RESUMO
During the onset of neuropathic pain from a variety of etiologies, nociceptors become hypersensitized, releasing neurotransmitters and other factors from centrally-projecting nerve terminals within the dorsal spinal cord. Consequently, glial cells (astrocytes and microglia) in the spinal cord are activated and mediate the release of proinflammatory cytokines that act to enhance pain transmission and sensitize mechanical non-nociceptive fibers which ultimately results in light touch hypersensitivity, clinically observed as allodynia. Pramipexole, a D2/D3 preferring agonist, is FDA-approved for the treatment of Parkinson's disease and demonstrates efficacy in animal models of inflammatory pain. The clinical-stage investigational drug, R(+) enantiomer of pramipexole, dexpramipexole, is virtually devoid of D2/D3 agonist actions and is efficacious in animal models of inflammatory and neuropathic pain. The current experiments focus on the application of a mouse model of sciatic nerve neuropathy, chronic constriction injury (CCI), that leads to allodynia and is previously characterized to generate spinal glial activation with consequent release IL-1ß. We hypothesized that both pramipexole and dexpramipexole reverse CCI-induced chronic neuropathy in mice, and in human monocyte cell culture studies (THP-1 cells), pramipexole prevents IL-1ß production. Additionally, we hypothesized that in rat primary splenocyte culture, dexpramixole increases mRNA for the anti-inflammatory and pleiotropic cytokine, interleukin-10 (IL-10). Results show that following intravenous pramipexole or dexpramipexole, a profound decrease in allodynia was observed by 1 hr, with allodynia returning 24 hr post-injection. Pramipexole significantly blunted IL-1ß protein production from stimulated human monocytes and dexpramipexole induced elevated IL-10 mRNA expression from rat splenocytes. The data support that clinically-approved compounds like pramipexole and dexpramipexole support their application as anti-inflammatory agents to mitigate chronic neuropathy, and provide a blueprint for future, multifaceted approaches for opioid-independent neuropathic pain treatment.
Assuntos
Neuralgia , Traumatismos dos Nervos Periféricos , Neuropatia Ciática , Camundongos , Ratos , Humanos , Animais , Interleucina-10/metabolismo , Hiperalgesia/metabolismo , Pramipexol , Drogas em Investigação/metabolismo , Drogas em Investigação/uso terapêutico , Citocinas/metabolismo , Neuralgia/metabolismo , Neuropatia Ciática/metabolismo , Medula Espinal/metabolismo , Nervo Isquiático/metabolismo , Traumatismos dos Nervos Periféricos/metabolismo , Técnicas de Cultura de CélulasRESUMO
We recently described a non-viral gene therapy paradigm offering long-term resolution of established neuropathic pain in several animal models. Here, the requirements for long-term therapeutic effects are described, and evidence is provided for a mechanism of action based on immunological priming of the intrathecal (i.t.) space. Long-term pain reversal was achieved when two i.t. injections of various naked plasmid DNA doses were separated by 5 h to 3 days. We show that an initial DNA injection, regardless of whether a transgene is included, leads to an accumulation of phagocytic innate immune cells. This accumulation coincides with the time in which subsequent DNA injection efficacy is potentiated. We show the ability of non-coding DNA to induce short-term pain reversal that is dependent on endogenous interleukin-10 (IL-10) signaling. Long-term efficacy requires the inclusion of an IL-10(F129S) transgene in the second injection. Blockade of IL-10, by a neutralizing antibody, either between the two injections or after the second injection induces therapeutic failure. These results show that this gene therapy paradigm uses an initial 'priming' injection of DNA to induce accumulation of phagocytic immune cells, allowing for potentiated efficacy of a subsequent 'therapeutic' DNA injection in a time- and dose-dependent manner.
Assuntos
Terapia Genética/métodos , Manejo da Dor , Animais , DNA/imunologia , Modelos Animais de Doenças , Vetores Genéticos/imunologia , Imunidade Inata , Injeções Espinhais , Interleucina-10/genética , Interleucina-10/imunologia , Masculino , Dor/imunologia , Limiar da Dor , Plasmídeos/imunologia , Ratos , Ratos Sprague-DawleyRESUMO
Traditional approaches to treating chronic neuropathic pain largely focus on manipulations directly altering neuronal activity or neuron-to-neuron communication. Recently, however, it has become clear that glial cells (including microglia and astroglia) play a significant role in pain expression in a variety of neuropathic pain models. Multiple aspects of the inflammatory response of glial cells, commonly observed in neuropathic pain conditions, have been implicated in pain expression. Thus, glial cell inflammation has emerged as a potential therapeutic target in neuropathic pain. Our laboratory has been exploring the use of an anti-inflammatory cytokine, interleukin-10 (IL-10), to control glial inflammatory activation thereby controlling neuropathic pain. IL-10 protein delivery is limited by a short half-life and an inability to cross into the central nervous system from the periphery, making a centrally delivered gene therapy approach attractive. We have recently characterized a non-viral gene therapy approach using two injections of naked DNA to achieve long-term (>3 months) control of neuropathic pain in a peripheral nerve injury model. Timing and dose requirements leading to long-term pain control are discussed in this review, as is recent work using microparticle-encapsulated DNA to achieve long-term therapeutic efficacy with a single injection.
