Sustained escitalopram administration affects glucose metabolism in the rat brain.

Escitalopram is a selective serotonin reuptake inhibitor (SSRIs) antidepressant, drug that is currently used as first-line agents for the treatment of depression and it is also used in the treatment of other psychiatric disorders. The main goal of this study was to identify which brain areas are affected by escitalopram administration. This study was carried out on male Wistar rats that received escitalopram daily over 14 days and that were studied by 2-deoxy-2[18F]fluoro-D-glucose ([18F]FDG)-PET on the last day of treatment. Computed tomography (CT) images were acquired immediately before each PET scan and the main effects of drug administration were elucidated by Statistical Parametric Mapping. The results obtained indicated that repeated exposure to escitalopram increased metabolic activity in the retrosplenial and posterior cingulate cortices, while it decreased such activity in the ventral hippocampus, cerebellum, brainstem and midbrain regions, including the raphe nuclei and ventral tegmental area. Therefore, repeated exposure to escitalopram alters the activity of several brain areas closely related to the serotonergic system, and previously identified as key regions in the antidepressant effect induced by SSRIs. Furthermore, some of the changes found, such as the dampened metabolism in the ventral tegmental area, are similar to changes that have been described after treating with other fast-acting antidepressant approaches.

Monoaminergic system and depression.

Major depressive disorder is a severe, disabling disorder that affects around 4.7% of the population worldwide. Based on the monoaminergic hypothesis of depression, monoamine reuptake inhibitors have been developed as antidepressants and nowadays, they are used widely in clinical practice. However, these drugs have a limited efficacy and a slow onset of therapeutic action. Several strategies have been implemented to overcome these limitations, including switching to other drugs or introducing combined or augmentation therapies. In clinical practice, the most often used augmenting drugs are lithium, triiodothyronine, atypical antipsychotics, buspirone, and pindolol, although some others are in the pipeline. Moreover, multitarget antidepressants have been developed to improve efficacy. Despite the enormous effort exerted to improve these monoaminergic drugs, they still fail to produce a rapid and sustained antidepressant response in a substantial proportion of depressed patients. Recently, new compounds that target other neurotransmission system, such as the glutamatergic system, have become the focus of research into fast-acting antidepressant agents. These promising alternatives could represent a new pharmacological trend in the management of depression.

Deep brain stimulation electrode insertion and depression: Patterns of activity and modulation by analgesics.

BACKGROUND: An initial antidepressant effect when using deep brain stimulation (DBS) of the subcallosal area of the cingulate cortex (Cg25) to treat resistant depression that could be the result of electrode insertion has been described. We previously showed that electrode insertion into the infralimbic cortex (ILC; the Cg25 rodent correlate) provokes a temporally limited antidepressant-like effect that is counteracted by non-steroidal anti-inflammatory drugs, such as those routinely used for pain relief. OBJECTIVE: We characterized the effect of electrode insertion using functional neuroimaging and evaluated the impact of different analgesics on this effect. METHODS: The effect of electrode insertion into the ILC was evaluated by positron emission tomography. The effect of analgesics (ibuprofen, tramadol and morphine) on the behavioral effect induced by electrode insertion were evaluated through the forced swimming test and the novelty suppressed feeding test. Furthermore, glial fibrillary acidic protein (GFAP) and p11 expression were measured. RESULTS: Electrode implantation produces an antidepressant- and anxiolytic-like effect, a local decrease in glucose metabolism, and changes in several brain regions commonly related to depression and the antidepressant response. Ibuprofen counteracted the behavioral and molecular changes produced by electrode insertion (changes in GFAP and p11 protein expression). However, analgesics with no anti-inflammatory properties (e.g., tramadol) neither counteract the behavioral effects of electrode implantation nor the molecular mechanisms triggered. CONCLUSIONS: Analgesics without anti-inflammatory properties may not limit the transient benefit produced by electrode insertion reducing the time required to achieve remission in depressive DBS patients.

Involvement of 5-HT1A/1B receptors in the antinociceptive effect of paracetamol in the rat formalin test.

