression. Both female and male rats increased their METH intake and showed increased METH seeking during withdrawal. Female had higher basal level expression of hypocretin receptor 1 (Hcrtr1) and prodynorphin (Pdyn) mRNAs in the PFC and HIP. Basal corticotropin releasing hormone receptor 1 (Crhr1), Crh receptor 2 (Crhr2), hypocretin receptor 2 (Hcrtr2) and opioid receptor kappa 1 (Oprk1) mRNA levels were higher in the PFC of females. Male rats had higher basal levels of Crh and Crhr1 in HIP. METH SA was associated with increased Crh and Crhr1 in the HIP of both sexes and Crhr2 only in female HIP. Importantly, increased Crh and Crhr1 mRNA levels correlated positively with incubation of METH craving in both sexes, supporting their potential involvement, in part, in the regulation of this behavioral phenomenon. When taken together, our results identified sexual dimorphic baseline differences in rats. We also detected dimorphic responses in animals that had self-administered METH. These observations highlight the importance of understanding the molecular neurobiology of sex differences when therapeutic interventions are planned against METH addiction.

Long-term exposure to ephedrine leads to neurotoxicity and neurobehavioral disorders accompanied by up-regulation of CRF in prefrontal cortex and hippocampus in rhesus macaques

Drug addiction continues to threaten the health and welfare of people worldwide, and ephedrine abuse is a serious drug problem in many areas of the world. Ephedrine toxicity is thought to induce behavioral effects primarily through actions on the central nervous system. The corticotropin-releasing factor (CRF) system plays an important role in regulating behavioral effects induced by addictive drugs, but whether CRF is related to ephedrine toxicity remains unclear. This study seeks to examine whether there is a correlation between the CRF and chronic ephedrine neurotoxicity. To this end, we established a chronic ephedrine (0.4-1.6 mg/kg/d) exposure model in rhesus macaques, assessed its effects on body weight and behavior, examined neuronal changes in the prefrontal cortex and hippocampus, and measured the CRF expression in the prefrontal cortex and hippocampus. After 8-weeks of exposure to ephedrine, the toxic effects of ephedrine included significant weight loss and induction of behavioral changes in rhesus macaques. In particular, in the modeling group, the abnormal behavioral changes mainly manifested as irritability and behavioral sensitization. Meanwhile, the histological abnormalities included neuronal morphological changes, pyknosis and irregular shapes of neurons in the prefrontal cortex and hippocampus. In addition, the expression levels of CRF mRNA and protein were increased in the prefrontal cortex and hippocampus of ephedrine-treated animals. In summary, the finding of this study indicated that ephedrine neurotoxicity can cause neuronal damage in cerebral cortex, which in turn can result in certain neurobehavioral abnormalities, and that CRF expression in prefrontal cortex and hippocampus is elevated in response to ephedrine exposure. These observations suggested that long-term exposure to ephedrine might be causing neurotoxicity and leading to neurobehavioral disorders accompanied by up-regulation of CRF in prefrontal cortex and hippocampus.

Cardiac Protective Role of Heat Shock Protein 27 in the Stress Induced by Drugs of Abuse

Heat shock proteins (HSP) are induced after different stress situations. Some of these proteins, particularly HSP-27, function as markers to indicate cellular stress or damage and protect the heart during addictive processes. Morphine withdrawal induces an enhancement of sympathetic activity in parallel with an increased HSP-27 expression and phosphorylation, indicating a severe situation of stress. HSP-27 can interact with different intracellular signaling pathways. Propranolol and SL-327 were able to antagonize the activation of hypothalamic-pituitary adrenal (HPA) axis and the phosphorylation of HSP-27 observed during morphine withdrawal. Therefore, β-adrenergic receptors and the extracellular signal-regulated kinase (ERK) pathway would be involved in HPA axis activity, and consequently, in HSP-27 activation. Finally, selective blockade of corticotrophin releasing factor (CRF)-1 receptor and the genetic deletion of CRF1 receptors antagonize cardiac adaptive changes. These changes are increased noradrenaline (NA) turnover, HPA axis activation and decreased HSP-27 expression and phosphorylation. This suggests a link between the HPA axis and HSP-27. On the other hand, morphine withdrawal increases µ-calpain expression, which in turn degrades cardiac troponin T (cTnT). This fact, together with a co-localization between cTnT and HSP-27, suggests that this chaperone avoids the degradation of cTnT by µ-calpain, correcting the cardiac contractility abnormalities observed during addictive processes. The aim of our research is to review the possible role of HSP-27 in the cardiac changes observed during morphine withdrawal and to understand the mechanisms implicated in its cardiac protective functions.

Stress-induced neural activation is altered during early withdrawal from chronic methamphetamine

Chronic methamphetamine (MA) use can lead to increased symptoms of depression and anxiety during abstinence. Less is known about the specific brain regions that are altered following repeated MA that may be associated with these behavioral perturbations. Furthermore, MA has been reported to recruit and activate microglia in the brain, which may exacerbate stress-associated behavioral changes. In the present study, male and female mice were injected with MA (5 mg/kg) or saline once daily for 10 days, and during early withdrawal were assessed for alterations in immediate early gene (c-Fos) responses to a forced swim stressor. Chronic MA exposure increased floating and decreased swim time in the forced swim test in male and female mice tested 48 h after the final dose, indicating elevated depressive-like behavior. Furthermore, assessment of nest building, a measure of distress or despair-like behavior, revealed a sex-specific effect with only MA-treated females showing impairments. The c-Fos response to forced swim was attenuated by prior MA exposure in the central amygdala, CA3 hippocampal region, prefrontal cortex, and bed nucleus of the stria terminalis (BST). In the BST this attenuation occurred only in males. Neither the total number of microglia or activated microglia were altered by chronic MA exposure in regions examined. The primary findings indicate that chronic MA exposure attenuates activation of select stress-associated brain regions, a dysregulation that might contribute to alterations in mood-related behaviors.