Assuntos
Terapia Genética/métodos , Manejo da Dor , Animais , Doença Crônica , DNA/administração & dosagem , Técnicas de Transferência de Genes , Interleucina-10/genética , Interleucina-10/fisiologia , Neuroglia/fisiologiaRESUMO
Multiple Sclerosis (MS) is an autoimmune inflammatory disease that presents clinically with a range of symptoms including motor, sensory, and cognitive dysfunction as well as demyelination and lesion formation in brain and spinal cord. A variety of animal models of MS have been developed that share many of the pathological hallmarks of MS including motor deficits (ascending paralysis), demyelination and axonal damage of central nervous system (CNS) tissue. In recent years, neuropathic pain has been recognized as a prevalent symptom of MS in a majority of patients. To date, there have been very few investigations into sensory disturbances in animal models of MS. The current work contains the first assessment of hind paw mechanical allodynia (von Frey test) over the course of a relapsing-remitting myelin oligodendrocyte glycoprotein induced experimental autoimmune encephalomyelitis (MOG-EAE) rat model of MS and establishes the utility of this model in examining autoimmune induced sensory dysfunction. We demonstrate periods of both decreased responsiveness to touch that precedes the onset of hind limb paralysis, and increased responsiveness (allodynia) that occurs during the period of motor deficit amelioration traditionally referred to as symptom remission. Furthermore, we tested the ability of our recently characterized anti-inflammatory IL-10 gene therapy to treat the autoimmune inflammation induced behavioral symptoms and tissue histopathological changes. This therapy is shown here to reverse inflammation induced paralysis, to reduce disease associated reduction in sensitivity to touch, to prevent the onset of allodynia, to reverse disease associated loss of body weight, and to suppress CNS glial activation associated with disease progression in this model.
Assuntos
Encefalomielite Autoimune Experimental/terapia , Terapia Genética/métodos , Interleucina-10/fisiologia , Esclerose Múltipla/terapia , Análise de Variância , Animais , Peso Corporal/fisiologia , Modelos Animais de Doenças , Encefalomielite Autoimune Experimental/induzido quimicamente , Encefalomielite Autoimune Experimental/fisiopatologia , Proteína Glial Fibrilar Ácida/metabolismo , Membro Posterior , Imuno-Histoquímica , Inflamação/imunologia , Inflamação/terapia , Interleucina-10/genética , Masculino , Atividade Motora/fisiologia , Esclerose Múltipla/induzido quimicamente , Esclerose Múltipla/fisiopatologia , Proteínas da Mielina , Glicoproteína Associada a Mielina , Glicoproteína Mielina-Oligodendrócito , Neuralgia/fisiopatologia , Neuralgia/terapia , Paralisia/fisiopatologia , Paralisia/terapia , Ratos , Ratos Endogâmicos , Medula Espinal/metabolismo , Fatores de TempoRESUMO
Microglia and/or astrocytes play a significant role in the creation and maintenance of exaggerated pain states with inflammatory and/or neuropathic etiologies. The chemokine, fractalkine, has several functions, including the newly recognized role of mediating neuropathic pain conditions. Although constitutively expressed and released during inflammation, increased release of fractalkine binds to and activates microglia leading to pathological pain. We review the critical role of fractalkine in neuron-to-glial communication after peripheral nerve injury and inflammation and explore anti-inflammatory cytokines like interleukin-10 as a novel and effective approach for clinical pain control.