The mechanism of analgesic action of paracetamol (acetominophen) remains still unknown. However, a relationship between serotonergic system and the effect of paracetamol has been previously demonstrated. The serotonin activity in the brainstem is primarily under the control of 5-HT1A somatodendritic receptors, although some data also suggest the involvement of 5-HT1B receptors. To determine whether the 5-HT1A and 5-HT1B receptors are involved in the antinociceptive effect of paracetamol, we evaluated the effect of paracetamol (0.125-1 g/kg i.p.) followed by different antagonists [WAY 100,635 (0.8 mg/kg s.c.) and SB 216,641 (0.8 mg/kg s.c.)] or agonists [8-OH-DPAT (0.125 mg/kg s.c.) and CP 93,129 (0.125 mg/kg s.c.)] of 5-HT1A and 5-HT1B receptors, respectively, in the rat model of formalin-induced pain. We demonstrated that paracetamol administration showed a dose-dependent antinociceptive effect in the formalin test. WAY 100,635 (5-HT1A antagonist) induced an increase in the antinociceptive effect of paracetamol at 250 mg/kg doses. Conversely, 8-OH-DPAT (5-HT1A agonist) decreased the antinociceptive effect of paracetamol at 500-1000 mg/kg doses. However, SB216641 (5-HT1B antagonist) modified weakly the antinociceptive effect of paracetamol at 250 mg/kg doses and CP 93,129 (5-HT1B agonist) not produce a clear effect in the antinociceptive effect of paracetamol. These results suggest that the antinociceptive effect of paracetamol can be enhanced mainly by compounds having 5-HT1A antagonist properties in the formalin test and maybe by 5-HT1B receptors antagonists.

Understanding the different relationships between mood and sleep disorders in several groups of non-oncological patients with chronic pain.

OBJECTIVE: To compare sleep dimensions in patients suffering from chronic pain of different origins, and with a group of pain-free subjects. To analyze the relationship between depression and/or anxiety and sleep disorders in musculoskeletal, neuropathic, and fibromyalgia patients. METHODS: This cross-sectional study included patients diagnosed with neuropathic pain (NP) (n = 104), musculoskeletal pain (MSK) (n = 99), or fibromyalgia (FM) (n = 51), and pain free subjects (n = 72). Information about sleep dimensions (MOS-sleep), duration and intensity of pain (Visual Analog Scale), and anxiety and depression (Hospital Anxiety and Depression scale) was collected. RESULTS: Of the 254 patients with chronic pain (PCP) studied, the mean pain intensity was 6.6 (SD = 1.9), with an average duration of 9 years. The scores in all sleep dimensions of the MOS-sleep were higher in CPP (more disturbances) compared to pain free patients, and differences were observed among the three groups of PCP, with FM most severely affected. Anxiety (ß = 1.3), depression (ß = 1.1), intensity (ß = 1.7), and duration of pain (ß = 0.04) were associated with more sleep problems in MSK patients. In contrast, anxiety (ß = 2.5) and duration of pain (ß = 0.05) were negatively related to sleep in the NP patients, and only depression (ß = 1.3) affected FM patients. CONCLUSIONS: The sleep pattern differs among groups of PCP in the presence or absence of mood disorders. Understanding these disorders in each specific group of PCP is fundamental, and it can contribute to improve the clinical situation of the patients and better orientating therapeutic strategies.

Effects of S 38093, an antagonist/inverse agonist of histamine H3 receptors, in models of neuropathic pain in rats.

BACKGROUND: Histamine H3 receptors are mainly expressed on CNS neurons, particularly along the nociceptive pathways. The potential involvement of these receptors in pain processing has been suggested using H3 receptor inverse agonists. METHODS: The antinociceptive effect of S 38093, a novel inverse agonist of H3 receptors, has been evaluated in several neuropathic pain models in rat and compared with those of gabapentin and pregabalin. RESULTS: While S 38093 did not change vocalization thresholds to paw pressure in healthy rats, it exhibited a significant antihyperalgesic effect in the Streptozocin-induced diabetic (STZ) neuropathy model after acute and chronic administration and, in the chronic constriction injury (CCI) model only after chronic administration, submitted to the paw-pressure test. Acute S 38093 administration at all doses tested displayed a significant cold antiallodynic effect in a model of acute or repeated administration of oxaliplatin-induced neuropathy submitted to cold tail immersion, cold allodynia being the main side effect of oxaliplatin in patients. The effect of S 38093 increased following chronic administration (i.e. twice a day during 5 days) in the CCI and STZ models except in the oxaliplatin models where its effect was already maximal from the first administration The kinetics and size of effect of S 38093 were similar to gabapentin and/or pregabalin. Finally, the antinociceptive effect of S 38093 could be partially mediated by α2 adrenoreceptors desensitization in the locus coeruleus. CONCLUSIONS: These results highlight the interest of S 38093 to relieve neuropathic pain and warrant clinical trials especially in chemotherapeutic agent-induced neuropathic pain. SIGNIFICANCE: S 38093, a new H3 antagonist/inverse agonist, displays antiallodynic and antihyperalgesic effect in neuropathic pain, especially in oxaliplatin-induced neuropathy after chronic administration. This effect of S 38093 in neuropathic pain could be partly mediated by α2 receptors desensitization in the locus coeruleus.

