RESUMO
The Renin-Angiotensin System (RAS) is expressed in the central nervous system and has important functions that go beyond blood pressure regulation. Clinical and experimental studies have suggested that alterations in the brain RAS contribute to the development and progression of neurodegenerative diseases. However, there is limited information regarding the involvement of RAS components in Huntington's disease (HD). Herein, we used the HD murine model, (BACHD), as well as samples from patients with HD to investigate the role of both the classical and alternative axes of RAS in HD pathophysiology. BACHD mice displayed worse motor performance in different behavioral tests alongside a decrease in the levels and activity of the components of the RAS alternative axis ACE2, Ang-(1-7), and Mas receptors in the striatum, prefrontal cortex, and hippocampus. BACHD mice also displayed a significant increase in mRNA expression of the AT1 receptor, a component of the RAS classical arm, in these key brain regions. Moreover, patients with manifest HD presented higher plasma levels of Ang-(1-7). No significant changes were found in the levels of ACE, ACE2, and Ang II. Our findings provided the first evidence that an imbalance in the RAS classical and counter-regulatory arms may play a role in HD pathophysiology.
Assuntos
Angiotensina I , Enzima de Conversão de Angiotensina 2 , Doença de Huntington , Fragmentos de Peptídeos , Receptor Tipo 1 de Angiotensina , Sistema Renina-Angiotensina , Angiotensina I/genética , Angiotensina I/metabolismo , Angiotensina II/metabolismo , Enzima de Conversão de Angiotensina 2/genética , Animais , Modelos Animais de Doenças , Humanos , Doença de Huntington/genética , Camundongos , Fragmentos de Peptídeos/genética , Fragmentos de Peptídeos/metabolismo , Peptidil Dipeptidase A/metabolismo , Receptor Tipo 1 de Angiotensina/genética , Receptor Tipo 1 de Angiotensina/metabolismo , Sistema Renina-Angiotensina/genética , Sistema Renina-Angiotensina/fisiologiaRESUMO
NEW FINDINGS: What is the central question of this study? We investigated the effects of intrathecal administration of a novel toxin, CTK 01512-2, in a mouse model of Huntington's disease. We asked whether spinal cord neurons can represent a therapeutic target, given that the spinal cord seems to be involved in motor symptoms of Huntington's disease. Pharmacological approaches focusing on the spinal cord and skeletal muscles might represent a more feasible strategy than a high-risk brain intervention. What is the main finding and its importance? We provided evidence of a novel, local, neuroprotective effect of CTK 01512-2, paving a path for the development of approaches to treat motor symptoms of Huntington's disease beyond the brain. ABSTRACT: Phα1ß is a neurotoxin from the venom of the Phoneutria nigriventer spider, available as CTK 01512-2, a recombinant peptide. Owing to its antinociceptive and analgesic properties, CTK 01512-2 has been described to alleviate neuroinflammatory responses. Despite the diverse actions of CTK 01512-2 on the nervous system, little is known regarding its neuroprotective effect, especially in neurodegenerative conditions such as Huntington's disease (HD), a genetic movement disorder without cure. Here, we investigated whether CTK 01512-2 has a neuroprotective effect in a mouse model of HD. We hypothesized that spinal cord neurons might represent a therapeutic target, because the spinal cord seems to be involved in the motor symptoms of HD (BACHD) mice. We treated BACHD mice with CTK 01512-2 by intrathecal injection and performed in vivo motor behavioural and morphological analyses in the CNS (brain and spinal cord) and muscles. Our data showed that intrathecal injection of CTK 01512-2 significantly improved motor performance in the open field task. CTK 01512-2 protected neurons in the spinal cord (but not in the brain) from death, suggesting a local effect. CTK 01512-2 exerted its neuroprotective effect by inhibiting BACHD neuronal apoptosis, as revealed by a reduction in caspase-3 in the spinal cord. CTK 01512-2 was also able to revert BACHD muscle atrophy. In conclusion, our data suggest a novel role for CTK 01512-2 acting directly in the spinal cord to ameliorate morphofunctional aspects of spinal cord neurons and muscles and improve the performance of BACHD mice in motor behavioural tests. Given that HD shares similar symptoms with many neurodegenerative conditions, the findings presented herein might also be applicable to other disorders.
Assuntos
Doença de Huntington , Fármacos Neuroprotetores , Animais , Modelos Animais de Doenças , Doença de Huntington/tratamento farmacológico , Doença de Huntington/genética , Camundongos , Camundongos Transgênicos , Neurônios , Fármacos Neuroprotetores/farmacologia , Medula EspinalRESUMO
Abnormal calcium influx and glutamatergic excitotoxicity have been extensively associated with neuronal death in Huntington's disease (HD), a genetic movement disorder. Currently, there is no effective treatment for this fatal condition. The neurotoxin Phα1ß has demonstrated therapeutic effects as a calcium channel blocker, for example during pain control. However, little is known about its neuroprotective effect in HD. Herein, we investigated if Phα1ß is effective in inhibiting neuronal cell death in the BACHD mouse model for HD. We performed intrastriatal injection of Phα1ß in WT and BACHD mice. No side effects or unusual behaviors were observed upon Phα1ß administration. Using three different motor behavior tests, we observed that injection of the toxin in BACHD mice greatly improved the animals' motor-force as seen in the Wire-hang test, and also the locomotor performance, according to the Open field test. NeuN labeling for mature neuron detection revealed that Phα1ß toxin promoted neuronal preservation in the striatum and cortex, when injected locally. Intrastriatal injection of Phα1ß was not able to preserve neurons from the spinal cord and also not revert muscle atrophy in BACHD mice. Finally, we observed that Phα1ß might, at least in part, exert its protective effect by decreasing L-glutamate, measured in cerebrospinal fluid. Our data provide evidence of a novel neuroprotector effect of Phα1ß, paving a path for the development of new approaches to treat HD motor symptoms.
Assuntos
Doença de Huntington/tratamento farmacológico , Fármacos Neuroprotetores/administração & dosagem , Venenos de Aranha/administração & dosagem , Animais , Modelos Animais de Doenças , Ácido Glutâmico/metabolismo , Doença de Huntington/patologia , Camundongos , Camundongos Transgênicos , Músculo Esquelético/efeitos dos fármacos , Músculo Esquelético/patologia , Neurônios/efeitos dos fármacos , Medula Espinal/efeitos dos fármacos , Medula Espinal/patologiaRESUMO
Huntington's Disease (HD) is an autosomal dominant, progressive neurodegenerative disorder characterized by severe symptoms, including motor impairment, cognitive decline, and psychiatric alterations. Several systems, molecules, and mediators have been associated with the pathophysiology of HD. Among these, there is the Renin-Angiotensin System (RAS), a peptide hormone system that has been associated with the pathology of neuropsychiatric and neurodegenerative disorders. Important alterations in this system have been demonstrated in HD. However, the role of RAS components in HD is still unclear and needs further investigation. Nonetheless, modulation of the RAS components may represent a potential therapeutic strategy for the treatment of HD.