Assuntos
Quimiocina CX3CL1/fisiologia , Neuroglia/metabolismo , Dor/patologia , Animais , Comunicação Celular/fisiologia , Terapia Genética/métodos , Humanos , Neurônios/metabolismo , Dor/metabolismo , Manejo da DorRESUMO
Fractalkine is a chemokine that is tethered to the extracellular surface of neurons. Fractalkine can be released, forming a diffusible signal. Spinal fractalkine (CX3CL1) is expressed by sensory afferents and intrinsic neurons, whereas its receptor (CX3CR1) is predominantly expressed by microglia. Pain enhancement occurs in response both to intrathecally administered fractalkine and to spinal fractalkine endogenously released by peripheral neuropathy. The present experiments examine whether fractalkine-induced pain enhancement is altered by a microglial inhibitor (minocycline) and/or by antagonists/inhibitors of three putative glial products implicated in pain enhancement: interleukin-1 (IL1), interleukin-6 (IL6) and nitric oxide (NO). In addition, it extends a prior study that demonstrated that intrathecal fractalkine-induced mechanical allodynia is blocked by a neutralizing antibody to the rat fractalkine receptor, CX3CR1. Here, intrathecal anti-CX3CR1 also blocked fractalkine-induced thermal hyperalgesia. Furthermore, blockade of microglial activation with minocycline prevented both fractalkine-induced mechanical allodynia (von Frey test) and thermal hyperalgesia (Hargreaves test). Microglial activation appears to lead to the release of IL1, given that pretreatment with IL1 receptor antagonist blocked both fractalkine-induced mechanical allodynia and thermal hyperalgesia. IL1 is not the only proinflammatory cytokine implicated, as a neutralizing antibody to rat IL6 also blocked fractalkine-induced pain facilitation. Lastly, NO appears to be importantly involved, as l-NAME, a broad-spectrum NO synthase inhibitor, also blocked fractalkine-induced effects. Taken together, these data support that neuronally released fractalkine enhances pain via activation of spinal cord glia. Thus, fractalkine may be a neuron-to-glia signal triggering pain facilitation.
Assuntos
Quimiocinas CX3C/farmacologia , Proteínas de Membrana/farmacologia , Dor/induzido quimicamente , Dor/fisiopatologia , Medula Espinal/fisiopatologia , Animais , Antibacterianos/farmacologia , Anticorpos Bloqueadores/farmacologia , Quimiocina CX3CL1 , Quimiocinas CX3C/administração & dosagem , Quimiocinas CX3C/antagonistas & inibidores , Inibidores Enzimáticos/farmacologia , Temperatura Alta , Hiperalgesia/prevenção & controle , Injeções Espinhais , Interleucina-6/farmacologia , Masculino , Proteínas de Membrana/administração & dosagem , Proteínas de Membrana/antagonistas & inibidores , Microglia/efeitos dos fármacos , Microinjeções , Minociclina/farmacologia , NG-Nitroarginina Metil Éster/farmacologia , Medição da Dor/efeitos dos fármacos , Limiar da Dor/efeitos dos fármacos , Estimulação Física , Ratos , Ratos Sprague-DawleyRESUMO
Recent evidence suggests that spinal cord glia can contribute to enhanced nociceptive responses. However, the signals that cause glial activation are unknown. Fractalkine (CX3C ligand-1; CX3CL1) is a unique chemokine expressed on the extracellular surface of spinal neurons and spinal sensory afferents. In the dorsal spinal cord, fractalkine receptors are primarily expressed by microglia. As fractalkine can be released from neurons upon strong activation, it has previously been suggested to be a neuron-to-glial signal that induces glial activation. The present series of experiments provide an initial investigation of the spinal pain modulatory effects of fractalkine. Intrathecal fractalkine produced dose-dependent mechanical allodynia and thermal hyperalgesia. In addition, a single injection of fractalkine receptor antagonist (neutralizing antibody against rat CX3C receptor-1; CX3CR1) delayed the development of mechanical allodynia and/or thermal hyperalgesia in two neuropathic pain models: chronic constriction injury (CCI) and sciatic inflammatory neuropathy. Intriguingly, anti-CX3CR1 reduced nociceptive responses when administered 5-7 days after CCI, suggesting that prolonged release of fractalkine may contribute to the maintenance of neuropathic pain. Taken together, these initial investigations of spinal fractalkine effects suggest that exogenous and endogenous fractalkine are involved in spinal sensitization, including that induced by peripheral neuropathy.