Assessing the Construct Validity and Internal Reliability of the Screening Tool Test Your Memory in Patients with Chronic Pain.

Patients with chronic pain often complain about cognitive difficulties, and since these symptoms represent an additional source of suffering and distress, evaluating the cognitive status of these patients with valid and reliable tests should be an important part of their overall assessment. Although cognitive impairment is a critical characteristic of pain, there is no specific measure designed to detect these effects in this population. The objective was to analyze the psychometric properties of the "Test Your Memory" (TYM) test in patients with chronic pain of three different origins. A cross-sectional study was carried out on 72 subjects free of pain and 254 patients suffering from different types of chronic pain: neuropathic pain (104), musculoskeletal pain (99) and fibromyalgia (51). The construct validity of the TYM was assessed using the Mini-Mental State Examination (MMSE), Hospital Anxiety and Depression Scale (HADs), Index-9 from MOS-sleep, SF-12, and through the intensity (Visual Analogical Scale) and duration of pain. An exploratory factor analysis was also performed and internal reliability was assessed using Cronbach's alpha. After adjusting for potential confounders the TYM could distinguish between pain and pain-free patients, and it was correlated with the: MMSE (0.89, p<0.001); HAD-anxiety (-0.50, p<0.001) and HAD-depression scales (-0.52, p<0.001); MOS-sleep Index-9 (-0.49, p<0.001); and the physical (0.49, p < .001) and mental components (0.55, p < .001) of SF-12. The exploratory structure of the TYM showed an 8-factor solution that explained 53% of the variance, and Cronbach's alpha was 0.66. The TYM is a valid and reliable screening instrument to assess cognitive function in chronic pain patients that will be of particular value in clinical situations.

Are there different predictors of analgesic response between antidepressants and anticonvulsants in painful diabetic neuropathy?

BACKGROUND: To investigate baseline demographics and disease characteristics as predictors of the analgesic effect of duloxetine and pregabalin on diabetic peripheral neuropathic pain (DPNP). METHODS: Based on data from the COMBO-DN study, a multinational clinical trial in DPNP, the potential impact of baseline characteristics on pain relief after 8-week monotherapy with 60 mg/day duloxetine or 300 mg/day pregabalin was assessed using analyses of covariance. Subgroups of interest were characterized regarding their baseline characteristics and efficacy outcomes. RESULTS: A total of 804 patients were evaluated at baseline. A significant interaction with treatment was observed in the mood symptom subgroups with a larger pain reduction in duloxetine-treated patients having no mood symptoms [Hospital Anxiety and Depression Scale (HADS) depression or anxiety subscale score <11; -2.33 (duloxetine); -1.52 (pregabalin); p = 0.024]. There were no significant interactions between treatment for subgroups by age (<65 or ≥65 years), gender, baseline pain severity [Brief Pain Inventory Modified Short Form (BPI-MSF) average pain <6 or ≥6], diabetic neuropathy duration (≤2 or >2 years), baseline haemoglobin A1c (HbA1c) (<8% or ≥8%), presence of comorbidities and concomitant medication use. CONCLUSIONS: Our analyses suggest that the efficacy of duloxetine and pregabalin for initial 8-week treatment in DPNP was consistent across examined subgroups based on demographics and disease characteristics at baseline except for the presence of mood symptoms. Duloxetine treatment appeared to be particularly beneficial in DPNP patients having no mood symptoms.

