Surgical repair of Salter-Harris type II fracture of the distal humerus: short and long-term outcomes in a case series of three dogs and one cat.

CASE HISTORIES: Three dogs and one cat sustained forelimb trauma and were presented to a university veterinary clinic (Liège, Belgium) and a private veterinary hospital (Beacouzé, France). All four animals were referred for surgery. CLINICAL FINDINGS: Two dogs and the cat were ambulatory on admission but unable to bear weight on the affected limb. One dog was non-ambulatory and lacked voluntary movement and sensation in one forelimb. Salter-Harris type II fractures of the distal humerus were diagnosed by radiography in all cases; avulsion of the brachial plexus and pelvic fractures were also present in the non-ambulatory dog. TREATMENT AND OUTCOME: All Salter-Harris type II fractures were stabilised by open reduction and internal fixation with cross pins. One minor complication (seroma) and three major complications (implant migration) developed after surgery. The pins were completely removed in one case and partially removed in two cases to resolve these complications. At the final follow-up examination (12-31 months after surgery), owners reported no lameness in three of the four cases and grade 2/5 left forelimb lameness in one case. CLINICAL RELEVANCE: This type of fracture is rarely described in the literature; however, it should be included in the differential diagnoses of traumatic humeral fractures in growing dogs and cats. In this case series, we achieved fair-to-excellent short-term and long-term outcomes after osteosynthesis of Salter-Harris type II fractures by cross pinning.

Osteochondritis dissecans of the vertebral endplate of C5 with concomitant C4-C5 disc protrusion in a French Bulldog.

A 4-year-old French bulldog was presented with neck pain and left forelimb lameness. CT scan revealed a bony defect in the craniodorsal rim of the endplate of C5 with a concomitant disc protrusion leading to ventral spinal cord compression. Ventral slot at C4-C5 was performed to remove the protruding material and the fragment. Based on CT and histological findings, this bone defect was consistent with osteochondritis dissecans. Neck pain was absent immediately after the operation and the dog recovered without complication. Only a slight proprioceptive deficit of the left forelimb persisted during the 6-month of follow-up. Based on our search of the veterinary literature, this is the first published report of an osteochondritis dissecans of cervical endplate treated surgically.

Laryngeal paralysis secondary to cervical bite injuries in five dogs.

CASE HISTORIES: Medical records of a veterinary hospital in Belgium were reviewed for dogs (n = 5) that presented between 2016 and 2019 with laryngeal paralysis secondary to bite wounds to the cervical region received while fighting with other dogs. The time elapsed between the trauma and presentation was from a few hours up to 5 days. CLINICAL FINDINGS AND TREATMENT: Bilateral laryngeal paralysis was identified in three dogs and unilateral laryngeal paralysis in two dogs via endoscopic assessment of laryngeal function. The primary concomitant lesions included tracheal injury in 3/5 dogs and oesophageal injury in 1/5 dogs. One dog with bilateral laryngeal paralysis was treated medically as no signs of dyspnoea were present. Surgical management was elected in 4/5 dogs based on evaluation of their clinical status and lesions revealed by endoscopic examination of upper gastrointestinal and respiratory tracts. Dogs underwent surgical procedures that were determined to be appropriate for treatment of the lesions identified on clinical examination, diagnostic imaging, and endoscopy. The cervical region was explored through a ventral midline approach in 2/4 cases, to close tracheal perforations. Temporary tracheostomy was performed in 2/4 cases. Procedures to correct brachycephalic airway obstructive syndrome were performed in 2/4 cases. Cricoarytenoid lateralisation was performed in 2/4 dogs. Dogs were hospitalised for 2-10 days and received antimicrobial therapy before surgery and for 2-3 weeks after surgery. Physical examination and respiratory function were normal in 3/5 dogs 4-6 months after discharge. Information regarding outcomes for two cases was obtained from the owners by telephone assessment 1-6 months after surgery. The owner of each dog reported the respiratory function to be excellent. DIAGNOSIS: Uni- or bilateral, transient or permanent laryngeal paralysis with concomitant oesophageal, tracheal, or laryngeal lesions following cervical dog bite injuries diagnosed by endoscopic examination of upper gastrointestinal and respiratory tracts. CLINICAL RELEVANCE: This case series describes the diagnosis and management of dogs with laryngeal paralysis secondary to cervical dog bite injuries. To the authors' knowledge, this is the first published report documenting bilateral laryngeal paralysis secondary to cervical dog bite injuries. Clinicians should be aware of this pathology and the importance of investigating laryngeal function in dogs presenting with cervical bites, particularly those with inspiratory dyspnoea. Upper airway and digestive endoscopy are recommended for complete assessment of cervical traumatic injuries.