Assuntos
Quimiocinas CX3C/metabolismo , Proteínas de Membrana/metabolismo , Neuroglia/metabolismo , Nociceptores/fisiologia , Dor/metabolismo , Doenças do Sistema Nervoso Periférico/metabolismo , Medula Espinal/metabolismo , Animais , Anticorpos/farmacologia , Receptor 1 de Quimiocina CX3C , Comunicação Celular/efeitos dos fármacos , Comunicação Celular/fisiologia , Quimiocina CX3CL1 , Quimiocinas CX3C/administração & dosagem , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Hiperalgesia/induzido quimicamente , Hiperalgesia/metabolismo , Hiperalgesia/fisiopatologia , Injeções Espinhais , Ligadura , Masculino , Proteínas de Membrana/administração & dosagem , Proteínas de Membrana/efeitos dos fármacos , Microglia/efeitos dos fármacos , Microglia/metabolismo , Neuroglia/efeitos dos fármacos , Neurônios/metabolismo , Nociceptores/efeitos dos fármacos , Dor/induzido quimicamente , Dor/fisiopatologia , Doenças do Sistema Nervoso Periférico/induzido quimicamente , Doenças do Sistema Nervoso Periférico/fisiopatologia , Ratos , Ratos Sprague-Dawley , Receptores de Citocinas/antagonistas & inibidores , Receptores de Citocinas/metabolismo , Receptores de HIV/antagonistas & inibidores , Receptores de HIV/metabolismo , Neuropatia Ciática/induzido quimicamente , Neuropatia Ciática/metabolismo , Neuropatia Ciática/fisiopatologia , Medula Espinal/efeitos dos fármacos , Medula Espinal/fisiopatologiaRESUMO
Snakebites constitute a serious public health problem in Central and South America, where species of the lancehead pit vipers (genus Bothrops) cause the majority of accidents. Bothrops envenomations are very painful, and this effect is not neutralized by antivenom treatment. Two variants of secretory phospholipases A2 (sPLA2), corresponding to Asp49 and Lys49 PLA2s, have been isolated from Bothrops asper venom. These sPLA2s induce hyperalgesia in rats following subcutaneous injection. However, venom in natural Bothrops bites is frequently delivered intramuscularly, thereby potentially reaching peripheral nerve bundles. Thus, the present series of experiments tested whether these sPLA2s could exert pain-enhancing effects following administration around healthy sciatic nerve. Both were found to produce mechanical allodynia ipsilateral to the injection site; no thermal hyperalgesia was observed. As no prior study has examined potential spinal mechanisms underlying sPLA2 actions, a series of anatomical and pharmacological studies were performed. These demonstrated that both sPLA2s produce activation of dorsal horn astrocytes and microglia that is more prominent ipsilateral to the site of injection. As proinflammatory cytokines and nitric oxide have each been previously implicated in spinally mediated pain facilitation, the effect of pharmacological blockade of these substances was tested. The results demonstrate that mechanical allodynia induced by both sPLA2s is blocked by interleukin-1 receptor antagonist, anti-rat interleukin-6 neutralizing antibody, the anti-inflammatory cytokine interleukin-10, and a nitric oxide synthesis inhibitor (L-NAME). As a variety of immune cells also produce and release sPLA2s during inflammatory states, the data may have general implications for the understanding of inflammatory pain. © 2003 International Association for the Study of Pain.
Assuntos
Animais , Citocinas , /intoxicação , Óxido Nítrico/intoxicaçãoRESUMO
Pain is classically viewed as being mediated solely by neurons, as are other sensory phenomena. The discovery that spinal cord glia (microglia and astrocytes) amplify pain requires a change in this view. These glia express characteristics in common with immune cells in that they respond to viruses and bacteria, releasing proinflammatory cytokines, which create pathological pain. These spinal cord glia also become activated by certain sensory signals arriving from the periphery. Similar to spinal infection, these signals cause release of proinflammatory cytokines, thus creating pathological pain. Taken together, these findings suggest a new, dramatically different approach to pain control, as all clinical therapies are focused exclusively on altering neuronal, rather than glial, function.
Assuntos
Neuroglia/fisiologia , Dor/fisiopatologia , Medula Espinal/citologia , Medula Espinal/fisiologia , Animais , HumanosRESUMO
Perispinal (intrathecal) injection of the human immunodeficiency virus-1 (HIV-1) envelope glycoprotein gp120 creates exaggerated pain states. Decreases in response thresholds to both heat stimuli (thermal hyperalgesia) and light tactile stimuli (mechanical allodynia) are rapidly induced after gp120 administration. gp120 is the portion of HIV-1 that binds to and activates microglia and astrocytes. These glial cells have been proposed to be key mediators of gp120-induced hyperalgesia and allodynia because these pain changes are blocked by drugs thought to affect glial function preferentially. The aim of the present series of studies was to determine whether gp120-induced pain changes involve proinflammatory cytokines [interleukin-1beta (IL-1) and tumor necrosis factor-alpha (TNF-alpha)], substances released from activated glia. IL-1 and TNF antagonists each prevented gp120-induced pain changes. Intrathecal gp120 produced time-dependent, site-specific increases in TNF and IL-1 protein release into lumbosacral CSF; parallel cytokine increases in lumbar dorsal spinal cord were also observed. Intrathecal administration of fluorocitrate (a glial metabolic inhibitor), TNF antagonist, and IL-1 antagonist each blocked gp120-induced increases in spinal IL-1 protein. These results support the concept that activated glia in dorsal spinal cord can create exaggerated pain states via the release of proinflammatory cytokines.
