Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0026838 (spasticity)
 6,471 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Metabotropic gamma-aminobutyric acid(B) (GABAB) receptors for the major inhibitory transmitter GABA, together with metabotropic glutamate (mGLuRs) receptors, the extracellular calcium-sensing receptors (CaSRs), some V2R pheromone receptors and T1R taste receptors, belong to the family of 3 G-protein-coupled receptors (GPCRs). GABAB receptors are known to control neuronal excitability and modulate synaptic neurotransmission, playing a very important role in many physiological activities. These receptors are widely expressed and distributed in the nervous system and have been implicated in a variety of neurodegenerative and pathophysiological disorders including epilepsy, spasticity, chronic pain, depression, schizophrenia and drug addiction. To form a functional receptor entity, GABAB receptors must exist as a heterodimer consisting of GABAB1 and GABAB2 receptor subtypes with two 7-transmembrane proteins, and these subunits arise from distinct genes. The GABAB1 subunit binds the endogenous ligand within its extracellular N-terminus, whilst the GABAB2 subunit is not only essential for the correct trafficking of the GABAB1 subunit to the cell surface, but is also responsible for the interaction of the receptor with its cognate G-protein. Allosteric modulation has recently been recognized as an alternative pharmacological approach to gain selectivity in drug action. It is now generally accepted that modulators acting at the allosteric sites provide a novel perspective for the development of subtype-selective agents acting at GPCRs. These agents interact with allosteric binding sites quite separate from the highly conserved agonist binding region. In this review, we present a new class of phenylalkylamines, based on the lead compound fendiline, that are potent positive potentiators of GABAB receptor-mediated function and discuss their putative clinical applications. It is proposed that these new modulators may have therapeutic value in GABAB receptor pharmacology and are capable of selectively modifying GABAB receptor function. The allosteric modulators are offering an attractive and novel means to identify new leads, that are devoid of side effects associated with GABAB receptor agonists, and may, therefore, represent a major advance in the drug discovery process.
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PMID:Clinical potential of GABAB receptor modulators. 1638 96

gamma-Aminobutyric acid (GABA) emerged as a potentially important brain chemical just over 50 years ago, but its significance as a neurotransmitter was not fully realized until over 16 years later. We now know that at least 40% of inhibitory synaptic processing in the mammalian brain uses GABA. Establishing its role as a transmitter was a lengthy process and it seems hard to believe with our current knowledge that there was ever any dispute about its role in the mammalian brain. The detailed information that we now have about the receptors for GABA together with the wealth of agents which facilitate or reduce GABA receptor mechanisms make the prospects for further research very exciting. The emergence of glycine as a transmitter seems relatively painless by comparison to GABA. Perhaps this is appropriate for the simplest of transmitter structures! Its discovery within the spinal cord and brainstem approximately 40 years ago was followed only 2 years later by the proposal that it be conferred with 'neurotransmitter' status. It was another 16 years before the receptor was biochemically isolated. Now it is readily accepted as a vital spinal and supraspinal inhibitory transmitter and we know many details regarding its molecular structure and trafficking around neurones. The pharmacology of these receptors has lagged behind that of GABA. There is not the rich variety of allosteric modulators that we have come to readily associate with GABA receptors and which has provided us with a virtual treasure trove of important drugs used in anxiety, insomnia, epilepsy, anaesthesia, and spasticity, all stemming from the actions of the simple neutral amino acid GABA. Nevertheless, the realization that glycine receptors are involved in motor reflexes and nociceptive pathways together with the more recent advent of drugs that exhibit some subtype selectivity make the goal of designing selective therapeutic ligands for the glycine receptor that much closer.
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PMID:GABA and glycine as neurotransmitters: a brief history. 1640 94

Antiepileptic drugs (AEDs) affect various neurotransmitters (i.e. GABA, glutamate), receptors (i.e. GABAergic, glutamatergic), and ion channels (i.e. for sodium or calcium) which is responsible for their anticonvulsant activity. However, this broad spectrum of action may be also utilized in other pathological conditions. For example, both conventional and newer AEDs may be used in patients suffering from neuropathic pain, migraine, essential tremor, spasticity, restless legs syndrome and a number of psychiatric disorders (f.e. bipolar disease or schizophrenia). Also, isolated data point to their potential use in Parkinson's or Alzheimer's disease. There is experimental background indicating a potent neuroprotective efficacy of AEDs in numerous models of brain ischemia. However, the clinical data are very limited and this problem requires careful assessment.
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PMID:Non-epilepsy uses of antiepilepsy drugs. 1653 24