Leiomyoma in the nasal cavity of a dog.

A 7-year-old, 34-kg, neutered male Labrador retriever was presented with a 1-year history of intermittent sneezing with occasional left-sided epistaxis. CT revealed a mass in the left nasal cavity. Histopathological analysis of rhinoscopy-guided tissue biopsies was consistent with chronic necrotic and ulcerative rhinitis. Surgical debridement by ventral rhinotomy was subsequently performed and histopathological diagnosis was leiomyoma. Complete resolution of the nasal discharge and reduced sneezing frequency were observed after surgery. Fourteen months postoperatively, CT detected no regrowth of the mass.

Differential innervation of superficial versus deep laminae of the dorsal horn by bulbo-spinal serotonergic pathways in the rat.

Convergent data showed that bulbo-spinal serotonergic projections exert complex modulatory influences on nociceptive signaling within the dorsal horn. These neurons are located in the B3 area which comprises the median raphe magnus (RMg) and the lateral paragigantocellular reticular (LPGi) nuclei. Because LPGi 5-HT neurons differ from RMg 5-HT neurons regarding both their respective electrophysiological properties and responses to noxious stimuli, we used anatomical approaches for further characterization of the respective spinal projections of LPGi versus RMg 5-HT neuron subgroups. Adult Sprague-Dawley rats were stereotaxically injected into the RMg or the LPGi with the anterograde tracer Phaseolus vulgaris leucoagglutinin (PHA-L). The precise location of injection sites and RMg vs LPGi spinal projections into the different dorsal horn laminae were visualized by PHA-L immunolabeling. Double immunofluorescent labeling of PHA-L and the serotonin transporter (5-HTT) allowed detection of serotonergic fibers among bulbo-spinal projections. Anterograde tracing showed that RMg neurons project preferentially into the deep laminae V-VI whereas LPGi neuron projections are confined to the superficial laminae I-II of the ipsilateral dorsal horn. All along the spinal cord, double-labeled PHA-L/5-HTT immunoreactive fibers, which represent only 5-15% of all PHA-L-immunoreactive projections, exhibit the same differential locations depending on their origin in the RMg versus the LPGi. The clear-cut distinction between dorsal horn laminae receiving bulbo-spinal serotonergic projections from the RMg versus the LPGi provides further anatomical support to the idea that the descending serotonergic pathways issued from these two bulbar nuclei might exert different modulatory influences on the spinal relay of pain signaling neuronal pathways.

MDCT of interatrial septum.

ECG-gated cardiac multidetector row computed tomography (MDCT) allows precise analysis of the interatrial septum (IAS). This pictorial review provides a detailed description of the normal anatomy, variants and abnormalities of the IAS such as patent foramen ovale, congenital abnormalities such as atrial septal defects as well as tumors and tumoral-like processes that develop on the IAS.

High on-treatment platelet reactivity with ticagrelor versus prasugrel: a systematic review and meta-analysis.