Assuntos
Citocinas/administração & dosagem , Proteína gp120 do Envelope de HIV/administração & dosagem , Hiperalgesia/metabolismo , Dor/metabolismo , Medula Espinal/metabolismo , Animais , Citratos/administração & dosagem , Modelos Animais de Doenças , Temperatura Alta , Hiperalgesia/induzido quimicamente , Hiperalgesia/fisiopatologia , Injeções Espinhais , Proteína Antagonista do Receptor de Interleucina 1 , Interleucina-1/administração & dosagem , Interleucina-1/antagonistas & inibidores , Interleucina-1/metabolismo , Região Lombossacral , Masculino , Pescoço , Dor/fisiopatologia , Medição da Dor/efeitos dos fármacos , Estimulação Física , Ratos , Ratos Sprague-Dawley , Receptores de Interleucina-1/antagonistas & inibidores , Receptores do Fator de Necrose Tumoral/administração & dosagem , Receptores Tipo I de Fatores de Necrose Tumoral , Sialoglicoproteínas/administração & dosagem , Medula Espinal/efeitos dos fármacos , Medula Espinal/fisiopatologia , Receptores Chamariz do Fator de Necrose Tumoral , Fator de Necrose Tumoral alfa/administração & dosagem , Fator de Necrose Tumoral alfa/antagonistas & inibidores , Fator de Necrose Tumoral alfa/metabolismoRESUMO
We have recently developed a model of sciatic inflammatory neuritis (SIN) to assess how immune activation near peripheral nerves influences somatosensory processing. Administration of zymosan (yeast cell walls) around a single sciatic nerve produces dose-dependent low-threshold mechanical allodynia without thermal hyperalgesia. Low (4 microg) doses produce both territorial and extraterritorial allodynia restricted to the injected hindleg. In contrast, higher (40 microg) doses produce territorial and extraterritorial allodynias of both hindlegs, an effect not accounted for by systemic spread of the zymosan. The aim of these experiments was to determine whether these behavioral allodynias were correlated with immunological and/or anatomical changes in or around the sciatic nerve. These experiments reveal that zymosan-induced bilateral allodynia was associated with the following: (a) increased release of both interleukin-1beta and tumor necrosis factor-alpha from peri-sciatic immune cells; (b) increased release of reactive oxygen species from perisciatic immune cells; (c) no change in circulating levels of proinflammatory cytokine; (d) no apparent zymosan-induced influx of immune cells into the sciatic nerve from the endoneurial blood vessels; (e) mild edema of the sciatic, which was predominantly restricted to superficial regions closest to the peri-sciatic immune cells; and (f) no anatomic evidence of changes in either the ipsilateral saphenous nerve or contralateral sciatic nerve that could account for the appearance of extraterritorial or contralateral ("mirror") allodynia, respectively. No reliable differences were found when the low-dose zymosan was compared with vehicle controls. Taken together, these data suggest that substances released by peri-sciatic immune cells may induce changes in the sciatic nerve, leading to the appearance of bilateral allodynia.