Transient spinal cord ischemia may lead to a progressive degeneration of spinal interneurons and subsequently to increased hind limb motor tone. In the present work we sought to characterize the rigidity and spasticity components of this altered motor function by: i) tonic electromyographic activity measured in gastrocnemius muscle before and after ischemia, ii) measurement of muscle resistance during the period of ankle flexion and corresponding changes in electromyographic activity, iii) changes in Hoffmann reflex, and, iv) motor evoked potentials. In addition the effect of intrathecal treatment with baclofen (GABAB receptor agonist; 1 microg), nipecotic acid (GABA uptake inhibitor; 300 microg) and dorsal L2-L5 rhizotomy on spasticity and rigidity was studied. Finally, the changes in spinal choline acetyltransferase (ChAT) and vesicular glutamate transporter 2 and 1 (VGLUT2 and VGLUT1) expression were characterized using immunofluorescence and confocal microscopy. At 3-7 days after ischemia an increase in tonic electromyographic activity with a variable degree of rigidity was seen. In animals with modest rigidity a velocity-dependent increase in muscle resistance and corresponding appearance in electromyographic activity (consistent with the presence of spasticity) was measured during ankle rotation (4-612 degrees /s rotation). Measurement of the H-reflex revealed a significant increase in Hmax/Mmax ratio and a significant loss of rate-dependent inhibition. In the same animals a potent increase in motor evoked potential amplitudes was measured and this change correlated positively with the increased H-reflex responses. Spasticity and rigidity were consistently present for a minimum of 3 months after ischemia. Intrathecal treatment with baclofen (GABA B receptor agonist) and nipecotic acid (GABA uptake inhibitor) provided a significant suppression of spasticity, rigidity, H-reflex or motor evoked potentials. Dorsal L2-L5 rhizotomy significantly decreased muscle resistance but had no effect on increased amplitudes of motor evoked potentials. Confocal analysis of spinal cord sections at 8 weeks-12 months after ischemia revealed a continuing presence of ChAT positive alpha-motoneurons, Ia afferents and VGLUT2 and VGLUT1-positive terminals but a selective loss of small presumably inhibitory interneurons between laminae V-VII. These data demonstrate that brief transient spinal cord ischemia in rat leads to a consistent development of spasticity and rigidity. The lack of significant suppressive effect of dorsal L2-L5 rhizotomy on motor evoked potentials response indicates that descending motor input into alpha-motoneurons is independent on Ia afferent couplings and can independently contribute to increased alpha-motoneuronal excitability. The pharmacology of this effect emphasizes the potent role of GABAergic type B receptors in regulating both the spasticity and rigidity.
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PMID:Development of GABA-sensitive spasticity and rigidity in rats after transient spinal cord ischemia: a qualitative and quantitative electrophysiological and histopathological study. 1679 37

Transient spinal cord ischemia in humans can lead to the development of permanent paraplegia with prominent spasticity and rigidity. Histopathological analyses of spinal cords in animals with ischemic spastic paraplegia show a selective loss of small inhibitory interneurons in previously ischemic segments but with a continuing presence of ventral alpha-motoneurons and descending cortico-spinal and rubro-spinal projections. The aim of the present study was to examine the effect of human spinal stem cells (hSSCs) implanted spinally in rats with fully developed ischemic paraplegia on the recovery of motor function and corresponding changes in motor evoked potentials. In addition the optimal time frame for cell grafting after ischemia and the optimal dosing of grafted cells were also studied. Spinal cord ischemia was induced for 10 min using aortic occlusion and systemic hypotension. In the functional recovery study, hSSCs (10,000-30,000 cells/0.5 mul/injection) were grafted into spinal central gray matter of L2-L5 segments at 21 days after ischemia. Animals were immunosuppressed with Prograf (1 mg/kg or 3 mg/kg) for the duration of the study. After cell grafting the recovery of motor function was assessed periodically using the Basso, Beattie and Bresnahan (BBB) scoring system and correlated with the recovery of motor evoked potentials. At predetermined times after grafting (2-12 weeks), animals were perfusion-fixed and the survival, and maturation of implanted cells were analyzed using antibodies recognizing human-specific antigens: nuclear protein (hNUMA), neural cell adhesion molecule (hMOC), neuron-specific enolase (hNSE) and synapthophysin (hSYN) as well as the non-human specific antibodies TUJ1, GFAP, GABA, GAD65 and GLYT2. After cell grafting a time-dependent improvement in motor function and suppression of spasticity and rigidity was seen and this improvement correlated with the recovery of motor evoked potentials. Immunohistochemical analysis of grafted lumbar segments at 8 and 12 weeks after grafting revealed intense hNSE immunoreactivity, an extensive axo-dendritic outgrowth as well as rostrocaudal and dorsoventral migration of implanted hNUMA-positive cells. An intense hSYN immunoreactivity was identified within the grafts and in the vicinity of persisting alpha-motoneurons. On average, 64% of hSYN terminals were GAD65 immunoreactive which corresponded to GABA immunoreactivity identified in 40-45% of hNUMA-positive grafted cells. The most robust survival of grafted cells was seen when cells were grafted 21 days after ischemia. As defined by cell survival and laminar distribution, the optimal dose of injected cells was 10,000-30,000 cells per injection. These data indicate that spinal grafting of hSSCs can represent an effective therapy for patients with spinal ischemic paraplegia.
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PMID:Functional recovery in rats with ischemic paraplegia after spinal grafting of human spinal stem cells. 1752 65