BACKGROUND: Ticagrelor and prasugrel have shown superiority over clopidogrel. However, it remains unclear if one is superior to another regarding on-treatment platelet reactivity. OBJECTIVES: To compare the impact of ticagrelor and prasugrel on high on-treatment platelet reactivity (HTPR). METHODS: The PubMed and Cochrane databases were searched for eligible studies in December 2014. Studies were eligible if they compared ticagrelor and prasugrel regarding high on-treatment platelet reactivity (HTPR). Pooled estimates were calculated by using a random-effects model with 95% confidence intervals. RESULTS: We included 14 studies and 1822 patients: 805 and 1017 in the ticagrelor and prasugrel groups, respectively. The rate of HTPR was significantly lower in the ticagrelor group: 1.5% vs. 9.8% (RR = 0.27 [0.14-0.50]). The pre-specified analysis focusing on randomized trials (n = 10) showed consistent results (RR = 0.27 [0.12-0.60]). CONCLUSION: Our results suggest that ticagrelor allows a higher platelet reactivity inhibition as compared with prasugrel and leads to a further decrease in the rate of HTPR.

Altered nociception in mice with genetically induced hypoglutamatergic tone.

Extensive pharmacological evidence supports the idea that glutamate plays a key role in both acute and chronic pain. In the present study, we investigated the implication of the excitatory amino acid in physiological nociception by using mutant mice deficient in phosphate-activated glutaminase type 1 (GLS1), the enzyme that synthesizes glutamate in central glutamatergic neurons. Because homozygous GLS1-/- mutants die shortly after birth, assays for assessing mechanical, thermal and chemical (formalin) nociception were performed on heterozygous GLS1+/- mutants, which present a clear-cut decrease in glutamate synthesis in central neurons. As compared to paired wild-type mice, adult male GLS1+/- mutants showed decreased responsiveness to mechanical (von Frey filament and tail-pressure, but not tail-clip, tests) and thermal (Hargreaves' plantar, tail-immersion and hot-plate tests) nociceptive stimuli. Genotype-related differences were also found in the formalin test for which GLS1+/- mice exhibited marked decreases in the nociceptive responses (hindlimb lift, lick and flinch) during both phase 1 (0-5 min) and phase 2 (16-45 min) after formalin injection. On the other hand, acute treatment with memantine (1mg/kg i.p.), an uncompetitive antagonist at NMDA glutamate receptors, reduced nociception responses in wild-type but not GLS1+/- mice. Conversely, antinociceptive response to acute administration of a low dose (1mg/kg s.c.) of morphine was significantly larger in GLS1+/- mutants versus wild-type mice. Our findings indicate that genetically driven hypoactivity of central glutamatergic neurotransmission renders mice hyposensitive to nociceptive stimulations, and promotes morphine antinociception, further emphasizing the critical role of glutamate in physiological nociception and its opioid-mediated control.

CGRP receptor blockade by MK-8825 alleviates allodynia in infraorbital nerve-ligated rats.

BACKGROUND: Previous data showed that, in rats, anti-migraine drugs (triptans, olcegepant) significantly reduced mechanical allodynia induced by infraorbital nerve (ION) ligation but not that evoked by sciatic nerve (SN) ligation. Whether this also occurs with MK-8825, a novel anti-migraine drug also acting through CGRP receptor blockade (but chemically unrelated to olcegepant) was tested in the present study, which also investigated possible anti-neuroinflammatory effects of this drug. METHODS: Adult male Sprague-Dawley rats underwent unilateral chronic constriction injury (CCI) to either the ION or the SN, and mechanical allodynia was assessed 2 weeks later within the ipsilateral vibrissae territory or hindpaw, respectively. Transcripts of neuroinflammatory markers were quantified by real-time quantitative RT-PCR in ipsilateral trigeminal ganglion and spinal trigeminal nucleus in CCI-ION rats. RESULTS: Acute as well as repeated (for 4 days) administration of MK-8825 (30-100 mg/kg, i.p.) significantly reduced CCI-ION-induced mechanical allodynia but was ineffective in CCI-SN rats. CCI-ION was associated with marked up-regulation of neuronal and glial inflammatory markers (ATF3, IL6, iNOS, COX2) in ipsilateral trigeminal ganglion but not spinal trigeminal nucleus. MK-8825-induced inhibition of iNOS mRNA up-regulation probably underlay its anti-allodynic effect because pharmacological blockade of iNOS by AMT (6 mg/kg, s.c.) mimicked this effect. CONCLUSIONS: These data further support the idea that CGRP receptor blockade might be a valuable approach to alleviate trigeminal, but not spinal, neuropathic pain through, at least partly, an inhibitory effect on neuropathic pain-associated increase in NO production in trigeminal ganglion.