Assuntos
Citocinas/metabolismo , Neuropatia Ciática/imunologia , Neuropatia Ciática/metabolismo , Superóxidos/metabolismo , Animais , Comportamento Animal , Modelos Animais de Doenças , Citometria de Fluxo , Esponja de Gelatina Absorvível , Imuno-Histoquímica , Interleucina-1/metabolismo , Interleucina-6/metabolismo , Leucócitos/citologia , Leucócitos/efeitos dos fármacos , Medições Luminescentes , Contagem de Linfócitos , Masculino , Medição da Dor , Ratos , Ratos Sprague-Dawley , Nervo Isquiático/imunologia , Nervo Isquiático/patologia , Neuropatia Ciática/induzido quimicamente , Organismos Livres de Patógenos Específicos , Fator de Necrose Tumoral alfa/metabolismo , Degeneração Walleriana/imunologia , Zimosan/farmacologiaRESUMO
Intrathecal administration of the human immunodeficiency virus-1 envelope glycoprotein, gp120, activates astrocytes and microglia to release products that induce thermal hyperalgesia and mechanical allodynia. Both pain states are disrupted by intrathecal CNI-1493, a p38 mitogen-activated protein (MAP) kinase inhibitor. Whether CNI-1493, or any other p38 MAP kinase inhibitor, can cross the blood-brain barrier to affect spinal cord function is unknown. Given that several such drugs are in clinical trials, it is of interest to determine whether they may be potentially useful in treating centrally mediated pain. The aim of the present studies was to determine whether systemic CNI-1493 could block intrathecal gp120-induced thermal hyperalgesia and/or mechanical allodynia. Because p38 MAP kinase inhibition would be expected to prevent proinflammatory cytokine release and/or signal transduction, we sought to determine from the same animals the likely mechanism by which CNI-1493 blocks gp120-induced pain states. These studies show that systemic CNI-1493 blocks intrathecal gp120-induced thermal hyperalgesia and mechanical allodynia. Because CNI-1493 did not block proinflammatory cytokine release, this may suggest disruption at the level of signal transduction. These studies provide the first evidence that systemic p38 MAP kinase inhibitors can prevent centrally mediated exaggerated pain states. Thus, CNI-1493 may provide a novel therapeutic approach for the treatment of pain.
RESUMO
Astrocytes and microglia in the spinal cord have recently been reported to contribute to the development of peripheral inflammation-induced exaggerated pain states. Both lowering of thermal pain threshold (thermal hyperalgesia) and lowering of response threshold to light tactile stimuli (mechanical allodynia) have been reported. The notion that spinal cord glia are potential mediators of such effects is based on the disruption of these exaggerated pain states by drugs thought to preferentially affect glial function. Activation of astrocytes and microglia can release many of the same substances that are known to mediate thermal hyperalgesia and mechanical allodynia. The aim of the present series of studies was to determine whether exaggerated pain states could also be created in rats by direct, intraspinal immune activation of astrocytes and microglia. The immune stimulus used was peri-spinal (intrathecal, i.t.) application of the Human Immunodeficiency Virus type 1 (HIV-1) envelope glycoprotein, gp120. This portion of HIV-1 is known to bind to and activate microglia and astrocytes. Robust thermal hyperalgesia (tail-flick, TF, and Hargreaves tests) and mechanical allodynia (von Frey and touch-evoked agitation tests) were observed in response to i.t. gp120. Heat denaturing of the complex protein structure of gp120 blocked gp120-induced thermal hyperalgesia. Lastly, both thermal hyperalgesia and mechanical allodynia to i.t. gp120 were blocked by spinal pretreatment with drugs (fluorocitrate and CNI-1493) thought to preferentially disrupt glial function.
Assuntos
Proteína gp120 do Envelope de HIV/efeitos adversos , Hiperalgesia/induzido quimicamente , Neuroglia/efeitos dos fármacos , Animais , Anti-Inflamatórios não Esteroides/uso terapêutico , Citratos/uso terapêutico , Temperatura Alta/efeitos adversos , Hidrazonas/uso terapêutico , Hiperalgesia/tratamento farmacológico , Masculino , Ratos , Ratos Sprague-Dawley , Organismos Livres de Patógenos Específicos , Medula Espinal/efeitos dos fármacos , Tato/efeitos dos fármacosRESUMO
A method for direct catheterization of the lumbar subarachnoid space has recently been developed by Storkson et al. (1996) (J Neurosci Methods 1996;65:167-172) that may potentially improve upon the widely used method of Yaksh and Rudy (1976) (Physiol Behav 1976;17:1031-1036). This 'catheter-through-a-needle' technique inserts the catheter between lumbar vertebrae 5 (L5) and 6 (L6), which has been shown to reduce neurological impairment and post-surgical deaths. However, employing this technique allows the external portion of the chronic indwelling catheters to be easily damaged, resulting in approximately 50% attrition within 4 days after surgery. Therefore, we developed an easy and inexpensive method for protecting the external portion of the catheter that enhances catheter viability beyond 14 days after catheter implantation while also maintaining a low injection volume (8 microl). Moreover, this modification does not significantly alter the implantation methods developed by Storkson et al. (1996) (J Neurosci Methods 1996;65:167-172) and allows for more optimal catheter materials to be incorporated. Chronically implanted catheters (n = 70) with the external portion of the catheter protected, resulted in 4% attrition 7 days after surgery and 11% attrition 14 days after surgery. Approximately 5.5% of animals implanted showed very mild and transient neurological impairment.