Baclofen (beta-p-chlorophenyl-GABA) binds to a number of spinal and cerebral sites and depresses the excitability of motor neurons. Intrathecal administration induces much higher CSF concentrations compared to the limited passage through the blood-brain barrier after oral administration. The development of reliable implanted pumps allows long-term intrathecal baclofen treatment (ITB). Baclofen is mainly an antispastic drug and the main indication of ITB is generalized lower limb spasticity in spinal cord injury and multiple sclerosis. The side-effects are due to either drug over-dose or withdrawal and to malfunctions of the implanted device (disconnections of the catheter, infections, etc.). Large numbers of patients have been treated over the past twenty years. More recently, baclofen has been used in the treatment of spasticity of cerebral origin, and in the treatment of other motor disorders, mainly dystonia. The results in cerebral palsy are promising and ITB's role will probably grow in the management of the movement disorders of these children. Further studies are required on the exact site of action, on the possible association with other drugs, especially clonidine and on the development of sustained release formulations.
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PMID:Intrathecal baclofen in the treatment of spasticity, dystonia and vegetative disorders. 1769 79

Adjuvant analgesics are drugs that are not primarily used as analgesics but can produce analgesia in certain types of pain. Adjuvant analgesics can be administered together with non-opioid and opioid analgesics on each step of the WHO analgesic ladder. They should be given when an additional or specific indication exists, but should not be used as a substitute for a thorough treatment with opioids and nonopioids. Adjuvant analgesics can be classified into groups according to the type of pain to be treated: continuous neuropathic pain or lancinating neuropathic pain, sympathetically maintained pain, bone pain and those for multipurpose use. Adjuvant drugs used for continuous neuropathic pain include local anaesthetics, clonidine, capsaicin, and antidepressants. Tricyclic antidepressants are the group that have been best investigated, and are therefore the drugs of choice. An analgesic effect is probably produced via enhancement of transmitter concentrations in pain-modulating pathways. This occurs at lower doses than those necessary to treat depression. Anticholinergic actions, acute glaucoma, constipation, orthostatic hypotension and cardiac arrhythmias are adverse effects that are seen predominantly with teritiary amine drugs and less often with secondary amine compounds. Initial doses should be small to avoid these adverse effects. Local anaesthetics are used less often, because of the high incidence of side effects (especially with tocainide, flecainide). An analgesic effect has been described in neuropathic pain, however, probably due to membrane stabilization and reduction of aberrant signal conduction. Mexiletine is considered to be the safest local anaesthetic, and should be used initially in small doses (100-150 mg/d). If side effects do not occur, doses can be increased step-wise up to 900 mg/d. Local anaesthetics are indicated for the treatment of severe neuropathic pain; this treatment is contraindicated in patients with cardiac arrhythmias. Systemic or intrathecal clonidine can be tried in neuropathic pain refractory to opioid therapy. The same stands for the topical application of capsaicin in certain types of pain. Lancinating neuropathic pain is an indication for anticonvulsant drugs. Carbamazepine, clonazepam, valproate and phenytoin seem to reduce aberrant signal conduction in damaged nerves in a manner similar to the supression of epileptiform activities in the brain. Common side effects include sedation, dizziness and nausea. Of greater concern are the more severe side effects, such as bone marrow depression (carbamazepine) and hepatotoxicity (phenytoin, valproate). Low initial doses and stepwise increases in dosage, repeated blood counts, and monitoring of plasma levels are helpful in recognizing and avoiding these adverse effects. Baclofen, a GABA agonist primarily used for spasticity, is effective in the treatment of trigeminal neuralgia and is often used in the management of lancinating pain of unspecific origin. The initial dosage is 10-15 mg/d, increasing to 30-90 mg/d, or higher. If neural blockade fails to reduce sympathetically maintained pain sufficiently specific adjuvants can be used. Sympatholytic drugs, e.g. phenoxybenzamine (60-120 mg/d) or prazosin, can be administered to patients without major cardiovascular dysfunction. There is experimental evidence of the involvement of calcium channels in nociception, and a beneficial clinical effect of nifidepine in reflex sympathetic dystrophy (RDS) has been demonstrated. Bone pain is common in tumor patients and can often be treated effectively with non-steroidal anti-inflammatory drugs. Biphosphonates (etidronate, clodronate, pamidronate derivates) also produce analgesic effects in patients with bone metastases. However, differences among the various compounds have not been clearly evaluated yet. Potent and specific radioisotopes are still under development and the use of calcitonin in bone pain is considered controversial.
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PMID:[Pharmacotherapy of cancer pain. 3. Adjuvant drugs.]. 1841 35