Ethanol-induced epigenetic regulations at the Bdnf gene in C57BL/6J mice.

High ethanol intake is well known to induce both anxiolytic and anxiogenic effects, in correlation with chromatin remodeling in the amygdaloid brain region and deficits in cell proliferation and survival in the hippocampus of rodents. Whether only moderate but chronic ethanol intake in C57BL/6J mice could also have an impact on chromatin remodeling and neuroplasticity was addressed here. Chronic ethanol consumption in a free choice paradigm was found to induce marked changes in the expression of genes implicated in neural development and histone post-translational modifications in the mouse hippocampus. Transcripts encoding neural bHLH activators and those from Bdnf exons II, III and VI were upregulated, whereas those from Bdnf exon VIII and Hdacs were downregulated by ethanol compared with water consumption. These ethanol-induced changes were associated with enrichment in both acetylated H3 at Bdnf promoter PVI and trimethylated H3 at PII and PIII. Conversely, acetylated H3 at PIII and PVIII and trimethylated H3 at PVIII were decreased in ethanol-exposed mice. In parallel, hippocampal brain-derived neurotrophic factor (BDNF) levels and TrkB-mediated neurogenesis in the dentate gyrus were significantly enhanced by ethanol consumption. These results suggest that, in C57BL/6J mice, chronic and moderate ethanol intake produces marked epigenetic changes underlying BDNF overexpression and downstream hippocampal neurogenesis.

Bivalirudin use in patients undergoing percutaneous coronary intervention for acute myocardial infarction. Insights from the prospective, multi-centre EUROVISION registry.

BACKGROUND: The effectiveness of bivalirudin in patients undergoing percutaneous coronary intervention for acute myocardial infarction has been tested in clinical trials, but its use in a real-world scenario has never been reported. METHODS: From the total number of patients enrolled in the EUROVISION registry, 678 subjects affected by ST-elevation myocardial infarction were selected and included in the analysis. Posology and usage patterns of bivalirudin, as evaluated by dose and time of drug bolus and infusion administered, were evaluated. The 30-day outcome has been assessed by efficacy and safety endpoints. RESULTS: All patients received an initial intravenous bolus of bivalirudin (0.70±0.25 mg/kg) followed by an infusion (1.58±0.47 mg/kg/h; duration: 60 [30, 107] min) in 99.3% of cases. An additional bolus (0.49±0.06 mg/kg) was administered in 9.3% of patients. Bivalirudin infusion was prolonged after procedure in 62.2%. Death occurred in 2.1% of patients, non-fatal myocardial reinfarction in 0.3%, unplanned revascularization in 0.6% and non-fatal stroke in 0.4%. Acute stent thrombosis was not observed. Major bleeding occurred in 1.5% of patients. CONCLUSIONS: Bivalirudin usage in the setting of primary PCI provided excellent results in terms of 30-day outcome even in a real-world population.

Safety of intravenous ivabradine in acute ST-segment elevation myocardial infarction patients treated with primary percutaneous coronary intervention: a randomized, placebo-controlled, double-blind, pilot study.