Assuntos
Cateterismo/métodos , Medula Espinal , Animais , Região Lombossacral , Masculino , Transtornos das Habilidades Motoras/etiologia , Paresia/etiologia , Complicações Pós-Operatórias , Ratos , Ratos Sprague-Dawley , Espaço SubaracnóideoRESUMO
We have shown that chronic cold stress strongly interacts with corticosterone (B) to determine subsequent regulation of the hypothalamo-pituitary-adrenal (HPA) axis responses to novel stress. These studies, using the same 2 sets of rats, show that chronic cold also interacts with B and testosterone on signals of energy balance. The two groups of rats differed in weight by 20% and in age by 2 weeks (44-59 days of age). Adrenalectomized rats, replaced with varying doses of B, were exposed to cold or served as controls. Food intake and body weight during the experiments and hormones, metabolites and fat depots were measured on day 5. B, but not cold, affected food intake in the younger rats; by contrast, cold, but not B, affected food intake in the older rats. Testosterone was higher in older control rats and was markedly depressed by cold; younger rats had lower testosterone that was minimally affected by cold. Weight gain decreased in all rats at room temperature with increasing B, whereas they all lost weight in cold independently of B. Cold stimulated and B inhibited interscapular brown adipose tissue DNA content (reflecting sympathetic stimulation of thermogenesis). B stimulated insulin, whereas cold inhibited leptin and insulin; B also increased white adipose tissue weight gain in controls and inhibited its loss in cold. Leptin was unrelated to white adipose tissue depots in older control rats but was strongly related to these stores in younger rats and in all rats in cold. We conclude that: 1. By decreasing signals that act centrally to inhibit food intake (insulin, leptin and testosterone) cold allows B to stimulate food intake; 2. B inhibits weight gain although it causes accrual of fat; 3. Cold, probably through sympathetic stimulation of white adipose tissue, causes fat loss which is modulated by the inhibitory effect of B on sympathetic outflow; and, 4. The slope of the relationship between fat depot size and leptin becomes flatter in cold, possibly because of increased sympathetic outflow to these depots.
Assuntos
Tecido Adiposo Marrom/metabolismo , Temperatura Baixa , Corticosterona/sangue , Metabolismo Energético/fisiologia , Maturidade Sexual/fisiologia , Estresse Fisiológico/metabolismo , Tecido Adiposo Marrom/efeitos dos fármacos , Adrenalectomia , Animais , Glicemia , Peso Corporal , Corticosterona/farmacologia , Ingestão de Alimentos , Metabolismo Energético/efeitos dos fármacos , Glucagon/análise , Sistema Hipotálamo-Hipofisário/fisiologia , Insulina/sangue , Leptina/sangue , Masculino , Sistema Hipófise-Suprarrenal/fisiologia , Ratos , Ratos Sprague-Dawley , Testosterona/sangue , Triglicerídeos/sangueRESUMO
Both intracerebroventricular (i.c.v.) IL-1beta and exposure to inescapable tail shock (IS) activate acute phase responses (APRs) that include increases in core body temperature (CBT), increases in hypothalamic-pituitary-adrenal activity, decreases in carrier proteins such as corticosterone binding globulin (CBG), aphagia and adipsia. A variety of data suggested that stressors produce APRs by inducing brain IL-1beta. The current series of studies further explored this possibility by determining whether the functional IL-1beta antagonist, alpha-melanocyte-stimulating hormone (alpha-MSH(1-13)), would block IS-induced APRs. Immediately following i.c.v. alpha-MSH(1-13) administration, rats were exposed to a single session of 100, 5 s, 1.6 mA ISs, or control treatment (home cage control). alpha-MSH(1-13) blocked IS-induced increased CBT, increased plasma corticosterone (CORT), decreased CBG, aphagia and adipsia 24 h after IS. The inhibitory effects of alpha-MSH(1-13) were shown not to be a consequence of alpha-MSH(1-13) producing its actions 24 h after its administration because alpha-MSH(1-13) given 24 h before IS did not block IS-induced increased CBT and CORT during IS. Additionally, alpha-MSH(1-13), given 24 h before IS, had no effect on increased CBT, increased CORT, decreased CBG, adipsia, or aphagia 24 h after IS. These data provide support for a specific mode of action for i.c.v. alpha-MSH(1-13), namely blockade of APRs with no impact on acute hyperthermia or increased levels of CORT produced during IS.