Intrathecal baclofen is a GABA-receptor agonist and one of the mainstay treatments of severe spasticity due to multiple sclerosis (MS). The authors report a case on the use of intrathecal baclofen administered using a Medtronic Synchromed II infusion pump. A healthy male infant (2.68 kg, Apgars 9 and 10) was born at 36 weeks gestation by cesarean section, under general anesthetic. This is the fifth reported case of intrathecal baclofen administered during pregnancy and adds to the knowledge that thus far it is relatively safe in pregnancy and may in fact be safer for the infant than oral baclofen. This is the first case report of the use of intrathecal baclofen in pregnancy and MS.
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PMID:The safety of baclofen in pregnancy: intrathecal therapy in multiple sclerosis. 1856 12

Continuous infusion of intrathecal baclofen (ITB) via a subcutaneously implanted pump has developed over the last 20 years as a powerful tool in the management of spasticity in various adult and paediatric neurological conditions. Acting more focally on spinal GABA receptors, ITB causes fewer systemic side effects than orally administered baclofen. The result is facilitation of daily caring, and symptomatic relief from painful spasm. With increasing experience of ITB use, novel applications and indications are emerging. These include the management of dystonia and chronic neuropathic pain. However, despite some recent authoritative reviews, there is still uncertainty about optimal use and evaluation of this therapy. Many challenges remain. How can efficacy of therapy best be assessed both at primary testing and after pump implantation? What is the precise mechanism of baclofen action in different brain and spinal disorders associated with spasticity and dystonia? Does placement of the spinal catheter tip influence efficacy? What is the cranio-caudal gradient of CSF baclofen levels at given pump flow rates and does this matter? What CSF baclofen levels are efficacious in various conditions? Why do some patients with the same primary condition require large differences in ITB dose? What are the relative merits of programmable versus constant infusion rate pumps? What are the implications of setting up multidisciplinary teams for long term follow up? This review evaluates these questions and highlights other areas for further investigation.
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PMID:Intrathecal baclofen therapy for neurological disorders: a sound knowledge base but many challenges remain. 1864 60

GABA signaling plays an important role in the spinal cord response to injury and subsequent motor training. Since benzodiazepines are commonly used to treat muscle spasticity in spinal cord injured subjects and the gamma2 subunit of the GABA(A) receptor is necessary for benzodiazepine binding, this subunit may be an important factor modulating sensorimotor function after an injury. Changes in gamma2 levels in muscle-specific motoneurons and surrounding astrocytes were determined approximately 3 months after a complete mid-thoracic spinal cord transection at P5 in non-trained and in step-trained spinal rats. Soleus (ankle extensor) and tibialis anterior (TA, ankle flexor) motor pools were identified using retrograde labeling via intramuscular injections of Fast Blue or Fluoro Gold, respectively. Lumbar spinal cord sections showed gamma2 immunostaining in both soleus and TA motoneurons and astrocytes. gamma2 immunoreactivity on the soma of soleus and TA motoneurons in spinal rats was differentially modulated. Compared to intact rats, spinal rats had higher levels of gamma2 in TA, and lower levels in soleus motoneurons. Step training restored GABA(A) gamma2 levels towards control values in motoneuronal pools of both muscles. In contrast, the gamma2 levels were elevated in surrounding astrocytes of both motor pools in spinal rats, and step training had no further effect. Thus, motor training had a specific effect on those neurons that were directly involved with the motor task. Since the gamma2 subunit is involved with GABA(A) receptor trafficking and synaptic clustering, it appears that this subunit could be an important component of the activity-dependent response of the spinal cord after a spinal injury.
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PMID:Changes in GABA(A) receptor subunit gamma 2 in extensor and flexor motoneurons and astrocytes after spinal cord transection and motor training. 1935 34


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