AIMS: Rapid heart rate lowering may be attractive in acute ST-segment elevation myocardial infarction (STEMI). Accordingly we studied the effect of intravenous ivabradine on heart rate in this setting. METHODS AND RESULTS: This was a multicenter randomized double-blind placebo-controlled trial: patients aged 40-80 years were randomized after successful primary percutaneous coronary intervention (PCI) performed within 6 h of STEMI symptom onset. Patients were in sinus rhythm and with heart rate >80 bpm and systolic blood pressure >90 mm Hg. They were randomly assigned (2:1 ratio) to intravenous ivabradine (n=82) (5 mg bolus over 30 s, followed by 5 mg infusion over 8 h) or matching placebo (n=42). The primary outcome measure was heart rate and blood pressure. In both groups, heart rate was reduced over 8 h, with a faster and more marked decrease on ivabradine than placebo (22.2 ± 1.3 vs 8.9 ± 1.8 bpm, p<0.0001). After treatment discontinuation, heart rate was similar in both groups. Throughout the study, there was no difference in blood pressure between groups. There was no difference in cardiac biomarkers (creatine kinase (CK-MB), troponin T and troponin I). On echocardiography performed at baseline and post treatment (median 1.16 days), final left ventricular volumes were lower in the ivabradine group both for left ventricular end-diastolic volume (LVEDV) (87.1 ± 28.2 vs 117.8 ± 21.4 ml, p=0.01) and left ventricular end-systolic volume (LVESV) (42.5 ± 19.0 versus 59.1 ± 11.3 ml, p=0.03) without differences in volume change or left ventricular ejection fraction. CONCLUSION: This pilot study shows that intravenous ivabradine may be used safely to slow the heart rate in STEMI. Further studies are needed to characterize its effect on infarct size, left ventricular function and clinical outcomes in this population.

Aspergillus vertebral osteomyelitis in immunocompetent subjects: case report and review of the literature.

Aspergillus spondylodiscitis (AS) is rare in immunocompetent (IC) patients. A 65-year-old diabetic IC male subject presented with cervical AS 18 months after otomycosis. Two serological tests, mastoidectomy and biopsy of the sphenoid bone, were negative. A prevertebral biopsy identified A. flavus. The patient was successfully treated with voriconazole. Forty-three cases of AS in IC patients have been published. A predisposition was found in 84 % of cases. Fever was reported in 20 % of cases, whereas neurological defects were present in 41 %. Serology was inconsistently positive (5/7) and diagnosis was confirmed by biopsy or surgery. A. fumigatus was the most frequently isolated species (74 %). All episodes were medically treated, associated with surgery in 57 % of cases, and 73 % of patients fully recovered. AS must be discussed in IC patients presenting with risk factors, including diabetes mellitus. Biopsy is necessary to confirm diagnosis, since serology offers low sensitivity. Nevertheless, the prognosis is good.

5-HT(1A) receptors direct the orientation of plasticity in layer 5 pyramidal neurons of the mouse prefrontal cortex.

Several psychiatric disorders involving the prefrontal cortex (PFC) are associated with a dysfunction of 5-HT(1A) receptors (5-HT(1A)R). These receptors, located on interneurons and pyramidal neurons, may influence neuronal excitability through a regulation of the balance between excitation (E) and inhibition (I). Patch-clamp recordings in mouse cortical slices were performed to determine the modulatory role of 5-HT(1A)R on the excitability and the synaptic plasticity of layer 5 pyramidal neurons (L5PyNs) of the PFC. This was done by a comparison of postsynaptic currents evoked by electrical stimulation in layer 2/3 of 5-HT(1A)R-KO and wild-type (WT) mice. We observed that the E-I balance was significantly changed from 20% E-80% I in WT mice to 23% E-77% I in 5-HT(1A)R-KO mice, demonstrating that 5-HT(1A)Rs contribute to the control of the balance between excitation and inhibition. Furthermore, we show that interfering with 5-HT(1A)R reduced the magnitude of the long term potentiation of excitation (eLTP) (induced by high frequency stimulation). In addition, we show that 5-HT(1A)Rs determine the orientation of the synaptic plasticity towards LTP or LTD or no plasticity through the modulation of NMDAR-mediated currents. Our data point out to a unique role of 5-HT(1A) postsynaptic receptors in PFC to adapt the functional plasticity of L5PyNs towards LTP, LTD or no plasticity. This brings a new way to intervene on neuronal networks of the PFC in anxiety disorders and schizophrenia.