Early responses to deep brain stimulation in depression are modulated by anti-inflammatory drugs.

Deep brain stimulation (DBS) in the subgenual cingulated gyrus (SCG) is a promising new technique that may provide sustained remission in resistant major depressive disorder (MDD). Initial studies reported a significant early improvement in patients, followed by a decline within the first month of treatment, an unexpected phenomenon attributed to potential placebo effects or a physiological response to probe insertion that remains poorly understood. Here we characterized the behavioural antidepressant-like effect of DBS in the rat medial prefrontal cortex, focusing on modifications to rodent SCG correlate (prelimbic and infralimbic (IL) cortex). In addition, we evaluated the early outcome of DBS in the SCG of eight patients with resistant MDD involved in a clinical trial. We found similar antidepressant-like effects in rats implanted with electrodes, irrespective of whether they received electrical brain stimulation or not. This effect was due to regional inflammation, as it was temporally correlated with an increase of glial-fibrillary-acidic-protein immunoreactivity, and it was blocked by anti-inflammatory drugs. Indeed, inflammatory mediators and neuronal p11 expression also changed. Furthermore, a retrospective study indicated that the early response of MDD patients subjected to DBS was poorer when they received anti-inflammatory drugs. Our study demonstrates that electrode implantation up to the IL cortex is sufficient to produce an antidepressant-like effect of a similar magnitude to that observed in rats receiving brain stimulation. Moreover, both preclinical and clinical findings suggest that the use of anti-inflammatory drugs after electrode implantation may attenuate the early anti-depressive response in patients who are subjected to DBS.

Unexplained pain complaints and depression in older people in primary care.

OBJECTIVE: Chronic pain and depression are frequent conditions in primary care patients. Depression is frequently overlooked in the presence of pain of uncertain origin. The aim is to measure the prevalence and clinical correlates of unrecognized comorbid mood disorders and chronic pain of uncertain origin in older primary care patients, and to elucidate the differences with younger adults with the same conditions. DESIGN: Cross-sectional study. SETTING: Primary care centres in Spain. PARTICIPANTS: Patients (n= 2720) with persistent pain of uncertain origin. MEASUREMENTS: Pain characteristics, sites and intensity (Visual Analogical Scales), depression (PRIME-MD interview), clinical characteristics and health services use. RESULTS: We observed a similarly high (80.5%) prevalence of undiagnosed mood disorders (especially major depressive disorders) among older and younger adult patients with comorbid chronic pain complaints of uncertain origin. Older patients suffered pain that was more intense, longer lasting and located in a higher number of different areas, when compared to younger patients. Pain intensity was a factor associated with suffering from mood disorders among patients above 65 years, whilst the number of pain sites was a more important factor among younger patients. CONCLUSIONS: Depression is highly associated with pain of uncertain origin in older patients with differences in pain characteristics when compared to younger patients. The robust comorbid relationship between both conditions should alert clinicians to specifically look for depression in the presence of poorly explained painful symptoms.

Behavioral, neurochemical and morphological changes induced by the overexpression of munc18-1a in brain of mice: relevance to schizophrenia.

Overexpression of the mammalian homolog of the unc-18 gene (munc18-1) has been described in the brain of subjects with schizophrenia. Munc18-1 protein is involved in membrane fusion processes, exocytosis and neurotransmitter release. A transgenic mouse strain that overexpresses the protein isoform munc18-1a in the brain was characterized. This animal displays several schizophrenia-related behaviors, supersensitivity to hallucinogenic drugs and deficits in prepulse inhibition that reverse after antipsychotic treatment. Relevant brain areas (that is, cortex and striatum) exhibit reduced expression of dopamine D(1) receptors and dopamine transporters together with enhanced amphetamine-induced in vivo dopamine release. Magnetic resonance imaging demonstrates decreased gray matter volume in the transgenic animal. In conclusion, the mouse overexpressing brain munc18-1a represents a new valid animal model that resembles functional and structural abnormalities in patients with schizophrenia. The animal could provide valuable insights into phenotypic aspects of this psychiatric disorder.

High prevalence of confirmed, but also of potential and believed, neuropathic pain in pain clinics.