Assuntos
Reação de Fase Aguda/prevenção & controle , Estresse Psicológico/complicações , alfa-MSH/farmacologia , Reação de Fase Aguda/fisiopatologia , Reação de Fase Aguda/psicologia , Animais , Temperatura Corporal/fisiologia , Ingestão de Líquidos/fisiologia , Ingestão de Alimentos/fisiologia , Hidrocortisona/sangue , Injeções Intraventriculares , Masculino , Ratos , Ratos Sprague-Dawley , alfa-MSH/administração & dosagemRESUMO
Brain-mediated sickness responses can be blocked by subdiaphragmatic vagotomy, suggesting that vagal afferents signal peripheral inflammation or infection. This study tested whether subdiaphragmatic vagotomy disrupts sickness responses by interrupting effector pathways. If this explanation is correct, intracerebroventricular prostaglandin E2-induced fever should be blocked by this procedure. Fever was unaffected by subdiaphragmatic vagotomy, thus these data provide support for the conclusion that vagal afferents signal the brain during immune activation.
Assuntos
Diafragma/inervação , Dinoprostona/farmacologia , Febre/induzido quimicamente , Neuroimunomodulação/fisiologia , Ocitócicos/farmacologia , Vagotomia , Nervo Vago/imunologia , Animais , Injeções Intraventriculares , Masculino , Neurônios Aferentes/efeitos dos fármacos , Neurônios Aferentes/fisiologia , Gânglio Nodoso/citologia , Gânglio Nodoso/efeitos dos fármacos , Proteínas Proto-Oncogênicas c-fos/biossíntese , Ratos , Ratos Sprague-Dawley , Organismos Livres de Patógenos Específicos , Nervo Vago/citologia , Nervo Vago/cirurgiaRESUMO
OBJECTIVE: To determine the use of new drugs in one United Kingdom region. DESIGN: Examination of data on prescribing of angiotensin converting enzyme inhibitors, new broad spectrum antibiotics, and H2 receptor antagonists. Calculation of number of defined daily doses prescribed each month. SETTING: All general practices in Northern Ireland. MAIN OUTCOME MEASURES: Drug use index and market share of each drug. RESULTS: During 1988-91 prescribing of angiotensin converting enzyme inhibitors increased by 126%, of H2 receptor antagonists by 46%, and of new antibiotics by 207%. The first drug on the market usually retained the largest market share. Use of oral antibiotics increased threefold irrespective of the reporting policy of the general practitioners' local laboratory. CONCLUSIONS: The increase in prescribing of these drugs seems to be greater than can be accounted for by an increase in patients with specific indications for these drugs. This suggests that the profession has not instituted effective checks to ensure that the legitimate promotion of new products does not lead to inappropriate and wasteful use.
Assuntos
Inibidores da Enzima Conversora de Angiotensina/uso terapêutico , Antibacterianos/uso terapêutico , Revisão de Uso de Medicamentos/estatística & dados numéricos , Medicina de Família e Comunidade/estatística & dados numéricos , Indústria Farmacêutica , Prescrições de Medicamentos/estatística & dados numéricos , Medicina de Família e Comunidade/normas , Antagonistas dos Receptores H2 da Histamina/uso terapêutico , Humanos , Irlanda do Norte , Padrões de Prática Médica/estatística & dados numéricosRESUMO
Six new placental alkaline phosphatase monoclonal antibodies (MAbs) have been evaluated in order to select a potentially clinically useful antibody fragment for use in immunoscintigraphy or therapy. Initially, 3 antibodies were identified by trial pepsin digestion as likely to give satisfactory F(ab')2 yield. The corresponding intact antibodies were then compared for ability to localise human xenograft tumours in athymic mice. Of the best of these, designated 3F6, F(ab')2 and Fab fragments were then evaluated in similar xenograft experiments. In intact antibody biodistribution comparisons, 3F6 showed good tumour retention and satisfactory specific/non-specific ratios at 8 days. In similar fragment biodistribution experiments 3F6 F(ab')2 gave the highest tumour/blood ratio (10) and tumour/organ ratios (19) and the best specific/non-specific localisation. This fragment also showed higher absolute uptake in the tumour than intact antibody, 18.9% and 14.4% respectively of the injected dose. As expected, fragments showed much faster blood clearance rates than whole antibody. For Fab the in vivo instability by 6 hr was also demonstrated.