Effects of tapentadol on mechanical hypersensitivity in rats with ligatures of the infraorbital nerve versus the sciatic nerve.

BACKGROUND: Convergent data showed that neuropathic pain has specific characteristics at cephalic versus extra-cephalic level, where single-targeted drugs differentially alleviate pain. Because the novel analgesic drug, tapentadol, is acting at two targets, µ-opioid receptors (as agonist) and noradrenaline reuptake (as inhibitor), we tested its effects on neuropathic pain at both cephalic and extra-cephalic levels. METHODS: Sprague-Dawley rats underwent unilateral constriction injury (CCI) to the infraorbital nerve (ION; cephalic territory) or the sciatic nerve (SN; extra-cephalic territory), and alleviation of nerve lesion-induced mechanical allodynia/hyperalgesia was assessed after acute or repeated (for 4 days) treatment with tapentadol compared with morphine and/or reboxetine (noradrenaline reuptake inhibitor) 2 weeks after surgery. Possible changes in the expression of the neuroinflammatory markers activating transcription factor 3 (ATF3), interleukin-6 (IL-6) and brain-derived neurotrophic factor (BDNF) by repeated tapentadol treatment were quantified by real-time reverse transcription polymerase chain reaction in ganglia and central tissues. RESULTS: Acute administration of tapentadol (1-10 mg/kg, i.p.) significantly reduced allodynia in both CCI-SN and CCI-ION rats. Although morphine (3 mg/kg, s.c.) or reboxetine (10 mg/kg, i.p.) alone was only marginally active, the combination of both drugs produced supra-additive effects like those observed with tapentadol. In contrast to repeated morphine whose effects vanished, the anti-allodynic effects of tapentadol remained unchanged after a 4-day treatment. However, the latter treatment with tapentadol did not affect nerve lesion-evoked overexpression of ATF3, IL-6 and BDNF transcripts. CONCLUSIONS: The dual synergistic pharmacological properties of tapentadol, which result in clear-cut anti-neuropathic pain effects at both cephalic and extra-cephalic levels, probably involve mechanisms downstream of nerve injury-induced neuroinflammatory reaction.

RNA splicing and editing modulation of 5-HT(2C) receptor function: relevance to anxiety and aggression in VGV mice.

Changes in serotonin(2C) receptor (5-HTR2c) editing, splicing and density were found in conditions such as depression and suicide, but mechanisms explaining the changes in 5-HTR2c function are unknown. Thus, mice expressing only the fully edited VGV isoform of 5-HTR2c, in which clinically relevant behavioral changes are associated with alterations in splicing and receptor density, were studied. VGV mice displayed enhanced anxiety-like behavior in response to a preferential 5-HTR2c agonist in the social interaction test. Nearly half of interactions between pairs of VGV congeners consisted of fighting behaviors, whereas no fighting occurred in wild-type (WT) mice. VGV mice also exhibited a striking increase in freezing behaviors in reaction to an innately aversive ultrasonic stimulus. This behavioral phenotype occurred in conjunction with decreased brain 5-HT turnover during stress. These functional data were put in relation with the 5-HTR2c mRNA splicing process generating a truncated protein (5-HTR2c-Tr) in addition to the full-length receptor (5-HTR2c-Fl). 5-HTR2c-Tr mRNA was less abundant in many brain regions of VGV mice, which concomitantly had more 5-HTR2c than WT mice. Fluorescence resonance energy transfer and bioluminescence resonance energy transfer studies in transfected living HEK293T cells showed that 5-HTR2c-Tr interacts with 5-HTR2c-Fl. The 5-HTR2c-Tr was localized in the endoplasmic reticulum where it retained 5-HTR2c-Fl, preventing the latter to reach the plasma membrane. Consequently, 5-HTR2c-Tr decreased (3)H-mesulergine binding to 5-HTR2c-Fl at the plasma membrane in a concentration-dependent manner and more strongly with edited 5-HTR2c-Fl. These results suggest that 5-HTR2c pre-mRNA editing and splicing are entwined processes determining increased 5-HTR2c levels in pathological conditions through a deficit in 5-HTR2c-Tr.