BACKGROUND AND AIMS: Epidemiological data about neuropathic pain are still scarce. A national survey, based on neurologic clinical diagnosis, was performed to determine its prevalence among patients attending pain clinics. METHODS: An epidemiological cross-sectional study involving pain clinics across all regions in Spain was carried out. Pain specialists evaluated the medical files and the clinical condition of patients attending their practices systematically during 1 day. They used the revised definition and grading system proposed in 2008 to decide whether a given patient had definite (i.e., confirmed), probable (potential) or possible (believed) neuropathic pain. Also, they provided a diagnostic label for neuropathic pain conditions and appraised treatment adequacy. RESULTS: In a single day, 178 pain specialists provided data from 2173 patients. Definite, probable and possible neuropathic pain was cited in 639 (29.4%), 304 (14.0%) and 97 (4.5%) patients, respectively. Almost two-thirds of these were women. A diagnostic label of primary pure central and/or peripheral neuropathic pain was cited in 344 (15.8%) patients. The most common diagnostic label (568 patients) was low back pain or sciatica causing mixed neuropathic pain. Definite neuropathic pain diagnosis was less likely in patients with mixed pain conditions and in women derived from primary care. Co-morbid depressive or anxiety symptoms were usual. CONCLUSIONS: Definite (confirmed) neuropathic pain alone was as prevalent as neuropathic pain ascertained with screening questionnaires in prior recent European studies. The clinical relevance of the surplus of patients with potential and believed neuropathic pain ascertained by clinicians is uncertain.

Extracellular signal-regulated kinase activation in the chronic constriction injury model of neuropathic pain in anaesthetized rats.

BACKGROUND: The role of extracellular signal-regulated kinases (ERKs) in nociception has been explored in the last years. While in spinal cord their activation is frequently correlated with pain or acute noxious stimuli, supraspinally, this association is not so evident and remains unclear. This study aims to evaluate ERK1/2 activation in the spinal cord and brainstem nuclei upon neuropathy and/or an additional mechanical stimulus. METHODS: Acute noxious mechanical stimulation was applied in the left hindpaw of anaesthetized SHAM-operated and chronic constriction injured (CCI, neuropathic pain model) rats. Other SHAM or CCI rats did not receive any stimulus. Immunohistochemistry against the phosphorylated isoforms of ERK1/2 (pERK1/2) was performed in lumbar spinal cord and brainstem sections to assess ERK1/2 activation. RESULTS: In the spinal cord, stimulation promoted an increase in pERK1/2 expression in the superficial dorsal horn of SHAM rats. No significant effects were caused by CCI alone. At supraspinal level, changes in ERK1/2 activation induced by CCI were observed in A5, locus coeruleus (LC), raphe obscurus (ROb), raphe magnus, dorsal raphe (DRN), lateral reticular and paragigantocellularis nucleus. CCI increased pERK1/2 expression in all these nuclei, with exception of LC, where a significant decrease was verified. Mechanical noxious stimulation of CCI rats decreased pERK1/2 expression in ROb and DRN, but no further changes were detected in either SHAM- or CCI-stimulated animals. CONCLUSION: ERK1/2 are differentially activated in the spinal cord and in selected brainstem nuclei implicated in nociception, in response to an acute noxious stimulus and/or to a neuropathic pain condition.

L-DOPA modifies the antidepressant-like effects of reboxetine and fluoxetine in rats.

Nowadays the most widely used antidepressants are selective serotonin reuptake inhibitors (SSRI) or noradrenaline reuptake inhibitors (NRI), however, these take four to eight weeks to exert their effects and each drug is efficacious only in 60-70% of patients. In an attempt to improve the efficacy of antidepressants, new drugs that also modify dopamine levels are being developed. The aim of this study was to investigate the impact of l-DOPA administration on the effect elicited by antidepressants on serotonergic and noradrenergic neurotransmission. To this end, single-unit extracellular recordings of the noradrenergic nucleus, locus coeruleus (LC), and the serotonergic nucleus, dorsal raphe (DRN) combined with behavioural approaches were performed. l-DOPA did not modify the basal neuronal activity in either the LC or the DRN or induce any change in the modified forced swimming test. However, l-DOPA enhanced the neuronal response to reboxetine in the LC and increased its antidepressant-like effects but counteracted the effect of fluoxetine on neurons in the LC and decreased its antidepressant-like effect. The sensitivity of neurons in the DRN to reboxetine and fluoxetine was not altered by the administration of l-DOPA. Taken together, these results indicate that l-DOPA modifies the effect of SSRI and NRI antidepressants in opposing ways.

