title: Exogenously induced brain activation regulates neuronal activity by top-down modulation: conceptualized model for electrical brain stimulation.
abstract: Physiological and exogenous factors are able to adjust sensory processing by modulating activity at different levels of the nervous system hierarchy. Accordingly, transcranial direct current stimulation (tDCS) may use top-down mechanisms to control the access for incoming information along the neuroaxis. To test the hypothesis that brain activation induced by tCDS is able to initiate top-down modulation and that chronic stress disrupts this effect, 60-day-old male Wistar rats (n = 78) were divided into control; control + tDCS; control + sham-tDCS; stress; stress + tDCS; and stress + sham-tDCS. Chronic stress was induced using a restraint stress model for 11 weeks, and then, the treatment was applied over 8 days. BDNF levels were used to assess neuronal activity at spinal cord, brainstem, and hippocampus. Mechanical pain threshold was assessed by von Frey test immediately and 24 h after the last tDCS-intervention. tDCS was able to decrease BDNF levels in the structures involved in the descending systems (spinal cord and brainstem) only in unstressed animals. The treatment was able to reverse the stress-induced allodynia and to increase the pain threshold in unstressed animals. Furthermore, there was an inverse relation between pain sensitivity and spinal cord BDNF levels. Accordingly, we propose the addition of descending systems in the current brain electrical modulation model.
authors: Post-Graduate Program in Medical Sciences, School of Medicine, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.
authors: Lauren Naomi
authors: LN
authors: Spezia Adachi
authors: Alexandre Silva
authors: AS
authors: Quevedo
authors: Andressa
authors: A
authors: de Souza
authors: Vanessa Leal
authors: VL
authors: Scarabelot
authors: Joanna Ripoll
authors: JR
authors: Rozisky
authors: Carla
authors: C
authors: de Oliveira
authors: Paulo Ricardo
authors: PR
authors: Marques Filho
authors: Liciane Fernandes
authors: LF
authors: Medeiros
authors: Felipe
authors: F
authors: Fregni
authors: Wolnei
authors: W
authors: Caumo
authors: Iraci L S
authors: IL
authors: Torres
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001921:Brain / Q000166:cytology* / Q000502:physiology*; D019208:Brain-Derived Neurotrophic Factor / Q000378:metabolism; D004195:Disease Models, Animal; D004558:Electric Stimulation; D006930:Hyperalgesia / Q000628:therapy*; D008297:Male; D009434:Neural Pathways / Q000502:physiology; D009474:Neurons / Q000502:physiology*; D010146:Pain / Q000209:etiology; D010147:Pain Measurement; D017288:Pain Threshold; D051381:Rats; D017208:Rats, Wistar; D012149:Restraint, Physical / Q000009:adverse effects; D013116:Spinal Cord / Q000378:metabolism / Q000502:physiology*; D013315:Stress, Psychological / Q000209:etiology / Q000628:therapy*; D013997:Time Factors
chemical_list: D019208:Brain-Derived Neurotrophic Factor