Beware of suboptimal medical management of patients with atherosclerosis requiring revascularization.

AIM: The aim of this paper was to assess a daily-life evaluation of vascular risk factor control, pharmacological treatment and prognosis in patients with atherosclerosis referred for revascularization. METHODS: Prospective observational study conducted in a French University Hospital with collection of atherosclerosis referral site information, reported patient history, documented atherosclerosis sites seen on examination, biological data, and clinical outcomes. RESULTS: 956 patients (82.6% men, 64.5±10.1 years) were enrolled for supra-aortic vessel disease (SVD, 24.6%), coronary heart disease (CHD, 40.4%), peripheral artery occlusive disease (PAOD, 34.2%), and visceral artery disease (1.7%). Involvement of >2 vascular territories was documented in 85%. Vascular risk factor frequency results were: previous (65.7%) or current (10.6%) tobacco use, hypertension (64.3%), hyperlipidaemia (75.4%), diabetes (25.8%), overweight (43.8%), and obesity (25.2%). LDL-cholesterol was >100 mg/dL for 38.1%, most frequently seen in patients with PAOD referral (P<0.001) or history (P=0.002), and for 29.2% of the patients taking a statin. HbA1c levels were >6.5% for 53.8% of patients with diabetes. The triple combination of an antiplatelet agent, a statin, and a renin-angiotensin-system inhibitor was not prescribed often enough, especially for PAOD referrals (PAOD referrals, 45.1%; SVD referrals, 48.1%; CHD referrals, 65.9%). Independent risk factors for all-cause mortality were: a previous CHD or PAOD clinical event, body mass index <25 kg/m2, HbA1c >6.5%, and no aspirin treatment. CONCLUSION: Even at the time of revascularization, medical management of atherosclerosis was not optimal. The need for continuing education of physicians and patients remains essential.

Role of peripheral versus spinal 5-HT(7) receptors in the modulation of pain undersensitizing conditions.

Several studies have suggested that 5-HT(7) receptors are involved in nociceptive processing but the exact contribution of peripheral versus central 5-HT(7) receptors still needs to be elucidated. In the present study, the respective roles of peripheral and spinal 5-HT(7) receptors in the modulation of mechanical hypersensitivity were investigated under two different experimental pain conditions. In a first set of experiments, the selective 5-HT(7) receptor agonist, E-57431, was systemically, intrathecally or peripherally (intraplantarly) administered to rats sensitized by intraplantar injection of capsaicin. Oral administration of E-57431 (1.25-10 mg/kg) was found to exert a clear-cut dose-dependent reduction of capsaicin-induced mechanical hypersensitivity. Interestingly, intrathecal administration of E-57431 (100 µg) also inhibited mechanical hypersensitivity secondary to capsaicin injection. In contrast, a dose-dependent enhancement of capsaicin-induced mechanical hypersensitivity was observed after local intraplantar injection of E-57431 (0.01-1 µg). In a second set of experiments, E-57431 was systemically or intrathecally administered to rats submitted to neuropathic pain (spared nerve injury model). Significant inhibition of nerve injury-induced mechanical hypersensitivity was found after intraperitoneal (10 mg/kg) as well as intrathecal (100 µg) administration of E-57431 in this chronic pain model. These studies provide evidence that, under sensitizing neurogenic/neuropathic conditions, activation of 5-HT(7) receptors exerts antinociceptive effects at the level of the spinal cord and pronociceptive effects at the periphery. The antinociceptive effect mediated by central 5-HT(7) receptors seems to predominate over the pronociceptive effect at the periphery when a selective 5-HT(7) receptor agonist is systemically administered.