Noradrenalina y opioides se dan la mano en analgesia / No disponible

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Pain as a symptom of depression: prevalence and clinical correlates in patients attending psychiatric clinics.

BACKGROUND: The need to assess the prevalence and characteristics of painful symptoms among depressed patients attended by psychiatrists in their regular clinical practice. METHODS: A multi-centre, cross-sectional study was carried out in a large sample (n=3566) of patients attending out-patient psychiatric facilities in Spain. All types of DSM-IV-TR depressive disorders were included. Data on the diagnosis, specific symptoms, intensity of depression and antidepressant and analgesic drug treatments were collected. The presence and characteristics of significant pain (visual analogue scale score>40) at the time of the study were also recorded. RESULTS: The prevalence of pain in depressed patients was 59.1% (CI 95%: 57.7%; 60.7%). Factors associated independently with the existence of significant pain were: being female, presence of loss of energy and the diagnosis of dysthymia or depression induced by physical disorders. In addition, age and the intensity of depression were two risk factors, where each year of age and each point in the Hamilton scale increased the risk of having pain by 2% and 8% respectively. The presence of anhedonia and the diagnosis of depression induced by illegal drugs were factors inversely related to pain. LIMITATIONS: The cross-sectional naturalistic characteristics of the study. CONCLUSION: Our data show a high prevalence of pain among depressive patients attending psychiatric clinics. Painful symptoms are modulated differently depending on the type of depression and the presence of specific symptoms, such as loss of energy or anhedonia. Psychiatrists should ask their depressive patients for the presence of pain on a regular basis.

Neurobiological bases of quetiapine antidepresant effect in the bipolar disorder.

Bipolar disorder is considered an important public health problem in the world. The depressive phase is the most important in terms of frequency, duration, and impairment of the quality of life. Common treatment of bipolar depression usually includes antidepressants, mood stabilizers and antipsychotics in different combinations, despite not having a specific indication for that. Quetiapine is the first drug in Europe that has obtained a specific indication for the treatment of bipolar depression, due to a pharmacologic profile that makes it to act on the three neurotransmitter systems involved in bipolar depression neurobiology. Regarding the dopaminergic pathway, quetiapine leads to an increasing of prefrontal dopamine release by antagonism of5-HT2A receptors, partial agonist of 5-HT1A and antagonism of a2 adrenoceptors. Quetiapine also enhances the serotoninergic transmission by increasing the density of receptors5-HT1A in the prefrontal cortex and by antagonism of 5-HT2A receptors and a2 adrenoceptors. On the other hand, norquetiapine, the main active metabolite of quetiapine, actsas a 5-HT2C antagonist and is a potent inhibitor of norepinephrine transporter (NET). NET inhibition leads to an increase of noerpinephrine in the synapse, and together with the increase of prefrontal dopamine and serotonin, could explain the antidepressive effect demonstrated by quetiapine in several clinical trials. Quetiapine's action on glutamatergicand GABAergic receptors represents an interesting object of research, together with a potential neuroprotective effect that have already been observed in animal models.

The role of age in the development of Schneiderian symptoms in patients with a first psychotic episode.

OBJECTIVE: The likelihood of developing psychotic symptoms greatly increases after puberty. In acute psychotic disorders, first rank symptoms (FRS) are prevalent and considered useful for the diagnostic process. The aim of this study was to test for a linear association between age and the probability of occurrence of FRS in patients with a first psychotic episode (FPE). METHOD: A total of 112 patients, consecutively admitted with an FPE, were included at baseline and evaluated yearly over a 3-year period using SCID-I and a checklist of 11 items of FRS. RESULTS: FRS were documented for 65.2% patients at baseline. There was a dose-response relationship in the association between age and FRS. There was no interaction with sex or with final diagnostic category. CONCLUSION: Variation in the expression of the core positive symptoms of psychosis is subject to the influence of underlying age-dependent maturational processes both in terms of occurrence and level of severity.

Antidepresivos: ¿cuándo son analgésicos y cuándo antidepresivos? / Antidepressant: where are they analgesics or antidepresant drugs?

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